Renal cell carcinoma is a malignant neoplasm arising from the renal tubular epithelium, most commonly the clear cell subtype, typically presenting in adults with hematuria, flank pain, or a palpable mass.

Exam domain	One-glance essentials
Definition / diagnosis	RCC is a malignant epithelial tumour of the kidney, distinct from urothelial carcinoma of the renal pelvis ^[1]^[2] It is the most common primary renal neoplasm, accounting for approximately 80–85% of primary renal neoplasms ^[1]^[2]
Epidemiology / risks	Major acquired risks: *smoking, obesity, hypertension, chronic kidney disease and acquired cystic kidney disease* ^[1]^[2] Dialysis-associated acquired cystic kidney disease carries a markedly increased RCC risk; hereditary syndromes include *VHL, Birt-Hogg-Dubé, hereditary papillary RCC and tuberous sclerosis* ^[1]^[2] Consider renal medullary carcinoma in a young patient with sickle-cell trait ^[1]^[2]
Core mechanism	Loss of VHL stabilises HIF-α, increasing VEGF-driven angiogenesis and explaining RCC hypervascularity ^[1]^[2] RCC characteristically extends from the renal vein into the IVC, occasionally reaching the right atrium ^[1]^[2] Clear-cell RCC is the commonest subtype; papillary and chromophobe RCC are less frequent ^[1]^[2]
Clinical picture	Most cases are incidental; haematuria, flank pain and palpable mass is a late classic triad ^[1]^[2] Examine for hypertension, anaemia/polycythaemia, non-reducing left varicocele and bilateral leg oedema ^[1]^[2] Paraneoplastic clues: hypercalcaemia, polycythaemia, renin-mediated hypertension and *Stauffer syndrome* ^[1]^[2] Common metastases: lung, bone, liver and brain; bone lesions are typically lytic and vascular ^[1]^[2]
Investigations	Contrast CT renal protocol characterises and stages the mass; enhancement > 10–15 HU supports a solid tumour ^[1]^[2] MRI is preferred when IVC tumour thrombus is suspected, to define its cranial extent for operative planning ^[1]^[2] Check urinalysis, CBC, calcium, LFTs, renal function and prognostic blood indices; there is no serum tumour marker ^[1]^[2] Do not routinely biopsy a characteristic resectable RCC; biopsy when lymphoma, metastasis, benign disease or ablation is suspected ^[1]^[2]
Management	Localised RCC is treated surgically: partial nephrectomy for T1 up to 7 cm when feasible; radical nephrectomy generally for larger or locally advanced tumours ^[1]^[2] Partial nephrectomy is especially important for a solitary kidney, bilateral/multifocal tumours or impaired renal reserve ^[1]^[2] Control the vascular pedicle early; IVC thrombus above the hepatic veins may require cardiopulmonary bypass ^[1]^[2] Metastatic disease requires specialist systemic therapy; conventional chemotherapy has no role ^[1]^[2]
Complications	Venous extension can cause non-reducing left varicocele, bilateral oedema, ascites, Budd–Chiari-like congestion or tumour pulmonary embolism ^[1]^[2] Paraneoplastic complications include hypercalcaemia, erythrocytosis, hypertension and hepatic dysfunction from *Stauffer syndrome* ^[1]^[2] Metastases may cause respiratory compromise, pathological fracture, spinal cord compression, seizures or raised intracranial pressure ^[1]^[2] Surgery risks bleeding, urine leak after partial nephrectomy, adjacent-organ injury and renal failure after radical nephrectomy ^[1]^[2]
Prevention / follow-up	Stop smoking and address obesity and hypertension to reduce modifiable RCC risk ^[1]^[2] Patients on long-term dialysis with acquired cystic kidney disease require *yearly ultrasound surveillance* ^[1]^[2] Preserve nephron mass where oncologically safe and monitor renal function lifelong after nephrectomy ^[1]^[2]
Exam traps	A central renal-pelvis filling defect suggests urothelial carcinoma, requiring nephroureterectomy rather than nephrectomy alone ^[1]^[2] Macroscopic fat strongly suggests angiomyolipoma; a central stellate scar does not reliably exclude RCC ^[1]^[2] Bilateral homogeneous renal masses with lymphadenopathy suggest lymphoma; obtain tissue before systemic treatment ^[1]^[2] Deranged LFTs without liver metastases may be *Stauffer syndrome* and can reverse after tumour resection ^[1]^[2]

References

^[1] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (pp. 7, 17) ^[2] Senior notes: felixlai.md (Renal cell carcinoma section)

Renal Cell Carcinoma (RCC) — Definition, Epidemiology, Risk Factors, Anatomy, Etiology, Pathophysiology, Classification & Clinical Features

Renal cell carcinoma (RCC) is a malignant neoplasm arising from the renal tubular epithelium (i.e., the renal cortex/parenchyma). Let's break down the name:

Renal = kidney (Latin: ren)
Cell = referring to the epithelial cells lining the renal tubules
Carcinoma = malignant tumour of epithelial origin (Greek: karkinos = crab, -oma = tumour)

So "renal cell carcinoma" literally tells you: a cancer of the epithelial cells of the kidney. This distinguishes it from urothelial carcinoma of the renal pelvis (which arises from transitional epithelium), nephroblastoma (embryonic tissue), and renal sarcomas (mesenchymal origin).

RCC is the most common primary renal neoplasm, accounting for 80–85% of all primary renal neoplasms ^[1]^[2]^[3].

It is notoriously called the "internist's tumour" because of its protean manifestations — it can present with almost anything due to paraneoplastic syndromes, and is also called the "great mimic."

2. Epidemiology

RCC accounts for approximately 2–4% of all adult cancers, with ~214,000 new cases per year worldwide ^[3].
In Hong Kong: incidence ~4.8/100,000; mortality ~1.6/100,000 ^[3].
Incidence has been rising globally, partly due to increased use of cross-sectional imaging (CT/USG) detecting incidental small renal masses — the so-called "incidentaloma" effect.

Factor	Detail
Sex	Male predominance (M:F ≈ 1.5–2:1) ^[2]^[3] — androgens may promote tumour growth, and males have higher rates of smoking and occupational exposures
Age	6th–8th decade of life (median age of diagnosis = 64 years) ^[2]^[3]
Ethnicity	Less common in Asians compared to Western populations ^[3]; higher in African Americans in the US

Type	Proportion	Origin
Renal cell carcinoma	80–85%	Renal cortex (tubular epithelium)
Urothelial (transitional cell) carcinoma	~8%	Renal pelvis
Nephroblastoma (Wilms' tumour)	5–6%	Embryonic nephrogenic tissue (children)
Others	Rare	Oncocytoma, sarcomas, etc.

High Yield — Incidental Detection

50–60% of RCC cases are now discovered incidentally on imaging (e.g., abdominal USG or CT done for other reasons) ^[4]. This means the majority of patients are asymptomatic at presentation. The classic triad of haematuria, flank pain, and palpable mass is seen in only 10–20% — and when present, usually indicates advanced disease.

3. Relevant Anatomy and Function

Understanding the anatomy is critical because it explains patterns of spread and clinical features.

The kidney has two functional zones:
- Cortex (outer) — contains glomeruli and proximal/distal convoluted tubules → this is where RCC arises
- Medulla (inner) — contains loops of Henle and collecting ducts
The renal pelvis (funnel-shaped structure collecting urine) is lined by urothelium — this is where urothelial carcinoma arises (distinct from RCC)

This is where things get interesting and clinically important:

Renal arteries → branch from the aorta at L1–L2 level
Renal veins → drain directly into the IVC
- The left renal vein is longer, crosses anterior to the aorta, and receives the left gonadal (testicular/ovarian) vein and the left adrenal vein
- The right renal vein is shorter, draining directly into the IVC; the right gonadal vein drains directly into the IVC (not via the renal vein)

Why does this matter?

RCC has a unique propensity to invade the renal vein and extend as a tumour thrombus into the IVC, and even into the right atrium. This is almost pathognomonic for RCC among solid organ cancers.

Left-sided RCC invading the left renal vein → obstructs drainage of the left gonadal vein → left-sided varicocele (this is a classic exam pearl!) ^[4]
IVC invasion → bilateral lower limb oedema, ascites, hepatomegaly (Budd-Chiari-like picture), and even pulmonary embolism if tumour thrombus dislodges ^[4]

Para-aortic and paracaval lymph nodes (retroperitoneal lymph nodes)
Most common site of regional metastasis: retroperitoneal lymph nodes ^[2]

RCC metastasises via:

Haematogenous spread (most important — via the renal vein → IVC → systemic circulation)
Lymphatic spread (retroperitoneal nodes)
Direct invasion (perinephric fat, adrenal gland, adjacent structures)

Most common sites of distant metastasis: lung (most common, ~50–60%), bone, liver, brain, lymph nodes ^[2]^[4]

Why does RCC love to metastasise to the lung?

Because the venous drainage of the kidney goes directly into the IVC → right heart → pulmonary arteries → lungs. This is the first capillary bed that tumour emboli encounter. This is exactly the same reason liver cancers also commonly metastasise to the lungs (hepatic veins → IVC → lungs). The lung is the "first filter" for venous drainage from the kidney.

The kidney is enclosed within Gerota's fascia (perirenal fascia), which forms a natural anatomical barrier.
Tumour confined within Gerota's fascia has a better prognosis (T1–T3a) than tumour breaching it (T4).
This is why radical nephrectomy removes the kidney along with Gerota's fascia, the perirenal fat, and ipsilateral adrenal (if involved).

4. Etiology and Risk Factors

RCC is a multifactorial disease. Risk factors can be organised by the surgical sieve or, more practically for clinical clerking, by history-taking categories:

4.2 Modifiable Risk Factors

Smoking is a major risk factor: RR ≈ 1.31 (all smokers), 1.36 (current smokers), 1.16 (ex-smokers) ^[1]^[3]
Also associated with more advanced disease at presentation ^[3]
Mechanism: Tobacco smoke contains nitrosamines and polycyclic aromatic hydrocarbons that are filtered by the kidney, causing direct mutagenic damage to tubular epithelial cells. Smoking also causes chronic tissue hypoxia, which upregulates hypoxia-inducible factor (HIF) — the same pathway involved in VHL-related RCC (see pathophysiology below).

Obesity is an independent risk factor ^[1]^[2]
Mechanism: Multiple pathways:
- Increased circulating insulin and IGF-1 (mitogenic)
- Chronic inflammation (adipokines, IL-6, TNF-α)
- Altered sex hormone metabolism (higher oestrogen levels)
- Lipid peroxidation causing oxidative DNA damage in renal tubular cells

Hypertension is a risk factor ^[1]^[2]
Mechanism: Unclear, but hypotheses include:
- Chronic renal hypoxia from arteriolar damage → HIF upregulation
- Increased ROS (reactive oxygen species) damaging tubular DNA
- Note: antihypertensive medications (especially diuretics) were once implicated, but HTN itself appears to be the independent risk factor

Cadmium, asbestos, petroleum by-products ^[2]^[3]
Nitrosamines, aflatoxin B1 ^[2]
Occupations: leather tanners, shoe workers ^[2]
Mechanism: These are direct or indirect carcinogens that accumulate in the renal cortex during filtration and excretion.

Heavy and prolonged use of aspirin, paracetamol (acetaminophen), and NSAIDs ^[2]^[3]
Mechanism: Chronic analgesic use → analgesic nephropathy → chronic tubular injury and regenerative proliferation → increased mutation risk. Similar mechanism to why chronic inflammation predisposes to cancer elsewhere.

4.3 Medical Risk Factors

Acquired polycystic kidney disease (due to chronic dialysis): 30× risk of RCC ^[1]^[2]^[3]
Require yearly USG screening ^[3]
Key distinction: These kidneys are small to normal in size (unlike ADPKD where kidneys are enlarged) ^[2]
Mechanism: Chronic uraemia → cyst formation → epithelial dysplasia within cysts → malignant transformation. The cystic environment promotes genomic instability.

Acquired Cystic Kidney Disease vs. ADPKD

Students often confuse these. Acquired cystic kidney disease occurs in patients on long-term dialysis (haemo- or peritoneal), and kidneys are small to normal in size. ADPKD is a genetic condition with large kidneys. Both can develop RCC, but the dialysis-associated risk is much more dramatic (30× increase).

Associated immunosuppression increases RCC risk ^[2]
Mechanism: Immunosuppressive drugs (e.g., CNIs, mycophenolate) reduce immune surveillance against nascent tumour cells. This is a general principle: immunosuppression → reduced immune editing → cancer.

Mechanism likely relates to chronic inflammation and possibly direct viral effects on renal epithelium.

D. Sickle Cell Disease — specifically associated with renal medullary carcinoma (a very aggressive subtype) [3][5]

Chronic inflammation and irritation of renal epithelium.

Direct DNA damage from radiation and alkylating agents.

Genetic predisposition: Family history and inherited syndromes such as von Hippel-Lindau, Birt-Hogg-Dubé, hereditary papillary RCC, and tuberous sclerosis ^[1].

Hereditary RCC accounts for ~5% of cases but is disproportionately important because:

These patients present younger (often < 40 years)
Tumours are often bilateral and multifocal
Understanding the genetics teaches us the molecular pathogenesis of sporadic RCC too

Syndrome	Gene	Chromosome	Inheritance	Associated RCC Subtype	Other Associations
Von Hippel-Lindau (VHL)	VHL	3p25	AD	Clear cell RCC (~40%)	Phaeochromocytoma (14%), cerebellar haemangioblastoma, retinal angiomas, renal cysts (75%), pancreatic cysts/NETs, epididymal cystadenoma ^[2]^[3]
Hereditary papillary RCC (HPRCC)	MET	7q31	AD	Bilateral, multifocal papillary RCC ^[3]	—
Birt-Hogg-Dubé	FLCN (folliculin)	17p11	AD	Chromophobe RCC, oncocytoma, hybrid tumours	Fibrofolliculomas (skin), pulmonary cysts, spontaneous pneumothorax
Tuberous sclerosis complex (TSC)	TSC1/TSC2	9q34/16p13	AD	RCC develops in < 5% of individuals ^[3]	Angiomyolipomas (most common renal lesion in TSC), cortical tubers, cardiac rhabdomyomas, LAM
Hereditary leiomyomatosis and RCC (HLRCC)	FH (fumarate hydratase)	1q42	AD	Aggressive papillary type 2 RCC	Cutaneous and uterine leiomyomas

5. Pathophysiology

This is the most important pathway to understand because:

VHL gene mutation is found in ~90% of sporadic clear cell RCC (not just hereditary cases) ^[3]
It explains the biology of the tumour and the rationale for targeted therapy

Normal VHL function:

Under normal oxygen conditions (normoxia):

HIF-α (hypoxia-inducible factor alpha) is hydroxylated by prolyl hydroxylases (oxygen-dependent enzymes)
Hydroxylated HIF-α is recognised by the VHL protein (pVHL)
pVHL is part of an E3 ubiquitin ligase complex → tags HIF-α for proteasomal degradation
Result: HIF-α is kept at low levels → downstream targets are NOT activated

What happens when VHL is lost (mutated/deleted)?

Key downstream effects of HIF-α accumulation:

Target Gene	Protein	Effect	Clinical Relevance
VEGF	Vascular endothelial growth factor	Angiogenesis — new blood vessel formation	Highly vascular tumour on imaging; target of anti-VEGF therapy (sunitinib, pazopanib, bevacizumab)
PDGF	Platelet-derived growth factor	Stromal support, vessel maturation	Target of multi-kinase inhibitors
EPO	Erythropoietin	Red cell production	Paraneoplastic polycythaemia
TGF-α	Transforming growth factor alpha	Autocrine growth stimulation via EGFR	Tumour proliferation
GLUT1	Glucose transporter 1	Increased glucose uptake	Warburg effect, FDG-PET avidity
CA-IX	Carbonic anhydrase IX	pH regulation	Immunohistochemistry marker for clear cell RCC

Why "clear cell"?

The clear cytoplasm seen on histology is due to accumulation of lipid and glycogen in the cytoplasm. During histological processing (fixation and staining with H&E), these lipids and glycogen are dissolved out, leaving empty-appearing ("clear") cells. The lipid/glycogen accumulation is driven by HIF-mediated metabolic reprogramming (increased glucose uptake via GLUT1 and altered lipid metabolism).

VHL — The Master Switch

Think of VHL as the "brake pedal" on angiogenesis and cell growth. When VHL is lost, the car (tumour) accelerates uncontrollably. This is why clear cell RCC is one of the most vascular solid tumours — it's essentially pumping out VEGF all the time. This also explains why it responds to anti-angiogenic therapies (TKIs targeting VEGF receptor) and why it's classically resistant to conventional chemotherapy (chemotherapy relies on good blood supply to deliver drugs, but paradoxically, the disordered vasculature in RCC is leaky and dysfunctional).

RCC Subtype	Key Genetic Alteration	Pathway
Clear cell	Del(3p), VHL mutation ^[3]	HIF/VEGF pathway (as above)
Papillary Type 1	Trisomy 7, MET gene activation (7q) ^[3]	MET/HGF signalling → cell proliferation and motility
Papillary Type 2	Trisomy 16, 17; loss of Y ^[3]; FH mutations in HLRCC	Fumarate accumulation → HIF stabilisation (pseudohypoxia)
Chromophobe	Multiple chromosomal losses (1, 2, 6, 10, 13, 17, 21)	mTOR pathway activation

RCC is notorious for paraneoplastic phenomena (~6–10% of patients) ^[4]. The mechanisms are:

Paraneoplastic Phenomenon	Mechanism	Frequency
Polycythaemia	Tumour produces EPO (remember: HIF-α drives EPO transcription when VHL is lost)	~3–5%
Hypercalcaemia	Tumour produces PTHrP (parathyroid hormone-related peptide) mimicking PTH; also 1α-hydroxylation of vitamin D by tumour cells	~13–20%
Hypertension (non-renal artery related)	Tumour produces renin → RAAS activation	Uncommon
Anaemia of chronic disease	Chronic inflammation (IL-6, hepcidin upregulation) → functional iron deficiency	Common
Stauffer syndrome (non-metastatic hepatic dysfunction)	Unknown mechanism — likely cytokine-mediated (IL-6); characterised by abnormal LFTs, hepatosplenomegaly, fever without liver metastases; resolves after nephrectomy	~3–6%
Fever/cachexia	Cytokine production (IL-6, TNF-α)	Common

Stauffer Syndrome

This is a frequently tested concept. Stauffer syndrome = non-metastatic liver dysfunction in RCC ^[4]. The LFTs are abnormal (raised ALP, GGT, bilirubin), there is hepatosplenomegaly, but there are no liver metastases on imaging. It is a paraneoplastic phenomenon that reverses after tumour resection. If LFT abnormalities persist post-nephrectomy, think recurrence. Do not mistake it for metastatic disease and deny the patient potentially curative surgery!

6. Classification

The main subtypes and their features ^[1]^[5]:

Subtype	Approximate Incidence	Origin/Histology	Key Features
Clear Cell RCC (ccRCC)	~70–80%	Proximal tubule epithelial cells	Most common subtype; characterised by clear cytoplasm due to lipid/glycogen; associated with VHL gene mutation; aggressive behaviour ^[5]
Papillary RCC (pRCC)	~10–15%	Distal tubule epithelial cells	Divided into Type 1 (small basophilic cells, MET gene alterations, better prognosis) and Type 2 (larger eosinophilic cells, worse prognosis); new WHO classifications are evolving ^[5]
Chromophobe RCC	~5–10%	Distal tubule intercalated cells	Pale eosinophilic cytoplasm with distinct cell membranes; better prognosis than ccRCC ^[5]
Collecting Duct Carcinoma	~1%	Collecting ducts	Rare, aggressive subtype with poor prognosis ^[5]
Renal Medullary Carcinoma	< 1%	Medullary region; related to sickle cell disease	Very aggressive, mostly in young patients with sickle cell trait ^[5]
Translocation RCC	Rare	Variable; involving TFE3 or TFEB gene translocations	Usually affects children and young adults; distinct molecular pathology ^[5]
Mucinous Tubular and Spindle Cell Carcinoma	Rare	Distal tubule	Indolent behaviour; low metastatic potential ^[5]

Stage	T	Description
T1a		Tumour ≤ 4 cm, limited to kidney
T1b		Tumour > 4 cm but ≤ 7 cm, limited to kidney
T2a		Tumour > 7 cm but ≤ 10 cm, limited to kidney
T2b		Tumour > 10 cm, limited to kidney
T3a		Tumour extends into renal vein or its segmental branches, or invades perirenal/renal sinus fat, but not beyond Gerota's fascia
T3b		Tumour extends into IVC below diaphragm
T3c		Tumour extends into IVC above diaphragm or invades wall of IVC
T4		Tumour invades beyond Gerota's fascia (including contiguous extension into ipsilateral adrenal gland)

Stage	N	Description
N0		No regional lymph node metastasis
N1		Metastasis in regional lymph node(s)

Stage	M	Description
M0		No distant metastasis
M1		Distant metastasis

Prognostic Stage Grouping:

Stage	TNM
I	T1 N0 M0
II	T2 N0 M0
III	T1–T2 N1 M0 or T3 N0–N1 M0
IV	T4 any N M0 or any T any N M1

Key Staging Points for Exams

T1: ≤ 7 cm, confined to kidney (a ≤ 4 cm, b 4–7 cm) — these are candidates for partial nephrectomy
T3: renal vein / IVC involvement or perinephric fat invasion (but still within Gerota's) — this is the "tumour thrombus" stage
T4: beyond Gerota's fascia — locally advanced
Any M1 = Stage IV regardless of T or N

The grading system has transitioned from the older Fuhrman system to the WHO/ISUP grading system (2013, updated), based on nucleolar prominence:

Grade	Description	Prognosis
1	Nucleoli absent or inconspicuous at 400×	Best
2	Nucleoli conspicuous at 400× but inconspicuous at 100×
3	Nucleoli conspicuous at 100×
4	Extreme nuclear pleomorphism, sarcomatoid/rhabdoid differentiation	Worst

7. Clinical Features

RCC is usually asymptomatic and presents until disease is advanced ^[2]. The presentation can be categorised as:

Incidental (most common today)
Local symptoms (haematuria, flank pain, mass)
Symptoms from venous invasion
Metastatic symptoms
Paraneoplastic syndromes

7.2 Symptoms

This is the most common presentation in the modern era
Found on USG/CT performed for other indications (e.g., abdominal pain workup, health screening)
Why? Widespread availability of cross-sectional imaging. These tumours are often small and asymptomatic.

The classic triad is: haematuria + flank pain + palpable renal mass

However, this triad is now rare and when present, usually indicates advanced disease.

Symptom	Mechanism
Haematuria (most common symptom when symptomatic, ~40–60%)	Tumour invades into the collecting system (renal pelvis/calyces), eroding blood vessels → blood enters the urine. Typically painless and intermittent (macro or micro). May cause clot colic if large clots pass through the ureter.
Flank pain (~40%)	Due to capsular distension (the renal capsule is innervated by T10–L1 sensory fibres; as tumour grows, it stretches the capsule causing a dull, constant ache). Can also be caused by haemorrhage within the tumour, ureteric obstruction by clots, or direct nerve invasion.
Palpable abdominal/flank mass (~25%)	The tumour must be large enough to be palpable — usually > 10 cm. The mass is in the loin, moves with respiration (attached to diaphragm via kidney), is ballottable (bimanually palpable because the kidney is a retroperitoneal organ).

RCC uniquely invades into the renal vein, IVC, and even the right atrium ^[4].

Symptom	Mechanism
Left-sided varicocele	Left renal vein invasion → obstructs the left gonadal (testicular) vein which drains into the left renal vein → venous congestion → dilatation of the pampiniform plexus = varicocele ^[4]. This is classically non-reducible on lying down (unlike idiopathic varicoceles). A new left varicocele in an older man that does NOT decompress when supine should raise alarm for RCC.
Bilateral lower limb oedema	IVC invasion/obstruction → impaired venous return from lower limbs → bilateral (symmetric) pitting oedema ^[4]. Note: unilateral oedema is more suggestive of DVT; bilateral suggests proximal obstruction (IVC).
Ascites	IVC obstruction → increased hydrostatic pressure in hepatic veins → transudative ascites (similar mechanism to Budd-Chiari syndrome) ^[4]
Pulmonary embolism	Tumour thrombus in the IVC can fragment and embolise to the pulmonary arteries ^[4]. This can be the presenting event.
Dilated abdominal wall veins (caput medusae-like)	IVC obstruction → blood seeks collateral pathways → superficial abdominal/thoracic veins become dilated

Left Varicocele — A Classic Exam Trap

A new-onset left varicocele in a man > 40 years that does not decompress on lying flat should prompt investigation for a left renal mass. The reason it's always the LEFT side: the left testicular vein drains into the left renal vein (the right testicular vein drains directly into the IVC, so right-sided RCC less commonly causes varicocele). If you see a right-sided varicocele, think of IVC obstruction or situs inversus.

25% of patients present with advanced locoregional disease or distant metastasis ^[2].

Site	Symptoms	Mechanism
Lung (most common, ~50–60%)	Cough, haemoptysis, dyspnoea, chest pain	Haematogenous spread via renal vein → IVC → right heart → pulmonary arteries. Can present as solitary or multiple pulmonary nodules, or lymphangitis carcinomatosa
Bone (~30%)	Bone pain, pathological fractures, spinal cord compression	Haematogenous spread. RCC bony metastases are characteristically lytic (osteoclast-activating) and highly vascular — important because biopsy of bone mets can cause significant haemorrhage. Common sites: spine, pelvis, femur, humerus
Brain (~5–10%)	Headache, seizures, focal neurological deficits	Haematogenous spread
Liver	RUQ pain, jaundice (late), hepatomegaly	Haematogenous or direct extension (right kidney adjacent to liver)
Retroperitoneal lymph nodes	Usually asymptomatic; may cause back pain or ureteric obstruction	Lymphatic drainage

"Cannonball" lung metastases — RCC is one of the classic causes of multiple, well-defined, round pulmonary nodules on CXR (the others include choriocarcinoma, melanoma, and sarcoma). These are called "cannonball" metastases.

Symptom	Mechanism
Weight loss, anorexia, malaise	Cancer cachexia — tumour produces cytokines (TNF-α, IL-6) that increase basal metabolic rate, suppress appetite, and promote muscle catabolism
Fever of unknown origin (FUO)	Tumour produces pyrogens (IL-1, IL-6, TNF-α). RCC is one of the classic causes of FUO of neoplastic origin
Night sweats	Same cytokine-mediated mechanism

7.3 Signs

Sign	Significance
Cachexia	Advanced disease
Pallor	Anaemia (chronic disease or haematuria-related)
Plethora (ruddy complexion)	Polycythaemia from EPO production (paraneoplastic)
Hypertension	Paraneoplastic (renin production) or renal artery compression

Sign	Significance
Palpable flank/loin mass	Large tumour; ballottable; moves with respiration
Hepatomegaly	Liver metastases or Stauffer syndrome (non-metastatic hepatic dysfunction)
Ascites	IVC obstruction or peritoneal metastases

Sign	Significance
Left varicocele (non-reducing on lying flat)	Left renal vein invasion ^[4]

Sign	Significance
Bilateral non-pitting → pitting oedema	IVC obstruction

E. Paraneoplastic Signs (see table in Section 5.3)

Only 20% of renal masses are benign ^[4]. Key benign mimics:

Lesion	Features	Key Distinguishing Point
Oncocytoma	Well-circumscribed, central stellate scar on CT; composed of oncocytes (eosinophilic cells)	Cannot reliably distinguish from chromophobe RCC on imaging alone; often requires histology
Angiomyolipoma (AML)	Contains fat, smooth muscle, and blood vessels; strongly associated with tuberous sclerosis	Macroscopic fat on CT (Hounsfield units < -20) is virtually diagnostic; risk of haemorrhage if > 4 cm
Simple renal cyst	Bosniak I or II (thin wall, no enhancement, no septation)	Very common, benign, no follow-up needed
Complex renal cyst	Bosniak IIF–IV → increasing likelihood of malignancy	Bosniak IV ≈ 100% malignancy rate → requires surgical excision

High Yield Summary

RCC arises from renal tubular epithelium (most commonly proximal tubule → clear cell type, 70–80%).
Epidemiology: Male > Female, 6th–8th decade, median age 64. In HK: incidence 4.8/100,000.
Major risk factors: Smoking, obesity, hypertension, acquired cystic kidney disease (30× risk in dialysis patients), VHL syndrome, Birt-Hogg-Dubé, hereditary papillary RCC, tuberous sclerosis.
VHL pathway is central: Loss of VHL → HIF-α accumulation → VEGF (angiogenesis), EPO (polycythaemia), PDGF (proliferation). This explains the tumour's hypervascularity, anti-VEGF therapy responsiveness, and chemo-resistance.
Most patients are asymptomatic — 50–60% found incidentally on imaging.
Classic triad (haematuria + flank pain + palpable mass) = late presentation (10–20%).
RCC uniquely invades the renal vein and IVC → left varicocele (non-reducing), bilateral LL oedema, PE, ascites.
Paraneoplastic syndromes (6–10%): polycythaemia (EPO), hypercalcaemia (PTHrP), HTN (renin), Stauffer syndrome (non-metastatic hepatic dysfunction → reversible post-nephrectomy), anaemia of chronic disease.
Most common metastatic sites: Lung (cannonball mets) > bone (lytic, vascular) > liver > brain > lymph nodes.
Histological subtypes: Clear cell (70–80%) > papillary (10–15%) > chromophobe (5–10%) > collecting duct (~1%) > medullary (< 1%, sickle cell trait).

Active Recall - Renal Cell Carcinoma (Part 1)

^[1] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (pp. 7, 17) ^[2] Senior notes: felixlai.md (Renal cell carcinoma section) ^[3] Senior notes: Ryan Ho Urogenital.pdf (p. 145, Section 7.3) ^[4] Senior notes: maxim.md (Renal cell carcinoma section) ^[5] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (p. 17 — RCC Subtypes table)

Differential Diagnosis of a Renal Mass

When you encounter a renal mass — whether discovered incidentally on imaging, found during a haematuria workup, or detected because the patient has flank pain — you must think systematically. Not every renal mass is RCC. The differential is broad, and getting it wrong has major consequences: you don't want to do a radical nephrectomy for a lymphoma (which is treated with chemotherapy) or panic about a simple cyst.

The approach is to ask three sequential questions:

Is this mass real? (Artefact, normal variant, pseudotumour such as a prominent column of Bertin)
Is it cystic or solid? (Simple cysts are overwhelmingly benign; solid masses are malignant until proven otherwise)
If solid or complex cystic — is it benign or malignant?

Differential Diagnoses of Renal Masses — Detailed Breakdown

Only ~20% of renal masses are benign ^[4]. Key benign differentials:

Diagnosis	Key Features	Why It Mimics RCC	How to Distinguish
Simple renal cyst	Asymptomatic, ovoid anechoic mass with smooth wall on USG ^[3]	Very common; large cysts may cause flank mass or pain	Bosniak I–II criteria: thin wall, no septations, no enhancement, no calcification. Requires no follow-up
Angiomyolipoma (AML)	Fat attenuation, enhancing without calcification on CT; associated with tuberous sclerosis complex ^[3]	Can be large, cause pain, and even rupture/haemorrhage (especially if > 4 cm)	Macroscopic fat on CT (Hounsfield units < −20 HU) is virtually diagnostic. Contains fat + smooth muscle + blood vessels ("angio-myo-lipoma" = vessels-muscle-fat). Risk of spontaneous haemorrhage (Wunderlich syndrome) if > 4 cm → embolisation or surgery
Oncocytoma	Homogeneous, well-circumscribed solid mass ^[3]; characteristically has a central stellate scar on CT	Solid, enhancing mass that looks identical to chromophobe RCC on imaging	Cannot reliably distinguish from chromophobe RCC on imaging alone — often requires histological confirmation. Composed of oncocytes (eosinophilic, mitochondria-rich cells). Benign — no metastatic potential
Infectious mass (renal abscess, focal pyelonephritis, xanthogranulomatous pyelonephritis)	Often associated with signs/symptoms of UTI and systemic upset ^[3]	Can appear as an enhancing renal mass with irregular walls	Clinical context: fever, leucocytosis, pyuria, raised CRP/procalcitonin. XGP classically mimics RCC and is only diagnosed post-nephrectomy
Renal pseudotumour (hypertrophied column of Bertin, dromedary hump, foetal lobulation)	Normal anatomical variant of renal parenchyma	Can appear as a "mass" on USG	Enhances identically to surrounding normal cortex on CT; no distortion of architecture
Complex renal cyst	Cystic lesion with septations, calcifications, or wall thickening	Bosniak III–IV cysts have significant malignancy risk (Bosniak IV ≈ 100%)	Bosniak classification determines management (see below)

Bosniak Classification of Renal Cysts — Quick Reference

Category	Features	Malignancy Risk	Management
I	Simple: thin wall, no septa, no calcification, no enhancement	~0%	No follow-up
II	Few thin septa, fine calcification, hyperdense cysts (< 3 cm), no enhancement	~0%	No follow-up
IIF ("F" = follow-up)	More septa, minimally thickened; minimal enhancement; ≥ 3 cm hyperdense cysts	~5%	Serial imaging
III	Thickened irregular walls/septa, measurable enhancement	~50%	Surgery or biopsy
IV	Clearly enhancing soft tissue component	~100%	Surgery (treat as RCC)

Xanthogranulomatous Pyelonephritis — The Great Mimicker

XGP is a chronic destructive granulomatous infection (usually from Proteus mirabilis or E. coli with staghorn calculus) that destroys and replaces the renal parenchyma with lipid-laden macrophages. On CT it can look exactly like a locally advanced RCC (irregular mass, perinephric extension). It is often only diagnosed after nephrectomy when the pathologist finds granulomatous tissue instead of carcinoma. Clinical clue: usually occurs in middle-aged women with a history of recurrent UTIs and a non-functioning kidney on the affected side.

Diagnosis	Key Features	Why It Matters	How to Distinguish from RCC
Urothelial carcinoma of the renal pelvis	Arises from transitional epithelium lining the renal pelvis (~8% of renal malignancies) ^[2]^[3]	Treated differently: nephroureterectomy (not radical nephrectomy alone), because the entire urothelial tract is at risk (field change)	Typically presents as a central filling defect in the renal pelvis on CT urogram (not a cortical mass). Often associated with hydronephrosis. Urine cytology may be positive. Risk factors: smoking, aristolochic acid (Chinese herbal nephropathy — important in Hong Kong), analgesic nephropathy
Renal metastasis	Usually multiple lesions with borderline enhancement + widespread metastatic disease ^[3]	Treatment is systemic (chemotherapy/immunotherapy), not surgical — so tissue diagnosis is critical	Common primaries that metastasise to kidney: lung, breast, GIT, prostate, melanoma ^[2]. Imaging: usually multiple, bilateral, small, minimally enhancing lesions in a patient with known primary cancer. Consider obtaining tissue biopsy if may affect management ^[3]
Lymphoma	Primary renal lymphoma is rare; secondary involvement more common (50% of lymphoma at autopsy have renal involvement)	Treatment is chemotherapy, NOT surgery — this is the critical distinction. Doing a nephrectomy for lymphoma is a disaster	Imaging: multiple bilateral homogeneous masses, or diffuse infiltration causing renomegaly without distortion of the collecting system. Consider obtaining tissue biopsy if may affect management ^[3]. Look for other evidence of lymphoma (lymphadenopathy, splenomegaly, B symptoms)
Wilms' tumour (nephroblastoma)	Most common primary renal malignancy in children (< 15 years; peak age 3) ^[6]	Presents as an asymptomatic abdominal mass in a child; different staging and treatment protocol from RCC	Age is the key: if a child has a renal mass, think Wilms' first. If an adult has a renal mass, think RCC first. Wilms' rarely crosses the midline (cf. neuroblastoma which does). Associated with WAGR syndrome, Beckwith-Wiedemann syndrome, Denys-Drash syndrome ^[6]
Renal sarcoma	Rare (< 1%); includes leiomyosarcoma, liposarcoma, angiosarcoma	Highly aggressive with poor prognosis	Usually large, heterogeneous mass; tissue diagnosis needed
Collecting duct carcinoma	Arises from collecting ducts; rare, aggressive subtype with poor prognosis ^[5]	Behaves more like urothelial carcinoma than typical RCC; poor response to anti-VEGF therapy	Central (medullary) location rather than cortical; infiltrative pattern on CT
Renal medullary carcinoma	Very aggressive, mostly in young patients with sickle cell trait ^[5]	Nearly universally fatal; presents with metastatic disease	Young patient with sickle cell trait/disease + aggressive renal mass = pathognomonic

Condition	Key Features	How to Distinguish
Renal abscess/perinephric abscess	Fever, leucocytosis, pyuria; history of UTI or haematogenous seeding	CT shows rim-enhancing fluid collection ± gas; responds to antibiotics/drainage
Renal infarct	Wedge-shaped non-enhancing area; clinical context of AF, endocarditis, aortic disease	Peripheral, wedge-shaped, does not enhance; cortical rim sign (thin rim of viable subcapsular cortex)
Polycystic kidney disease (ADPKD)	Bilateral enlarged kidneys with multiple cysts	Family history, bilateral, large kidneys — but note: RCC can occur within ADPKD kidneys too
Haematoma (subcapsular or perirenal)	History of trauma, anticoagulation, or tumour bleed	CT shows high-density non-enhancing collection; may need follow-up to exclude underlying tumour
Renal tuberculosis	Chronic destructive granulomatous infection	"Putty kidney" (calcified non-functioning kidney); sterile pyuria; AFB on EMU; history of TB exposure

Let's think about why we care about the differential:

RCC: Treatment is primarily surgical (partial or radical nephrectomy). Anti-VEGF targeted therapy or immunotherapy for metastatic disease. Chemotherapy and radiotherapy are largely ineffective.
Urothelial carcinoma of the renal pelvis: Requires nephroureterectomy (removing kidney + entire ureter + bladder cuff) because the entire urothelium is at risk from field cancerisation.
Lymphoma / metastasis to kidney: Treatment is systemic (chemotherapy/immunotherapy). Surgery would be inappropriate and harmful. This is why biopsy is indicated when lymphoma or metastasis is suspected ^[3] — in contrast to typical RCC where biopsy is generally avoided.
Angiomyolipoma: Benign. If small and asymptomatic, observation only. If > 4 cm or symptomatic, selective arterial embolisation or nephron-sparing surgery.
Oncocytoma: Benign. But since it cannot be reliably distinguished from chromophobe RCC on imaging, it often ends up being resected (and the diagnosis is made post-operatively by the pathologist).

When to Biopsy a Renal Mass

CT-guided core biopsy is traditionally NOT done for suspected RCC due to risk of tumour seeding ^[3]. Instead, diagnosis is made from the nephrectomy specimen itself (surgery serves as both diagnosis and treatment).

Indications for renal mass biopsy ^[3]:

Renal mass of unknown origin (suspicious for metastasis, lymphoma, or non-malignant cause)
Metastatic disease where the primary is uncertain and systemic therapy is planned
Patient preference / unfit for surgery — to guide systemic therapy
Before thermal ablation of a small renal mass

The key principle: you biopsy when the result would change management (e.g., if it's lymphoma → chemo, not surgery).

Differential Diagnosis in Special Populations

Wilms' tumour (most common — 95% of paediatric renal cancers) ^[6]
Neuroblastoma (arises from adrenal/sympathetic chain, can appear as a suprarenal mass — differentiate with urine catecholamines: elevated VMA/HVA in neuroblastoma) ^[6]
Mesoblastic nephroma (neonates — benign)
Clear cell sarcoma of the kidney
Rhabdoid tumour of the kidney (very aggressive; associated with hypercalcaemia) ^[6]

RCC (uncommon but possible)
Translocation RCC (TFE3/TFEB) — usually affects children and young adults; distinct molecular pathology ^[5]
Renal medullary carcinoma — very aggressive, mostly in young patients with sickle cell trait ^[5]
AML (especially if TSC)

Always consider renal metastasis from lung, breast, GIT, prostate, melanoma ^[2]^[3]
Always consider lymphoma (especially if bilateral, homogeneous, with lymphadenopathy)

Category	Diagnosis	Key Distinguishing Feature
Benign	Simple cyst	Anechoic, smooth wall, no enhancement (Bosniak I–II)
	Angiomyolipoma	Fat on CT (HU < −20); a/w TSC
	Oncocytoma	Central stellate scar; cannot distinguish from chromophobe RCC on imaging
	Infection (abscess, XGP)	Fever, leucocytosis, UTI history
	Pseudotumour	Enhances like normal cortex
Malignant — primary	RCC	Most common; cortical, enhancing, heterogeneous
	Urothelial CA of renal pelvis	Central filling defect, hydronephrosis, +ve cytology
	Wilms' tumour	Children; large smooth mass; WAGR/BWS associations
	Collecting duct / medullary CA	Central location; aggressive; sickle cell trait (medullary)
	Translocation RCC	Young adults; TFE3/TFEB rearrangement
	Renal sarcoma	Rare; large heterogeneous mass
Malignant — secondary	Renal metastasis	Multiple, bilateral, borderline enhancement; known primary ^[3]
	Lymphoma	Multiple, bilateral, homogeneous; ± other lymphoma features ^[3]
Non-neoplastic	Renal infarct	Wedge-shaped; clinical context (AF, endocarditis)
	Haematoma	High-density non-enhancing; history of trauma/anticoagulation
	Renal TB	Calcified "putty kidney"; sterile pyuria; EMU for AFB

High Yield Summary

Not all renal masses are RCC — ~20% of renal masses are benign (angiomyolipoma, oncocytoma, simple cysts).
Key imaging feature for AML: macroscopic fat on CT (HU < −20). Key imaging feature for oncocytoma: central stellate scar — but cannot reliably distinguish from chromophobe RCC without histology.
Bosniak classification guides management of cystic renal masses: I–II = benign (no follow-up), IIF = follow-up, III = indeterminate (~50% malignant), IV = treat as malignant.
Urothelial carcinoma of the renal pelvis presents as a central filling defect (not a cortical mass) and requires nephroureterectomy, not nephrectomy alone.
Lymphoma and renal metastasis are treated with systemic therapy — biopsy is indicated to confirm before committing to chemotherapy.
CT-guided biopsy is traditionally NOT done for suspected RCC (risk of tumour seeding); it is reserved for when the result would change management (suspected lymphoma, metastasis, or non-malignant cause).
In children: think Wilms' tumour first; differentiate from neuroblastoma with urine catecholamines (VMA/HVA).
In young adults with sickle cell trait: think renal medullary carcinoma (very aggressive, nearly universally fatal).
XGP is the great mimicker of RCC — chronic granulomatous infection that often only gets diagnosed after nephrectomy.

Active Recall - Differential Diagnosis of Renal Masses

References

^[2] Senior notes: felixlai.md (Renal cell carcinoma section) ^[3] Senior notes: Ryan Ho Urogenital.pdf (pp. 145–147, Section 7.3) ^[4] Senior notes: maxim.md (Renal cell carcinoma section) ^[5] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (p. 17 — RCC Subtypes table) ^[6] Senior notes: felixlai.md (Wilms' tumour section) ^[7] Senior notes: Ryan Ho Fundamentals.pdf (pp. 340–345, Section 3.5.1 — Haematuria)

Diagnostic Criteria, Diagnostic Algorithm & Investigation Modalities for Renal Cell Carcinoma

Before diving into investigations, let's establish some first principles that make RCC diagnostically unique:

There is no validated serum tumour marker for RCC — unlike PSA (prostate), AFP/CEA (liver/colon), or CA-125 (ovary). You cannot "screen" with a blood test.
There is no population-level screening programme for RCC — the only exception is annual USG for patients on long-term dialysis with acquired cystic kidney disease (30× risk) ^[3].
Diagnosis is primarily imaging-based — a contrast CT abdomen with characteristic features is usually sufficient to make a clinical diagnosis and proceed directly to surgery.
The definitive tissue diagnosis comes from the nephrectomy specimen itself — i.e., surgery is both diagnostic and therapeutic simultaneously ^[2]^[4].
CT-guided core biopsy is traditionally NOT done due to risk of tumour seeding ^[3]^[4]. Biopsy is reserved for specific situations where the result would change management.

This approach is fundamentally different from, say, breast cancer (where you biopsy first, then operate) or lymphoma (where tissue diagnosis is mandatory before treatment). In RCC, if the imaging is characteristic and the mass is resectable, you skip biopsy and go straight to the operating room.

The pathway differs depending on how the patient presents:

3. Investigation Modalities — Detailed Breakdown

Though not strictly an "investigation," the physical examination provides critical information ^[2]^[7]:

Examination	Finding	Significance
General	Pallor, cachexia, plethora	Anaemia vs. polycythaemia (paraneoplastic EPO); cachexia = advanced disease
Vitals	Hypertension	Paraneoplastic renin production or renal artery compression
Abdominal	Palpable abdominal renal mass, ballotable kidneys ^[2]	Large tumour (usually > 10 cm); firm, smooth, non-tender, moves with respiration
Abdominal	Hepatomegaly	Liver metastasis or Stauffer syndrome
Scrotal	Scrotal swelling suggesting varicocele ^[2]	Left varicocele that fails to empty when recumbent = left renal vein invasion
Lower limbs	Ankle oedema ^[2]	IVC thrombosis or venous compression from tumour or lymph node

There is no single diagnostic blood test for RCC. Bloods serve three purposes: (1) detect paraneoplastic phenomena, (2) assess baseline organ function before surgery, and (3) provide prognostic information.

Investigation	What to Look For	Clinical Rationale
CBC with differentials ^[2]	Anaemia OR erythrocytosis; thrombocytosis	Anaemia = chronic disease (hepcidin-mediated) or haematuria-related iron loss. Erythrocytosis = paraneoplastic EPO production. Thrombocytosis = reactive (IL-6 driven), associated with poorer prognosis
Urinalysis ^[2]	Haematuria (micro or macro)	Tumour invasion into collecting system → RBCs in urine. Non-glomerular pattern (isomorphic RBCs, no casts)
Urine cytology ^[2]	Malignant cells	Sensitivity is low for RCC (better for urothelial carcinoma). Mainly used to exclude concurrent urothelial carcinoma. Positive cytology in a patient with a cortical mass raises the possibility of a concomitant urothelial lesion
LFT ^[2]	Deranged liver function in liver metastasis or Stauffer syndrome	Stauffer syndrome = non-metastatic hepatic dysfunction (raised ALP, GGT, ± bilirubin) without liver mets; reverses post-nephrectomy. If LFTs deranged, you need imaging to differentiate metastatic from paraneoplastic cause
Albumin ^[2]	Low albumin	Nutritional status assessment pre-operatively; hypoalbuminaemia = poor prognosis
RFT ^[2]	Creatinine, eGFR, electrolytes	Baseline renal function should be assessed since patients with preoperative renal dysfunction and those with risk of CKD should be offered partial instead of radical nephrectomy in order to preserve renal function ^[2]. Also detects hyperkalaemia if obstructive uropathy
Serum calcium	Hypercalcaemia	Paraneoplastic: PTHrP production or 1α-hydroxylation of vitamin D ^[1]. If elevated → check PTH (should be suppressed) and PTHrP
Serum LDH ^[2]	Elevated LDH	May be prognostic in metastatic disease ^[2] — included in the MSKCC/IMDC prognostic models for metastatic RCC
Coagulation profile	PT/INR, APTT	Pre-operative baseline; RCC can cause DIC (rare) or hypercoagulable state
ESR/CRP	Elevated	Non-specific; may be raised in paraneoplastic inflammatory response

Why Check RFT Before Surgery?

This is a crucial pre-operative decision point. If a patient has baseline renal impairment (e.g., solitary kidney, bilateral tumours, CKD), you must preserve as much nephron mass as possible. This is why partial nephrectomy (nephron-sparing surgery) is preferred over radical nephrectomy when technically feasible for T1 tumours — to avoid pushing the patient into dialysis-dependent renal failure. The preoperative eGFR directly influences the surgical plan.

This is where RCC is different from most cancers:

Method	Details	When Used
Nephrectomy or partial nephrectomy ^[2]	Used in most cases to obtain tissue for diagnosis. For patients with isolated solid renal masses, resection with either a partial or complete nephrectomy is preferred to biopsy since it provides both diagnosis and definitive treatment	Standard approach for resectable masses with characteristic imaging
Renal mass biopsy (CT or USG guided) ^[2]^[3]	Role of percutaneous biopsy is limited; preoperative needle biopsy is usually not used for resectable renal lesions because of low specificity and concern about tumour seeding of the peritoneum ^[2]	Indications: renal mass of unknown origin suspicious for metastasis, lymphoma, or non-malignant causes; metastatic disease for thermal ablation; patient preference ^[3]
Biopsy of metastatic site ^[2]	Biopsy of a metastatic lesion is occasionally diagnostic and can be used if there is high index of suspicion for a metastatic lesion to kidney since pathological confirmation is required prior to starting systemic therapy. Biopsy of a metastatic site is often easier and more informative than biopsy of the primary tumour	When systemic therapy is planned and tissue is needed for histological subtyping and molecular profiling

Common Exam Mistake — Biopsy in RCC

Students frequently state "biopsy the renal mass" as the first diagnostic step. This is WRONG for suspected RCC. Unlike many other cancers, the standard approach is to proceed directly to surgical resection, which simultaneously provides tissue diagnosis and treatment. Biopsy is only indicated when it would change management — e.g., if you suspect lymphoma (treat with chemo, not surgery), metastasis from another primary, or a non-malignant cause like abscess.

3.4 Radiological Investigations

USG is less sensitive than CT in detecting a renal mass but is useful to distinguish a simple benign cyst from a more complex cyst or a solid tumour ^[2]^[3].

Finding	Appearance	Interpretation
Simple cyst	Round, sharply demarcated with smooth walls; no echoes within the cyst (anechoic); strong posterior wall echo indicating good transmission ^[2]	Benign (Bosniak I) — no further workup needed
Solid mass	Variable echogenicity; hypoechoic halo of tumour pseudocapsule ^[3]	Suspicious → proceed to contrast CT
Cystic cancer	Irregular, thickened walls; complex structure with septa ^[3]	Suspicious → proceed to contrast CT with Bosniak classification
Fat-containing mass	Hyperechoic (bright)	Angiomyolipoma (confirm with CT for macroscopic fat)

Why USG first?

Readily available, no radiation, no contrast, cheap, bedside procedure ^[7]
Excellent for distinguishing cystic vs. solid — this is its main role
Can detect hydronephrosis, cortical thinning, renal size
Limited by operator dependence, body habitus, and inability to assess retroperitoneum well

CT abdomen (renal protocol) with and without contrast is the initial first-line imaging modality for characterising renal masses; it is extremely accurate in staging RCC — 90% accurate ^[2]^[3].

Why CT is so good for RCC:

Provides anatomical detail of the tumour (size, location, relationship to collecting system)
Shows enhancement pattern (key for distinguishing benign from malignant)
Evaluates local invasion (perinephric fat, renal vein, IVC)
Assesses lymph node involvement
Can image the contralateral kidney (bilateral tumours? solitary kidney?)
Detects adrenal gland involvement
One scan stages the tumour (T, N, and partially M)

CT Protocol — Multiphasic Renal CT:

Phase	Timing	What It Shows	Why It Matters
Non-contrast (plain)	Before contrast	Baseline density (HU); detects calcification, fat, haemorrhage	Macroscopic fat (HU < −20) → AML. Calcification in renal mass → suspicious for malignancy
Corticomedullary (arterial) phase	25–70 sec post-contrast	Cortical enhancement; renal arterial anatomy	Shows tumour vascularity; surgical planning (number of renal arteries, variant anatomy)
Nephrographic phase	80–180 sec post-contrast	Homogeneous renal parenchymal enhancement	Best phase for detecting renal masses — RCC enhances differently from normal parenchyma
Excretory (delayed) phase	> 3–5 min post-contrast	Contrast in collecting system	Evaluates relationship of tumour to collecting system; detects urothelial filling defects

Key CT Findings in RCC:

Feature	Finding	Interpretation
Size	54% RCC if < 1 cm, 78% if 1–3 cm, 80% if 3–4 cm, even higher for larger masses ^[3]	Probability of malignancy increases with size
Enhancement	20–70 HU on pre-contrast; hyperenhancing ( > 10–15 HU increase) on post-contrast phase ^[3]	Enhancement = vascular tumour with blood supply → strongly suggestive of malignancy. A simple cyst does NOT enhance
Structure	Complex cystic, thickened/irregular walls ^[3]	Apply Bosniak classification
Necrosis	Central low-density (non-enhancing) area	Common in large tumours; reflects outgrowth of blood supply → central ischaemic necrosis
Calcification	Mottled, central calcification	90% specific for malignancy when central/irregular ^[3]
Venous extension	Tumour thrombus in renal vein or IVC (filling defect in contrast-enhanced vein)	T3a (renal vein), T3b (IVC below diaphragm), T3c (IVC above diaphragm) ^[1]
Perinephric fat stranding	Irregular soft tissue density in perirenal fat	T3a if perinephric fat invaded but still within Gerota's
Lymphadenopathy	Retroperitoneal nodes > 1 cm short axis	N1 if regional nodes involved

The remaining 10% inaccuracy on CT is primarily due to failure to detect oncocytoma, which appears identical to RCC on imaging ^[2].

When CT shows a cystic renal lesion, the Bosniak classification is used to stratify malignancy risk and guide management ^[2]:

Category	CT Features	Malignancy Risk	Management
I	Hairline thin wall; density < 20 HU (similar to water); NO septation, calcification or solid components; NO enhancement ^[2]	~0%	No follow-up
II	Few thin septa (≤ 1 mm); fine calcification; hyperdense cysts < 3 cm; no measurable enhancement	~0%	No follow-up
IIF	More septa; minimally thickened walls; minimal perceived (but not measurable) enhancement; ≥ 3 cm hyperdense cysts	~5–10%	Serial imaging follow-up
III	Thickened irregular walls/septa; measurable enhancement	~50%	Surgical excision or active surveillance
IV	Clearly enhancing soft tissue component adjacent to cystic mass	~90–100%	Surgical excision (treat as malignant)

Bosniak Classification — The Key Principle

The whole system revolves around one question: does the cyst wall or its contents enhance after contrast? Enhancement means blood supply. Blood supply means tissue with metabolic activity. Metabolically active tissue in a cyst = likely neoplasm. A perfectly simple cyst has no blood supply (it's just fluid in a balloon), so it should never enhance.

MRI is generally indicated if suspicious of IVC involvement ^[3].

Indication	Rationale
Suspected IVC tumour thrombus	MRI is superior to CT for delineating the cephalad extent of tumour thrombus in the IVC — i.e., is the thrombus below the hepatic veins? At the level of the hepatic veins? Above the diaphragm? In the right atrium? This determines the surgical approach (abdominal alone vs. thoracoabdominal vs. cardiopulmonary bypass) ^[2]
Contrast allergy or renal impairment	MRI with gadolinium (or non-contrast MRI) avoids iodinated contrast; however, gadolinium carries risk of nephrogenic systemic fibrosis in severe CKD (eGFR < 30)
Pregnancy	No ionising radiation
Characterisation of indeterminate lesions	MRI can better characterise lesions that are equivocal on CT (e.g., haemorrhagic cysts vs. solid tumours) using T1/T2 signal characteristics and diffusion-weighted imaging

IVU has been increasingly superseded by contrast CT abdomen ^[3]^[7].

Findings in RCC: distortion of renal outline and pelvic calyces ± specks of calcification ^[3]^[7]
Limitation: not sensitive for renal lesions < 3 cm ^[7]
Still occasionally used in resource-limited settings

Modality	Indication	Findings in Metastatic RCC
CXR	Baseline; may show cannonball metastases	Multiple well-defined round nodules ("cannonball" mets); solitary pulmonary nodule; pleural effusion; mediastinal lymphadenopathy
CT chest	Standard staging investigation for RCC (ESMO/EAU guidelines) ^[3]	More sensitive than CXR; can detect subcentimetre nodules; lymphangitis carcinomatosis pattern

Indication	Finding	Interpretation
Bone pain, raised serum ALP, or raised calcium	Multiple areas of increased uptake	RCC bony metastases are characteristically lytic — but the bone scan detects the osteoblastic reaction around lytic lesions, so sensitivity is lower than for purely blastic metastases (e.g., prostate). CT or MRI may be more informative
Not done routinely if asymptomatic	—	—

Indication	Finding
Neurological symptoms (headache, seizures, focal deficits)	Ring-enhancing lesions with surrounding vasogenic oedema; often at the grey-white matter junction (haematogenous spread) ^[8]
Not done routinely if asymptomatic	—

Not routinely used in the primary workup of RCC
RCC has variable FDG uptake (clear cell RCC can be FDG-avid or not)
May be useful for:
- Detecting occult metastases in ambiguous cases
- Monitoring treatment response in metastatic disease
- Differentiating recurrence from post-surgical changes

Purpose	Investigation	When
Primary tumour characterisation	CT abdomen and pelvis with contrast (renal protocol)	All patients
Local staging (T stage)	CT abdomen ± MRI (for IVC extent)	All patients
Nodal staging (N stage)	CT abdomen (retroperitoneal nodes)	All patients
Pulmonary metastases (M stage)	CT chest	All patients
Bone metastases	Bone scan or CT/MRI	If symptomatic (bone pain, raised ALP, raised Ca)
Brain metastases	CT or MRI brain	If neurological symptoms
Baseline bloods	CBC, RFT, LFT, Ca, LDH, coagulation	All patients
Urinalysis and cytology	Dipstick, microscopy, cytology	If haematuria is the presenting complaint

The key concept is a two-step process:

Step 1 — Detect and characterise the mass (Is it real? Cystic or solid? Benign or malignant?)

USG → CT with contrast → apply Bosniak if cystic → assess for fat (AML) → assess enhancement (RCC)

Step 2 — Stage the disease (How far has it spread? What is the treatment plan?)

CT chest + CT abdomen/pelvis ± MRI (IVC) ± bone scan ± brain imaging
Baseline bloods for paraneoplastic markers, organ function, and prognosis

Tissue diagnosis comes from the nephrectomy specimen (not pre-operative biopsy) unless biopsy is specifically indicated.

Two widely used prognostic models for metastatic RCC incorporate laboratory values — this is why the blood tests above are so important:

IMDC (International Metastatic RCC Database Consortium) Criteria — "Heng criteria":

Risk Factor	Threshold	Why
Karnofsky performance status	< 80%	Functional status predicts survival
Time from diagnosis to treatment	< 1 year	Early need for therapy = aggressive biology
Haemoglobin	< lower limit of normal	Anaemia = chronic disease / advanced tumour burden
Corrected calcium	> upper limit of normal	Paraneoplastic PTHrP = aggressive biology
Neutrophil count	> upper limit of normal	Neutrophilia = inflammatory tumour microenvironment
Platelet count	> upper limit of normal	Thrombocytosis = IL-6 driven inflammation

Risk Group	Number of Factors	Median OS
Favourable	0	~43 months
Intermediate	1–2	~23 months
Poor	3–6	~8 months

The IMDC model guides the choice of first-line systemic therapy in metastatic RCC (immunotherapy-based combinations for intermediate/poor risk; TKI or immunotherapy for favourable risk).

High Yield Summary

There is no serum tumour marker for RCC — diagnosis is imaging-based.
CT abdomen with contrast (renal protocol) is the gold standard — 90% accuracy for characterising and staging RCC.
Enhancement > 10–15 HU on post-contrast CT differentiates solid tumour from simple cyst — this is the single most important imaging feature.
Bosniak classification stratifies cystic renal lesions: I–II = benign, IIF = follow-up, III–IV = surgical excision.
MRI is indicated when IVC involvement is suspected — to determine the cephalad extent of tumour thrombus (determines surgical approach).
Tissue diagnosis comes from the nephrectomy specimen — pre-operative biopsy is NOT standard for resectable masses.
Biopsy indications: suspected lymphoma, suspected metastasis from another primary, non-malignant differential, before thermal ablation, patient preference.
Staging workup: CT chest (all patients), bone scan (if symptomatic), brain imaging (if neurological symptoms).
Baseline bloods serve three functions: detect paraneoplastic syndromes (Ca, Hb, EPO), assess organ function pre-operatively (RFT for surgical planning), and provide prognostic information (IMDC criteria: Hb, Ca, neutrophils, platelets).
RFT is critical pre-operatively — baseline renal function determines whether partial nephrectomy (nephron-sparing) should be preferred over radical nephrectomy.

Active Recall - Diagnosis and Investigations for RCC

References

^[1] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (pp. 15, 17, 18) ^[2] Senior notes: felixlai.md (Renal cell carcinoma section — Diagnosis) ^[3] Senior notes: Ryan Ho Urogenital.pdf (pp. 145–147, Section 7.3) ^[4] Senior notes: maxim.md (Renal cell carcinoma — Investigations section) ^[7] Senior notes: Ryan Ho Fundamentals.pdf (pp. 343–345, Section 3.5.1 — Haematuria) ^[8] Senior notes: Ryan Ho Neurology.pdf (pp. 161, 164 — Brain Metastasis)

Management of Renal Cell Carcinoma — Algorithm, Treatment Modalities, Indications & Contraindications

The existing IO-based metastatic pathway remains current. Keep three distinctions explicit:

Adjuvant pembrolizumab is for selected clear-cell RCC meeting KEYNOTE-564 recurrence-risk criteria, not every nephrectomy. The trial now shows an overall-survival benefit, in addition to disease-free survival. (KEYNOTE-564 survival analysis.)
Belzutifan is a later-line HIF-2α inhibitor after previous PD-1/PD-L1 and VEGF-targeted treatment for advanced clear-cell RCC; monitor anaemia and hypoxia. It is not simply interchangeable with every first-line IO/TKI regimen. (FDA indication.)
Cytoreductive nephrectomy is selective: patients who need prompt systemic therapy, especially poor-risk patients, should not automatically undergo immediate nephrectomy. Histology and IMDC risk guide treatment; renal-pelvis urothelial cancer follows a separate nephroureterectomy/urothelial pathway. (EAU RCC guideline.)

Before we walk through the algorithm, let's establish the fundamental principles that make RCC management unique among solid cancers:

Surgery is the main curative treatment for localised RCC — there is no effective adjuvant chemotherapy, but adjuvant pembrolizumab is now recommended for selected high-risk clear-cell RCC after nephrectomy (KEYNOTE-564 criteria) ^[10]^[12].
RCC is classically resistant to conventional chemotherapy — NO role of chemotherapy in treatment of RCC. The reason: the kidney tubular epithelium from which RCC arises is rich in P-glycoprotein (MDR1), a drug efflux pump that actively pumps out chemotherapeutic agents. Additionally, RCC's disordered vasculature (from VEGF overexpression) paradoxically limits effective drug delivery ^[2].
Radiotherapy is selective, not routine — stereotactic radiotherapy is used for clinically relevant brain/bone metastases and may be offered as stereotactic ablative radiotherapy (SABR/SBRT) for selected cT1 lesions in patients unfit for surgery ^[10].
The immune system matters in RCC — RCC is one of the most "immunogenic" solid tumours. Historically it was one of the few cancers that responded to IL-2 and IFN-α. This immune sensitivity is why modern checkpoint inhibitors (anti-PD-1, anti-CTLA-4) have revolutionised metastatic RCC management.
The VHL/HIF/VEGF pathway is druggable — loss of VHL → HIF-α accumulation → VEGF overexpression → angiogenesis. This is the rational basis for anti-VEGF TKIs and mTOR inhibitors.
Even in metastatic disease, surgery often has a role — "cytoreductive nephrectomy" (removing the primary tumour even when metastases are present) and "metastasectomy" (removing isolated metastases) can improve survival in selected patients ^[3].

3. Management of Localised Disease (Stage I–III)

3.1 Surgical Treatment — The Curative Modalities

"Partial nephrectomy" means removing only the tumour with a margin of normal parenchyma, preserving the rest of the kidney.

Why is this preferred over radical nephrectomy for small tumours?

Studies show non-inferior overall survival compared to radical nephrectomy for T1 disease ^[3]
Better long-term renal function preservation → reduces risk of CKD, cardiovascular morbidity, and metabolic complications (patients who undergo radical nephrectomy lose ~30% of their overall GFR overnight) ^[3]
Up to 20% of resected renal masses turn out to be benign (oncocytoma, AML) — so preserving the kidney when possible avoids unnecessary organ loss ^[3]

Indications ^[2]^[3]:

Category	Indication	Rationale
Absolute	Solitary kidney	No contralateral kidney to compensate — radical nephrectomy would mean dialysis
Absolute	Bilateral tumours	Must preserve function on at least one side
Absolute	Multiple small tumours	Often hereditary (VHL); will likely develop more tumours → preserve nephron mass
Strong relative	Patients with comorbidities that impair renal function or will affect future renal function (e.g., DM, renovascular disease) ^[2]^[3]	These patients are already prone to CKD; losing a kidney pushes them toward dialysis
Elective	Primary tumour ≤ 7 cm (T1 stage) ^[1]^[2]	Standard of care for T1a (≤ 4 cm) and T1b (4–7 cm) when technically feasible

Contraindications ^[3]:

Insufficient volume of remaining parenchyma (tumour too large relative to kidney)
Renal vein thrombosis (tumour thrombus in the vein makes clamping and partial resection hazardous)
Unfavourable tumour location (e.g., central tumour adherent to renal vessels or hilum)
Use of anticoagulants (relative — increases bleeding risk)

Surgical approaches ^[2]^[3]:

Approach	When Preferred
Open	Preferred in difficult cases: solitary kidneys, tumour near the renal hilum ^[2]
Laparoscopic	Technically difficult unless robotic-assisted; comparable outcomes with open approach ^[2]
Robotic-assisted	Increasingly the standard; combines the precision of open surgery with the minimal invasiveness of laparoscopy

Key operative principle: Should examine kidney carefully to exclude synchronous tumour (7%) ^[3] — i.e., during partial nephrectomy, the surgeon must check the rest of the kidney for additional tumour foci (especially in hereditary syndromes like VHL).

"Radical nephrectomy" means removing the entire kidney + Gerota's fascia (the fibrous capsule enclosing kidney and perirenal fat) ± related structures.

What is removed ^[2]^[3]:

Entire kidney
Gerota's fascia with perirenal fat
± Ipsilateral adrenal gland (only if involved — routine adrenalectomy is no longer recommended as there is little risk of adrenal recurrence if not clinically involved) ^[3]
± Regional lymph nodes (extended LN dissection is controversial; usually only in clinically N1 disease or high risk of LN spread) ^[3]

Indications ^[1]^[3]:

Stage	Recommendation
T2 (> 7 cm, confined to kidney)	Laparoscopic radical nephrectomy as standard ^[1]^[3] — lower morbidity than open, similar oncological outcome
T3 (locally advanced)	Open radical nephrectomy as standard ^[1]^[3] — allows better access for vascular control, thrombectomy
T4 (beyond Gerota's fascia)	Radical nephrectomy ± adrenalectomy ^[1]

Key surgical principle: Early ligation of vascular pedicle is important to prevent tumour dissemination; once the artery is occluded, the tumour loses most of its profuse blood supply and massive bleeding during mobilisation becomes less likely ^[2]^[3].

Why early ligation? RCC is one of the most vascular solid tumours (remember: VHL loss → VEGF overexpression → abundant tumour vasculature). If you start mobilising the kidney before controlling the artery, you risk catastrophic haemorrhage AND tumour cell dissemination via disturbed venous outflow.

Procedure	Indication	Details
Venous thrombectomy ^[1]^[3]	T3 disease with renal vein/IVC extension	Simple thrombectomy if thrombus extends up to major hepatic veins; cardiopulmonary bypass ± hypothermic circulatory arrest if thrombus extends above hepatic veins ^[2]^[3]
Ipsilateral adrenalectomy	Only if adrenal involvement on imaging/intraoperatively	Not routinely performed — little risk of adrenal recurrence if not clinically involved ^[3]
Extended LN dissection	Clinically N1 or high risk of LN spread ^[3]	Controversial; staging rather than therapeutic benefit in most cases

Thrombectomy Complexity — From the Renal Vein to the Right Atrium

The surgical approach to tumour thrombus depends entirely on its cephalad extent, which is why MRI is so important preoperatively:

Thrombus Level	Surgical Approach
Renal vein only	Standard radical nephrectomy with venous clamping
IVC below hepatic veins	Abdominal approach; IVC clamping above and below thrombus
IVC at/above hepatic veins	May need liver mobilisation, Pringle manoeuvre
Above diaphragm / right atrium	Cardiopulmonary bypass ± hypothermic circulatory arrest ^[2]^[3] — a combined cardiothoracic + urological procedure

This escalating complexity is why accurate preoperative staging with MRI is essential — it determines whether you need a urologist alone, or a urologist + hepatobiliary surgeon + cardiac surgeon in the same operating room.

Timing	Complication	Mechanism
Operative	Mortality (~2%)	Anaesthetic risk, haemorrhage
	GA complications	Standard anaesthetic risks
	Pneumothorax	Pleural injury (especially with flank/posterior approach to upper pole tumours)
	Injury to neighbouring organs (GI tract, major blood vessels, spleen, pancreas)	Anatomical proximity
Post-operative	Temporary or permanent renal failure	Loss of functioning nephrons; especially if pre-existing CKD or solitary kidney
	Ileus	Retroperitoneal dissection → sympathetic irritation → paralytic ileus
	Wound infection (superficial and deep)	Standard surgical complication

3.2 Non-Surgical Local Treatments

Aspect	Details
Principle	Destroy tumour tissue in situ using extreme heat (RFA, microwave) or cold (cryoablation), without removing the kidney
Indications	Small cortical tumours (≤ 3 cm), especially for frail patients, high surgical risk, solitary kidney, compromised renal function, hereditary or multiple bilateral tumours ^[3]
Approach	Percutaneous (image-guided) or laparoscopic
Pre-procedure	Percutaneous renal biopsy should be done to confirm diagnosis ^[3] — unlike nephrectomy, you won't have a surgical specimen, so you need tissue proof before ablating
Outcomes	Short- and long-term outcomes can be comparable with PN/RN for small tumours ^[3]; however oncological outcomes are inferior to surgery and associated with a higher recurrence rate overall ^[2]
Advantage	Maximal preservation of renal parenchyma and function ^[2]

Why biopsy before ablation? Because with surgery, the removed specimen provides tissue diagnosis. With ablation, nothing is removed — you're destroying the tumour in place. You need to confirm it's actually cancer (and not an oncocytoma or AML) before you ablate it.

Aspect	Details
Rationale	Improved imaging modalities led to increased detection of small renal masses, of which many are slow-growing ^[3]
Indication	Elderly patients with significant comorbidities or short life-expectancy + tumour < 4 cm ^[3]
Protocol	Serial imaging (CT or USG) at regular intervals; intervene if growth > 3–4 mm/year or > 4 cm
Biopsy	Consider renal mass biopsy if the result would change counselling or treatment; biopsy is mandatory before thermal ablation because there will be no surgical specimen ^[10]
Outcome	Slow growth in most cases (mean 3 mm/year); progression to metastatic disease only in 1–2% ^[3]

Why is this safe? Small renal masses (< 4 cm, T1a) have a very low rate of metastasis. In elderly patients with competing comorbidities (heart failure, COPD, etc.), the risk of dying FROM the kidney cancer is lower than the risk of dying WITH it from something else. Surgery carries operative risks that may outweigh the oncological benefit.

SABR/SBRT is no longer just "palliation" in RCC. It may be offered to patients with cT1 renal tumours who have an indication for treatment but are unfit for surgery. Evidence is still less mature than for surgery, so patients should be counselled about uncertainty in long-term oncological outcomes.

NO role of adjuvant chemotherapy following complete resection of localised RCC ^[2].

Current guidelines separate chemotherapy/targeted therapy from adjuvant PD-1 therapy:

Adjuvant chemotherapy — no benefit (RCC is chemo-resistant)
Adjuvant targeted therapy (sunitinib, sorafenib, pazopanib, everolimus, axitinib) — not recommended after nephrectomy because OS benefit has not been shown and toxicity is significant ^[10].
Adjuvant pembrolizumab — offer to selected clear-cell RCC patients, preferably within 12–16 weeks post-nephrectomy after restaging, if they match KEYNOTE-564 recurrence-risk groups: pT2 grade 4 or sarcomatoid, pT3 any grade, pT4, pN+, or M1 no evidence of disease after complete metastasectomy within one year ^[10]^[12].
Other adjuvant/perioperative ICI strategies — atezolizumab, nivolumab, nivolumab + ipilimumab, and perioperative nivolumab have not shown consistent benefit and should not be treated as equivalent to pembrolizumab ^[10].

For lower-risk resected RCC, the standard remains surveillance. For high-risk clear-cell RCC, use shared decision-making because pembrolizumab reduces recurrence risk but can cause immune-related toxicity and overtreatment ^[10].

4. Management of Metastatic Disease (Stage IV)

This is where RCC management has been transformed over the past two decades. Let's build up the logic from first principles.

Before choosing systemic therapy, you must stratify the patient's prognosis. The IMDC (International Metastatic RCC Database Consortium) criteria — also called "Heng criteria" — determine the treatment approach:

Risk Factor	Threshold
Karnofsky performance status	< 80%
Time from diagnosis to systemic treatment	< 1 year
Haemoglobin	< lower limit of normal
Corrected calcium	> upper limit of normal
Neutrophil count	> upper limit of normal
Platelet count	> upper limit of normal

Risk Group	Number of Factors	Implication
Favourable	0	Indolent biology; consider TKI monotherapy or IO-TKI
Intermediate	1–2	Standard biology; combination immunotherapy preferred
Poor	3–6	Aggressive biology; combination immunotherapy preferred

4.2 Local Therapy in Metastatic Disease

Even in metastatic disease, surgery can play a role. This is unusual for most solid cancers.

Aspect	Details
Definition	Removal of the primary kidney tumour in the setting of metastatic disease — not curative unless all disease can be cleared
Indication	Good performance status with no immediate need for systemic therapy, symptomatic primary tumour, or oligometastatic disease where complete local treatment of metastases is achievable ^[10]
Rationale	Can reduce tumour burden and delay systemic therapy in highly selected patients; complete resection of primary + oligometastases may be potentially disease-controlling
Contraindication	IMDC/MSKCC poor risk, high metastatic volume, rapidly progressive disease, poor performance status, or asymptomatic synchronous primary tumour that requires immediate systemic therapy
Evidence	CARMENA showed sunitinib alone was non-inferior to immediate cytoreductive nephrectomy + sunitinib in intermediate/poor-risk patients. Current guidance favours upfront IO-based systemic therapy for intermediate/poor-risk patients who need treatment, with delayed CN considered only if they derive clinical benefit ^[10]

Aspect	Details
Definition	Surgical removal of isolated metastatic deposits
Indication	Favourable-risk patients where complete resection is possible; oligometastatic disease ^[3]
Examples	Pulmonary metastasectomy (lung mets are the most common and most amenable to resection); resection of solitary brain met; bone tumour resection for impending fracture
Alternatives	Stereotactic radiotherapy (SRS/SBRT), surgical removal ^[3]
Adjuvant after metastasectomy	NOT needed ^[3]
Outcome	Increased overall and cancer-specific survival in selected patients ^[3]

Why Can You Resect Lung Metastases in RCC?

This seems counterintuitive — if cancer has already spread, why does removing metastases help? The answer lies in RCC's biology:

RCC metastases can grow slowly (especially in favourable-risk patients)
RCC is chemo-resistant, so you can't rely on systemic therapy to eliminate residual disease
In oligometastatic disease (few, resectable metastases), complete surgical clearance can result in durable remission
Metastasectomy may have a role in selected cases (e.g., RCC, CA colon) ^[9] — lung metastasectomy criteria: surgically resectable, adequate cardiopulmonary reserve, primary tumour controllable

This is different from, say, pancreatic cancer with liver metastases — where the biology is so aggressive that removing metastases provides no benefit because new ones appear immediately.

4.3 Systemic Therapy for Metastatic RCC

Why is RCC responsive to immunotherapy? RCC is one of the most immunogenic solid tumours. Evidence:

Spontaneous regression of metastases after nephrectomy (rare but well-documented)
Historical responses to IL-2 and IFN-α
High tumour mutational burden in many cases → more neoantigens → more immune targets
Rich immune cell infiltrate in tumour microenvironment

Agent	Class	Mechanism	Notes
Nivolumab	Anti-PD-1 ^[1]^[2]^[3]	PD-1 is a "brake" on T cells. Tumours express PD-L1 which binds PD-1 on T cells, telling them to "stand down." Nivolumab blocks this interaction → T cells remain activated → attack tumour	Can be used as monotherapy (2nd line) or in combination
Ipilimumab	Anti-CTLA-4 ^[1]^[3]	CTLA-4 is another immune checkpoint on T cells that suppresses activation. Blocking it → enhanced T cell priming and proliferation	Used in combination with nivolumab
Pembrolizumab	Anti-PD-1 ^[1]	Same mechanism as nivolumab	Used in combination with axitinib or lenvatinib
High-dose IL-2 ^[2]^[3]	Cytokine therapy	Directly stimulates T cell proliferation and activation	Effective with long-term remissions without relapse in a minority; associated with high toxicity often not tolerable ^[2]. Largely superseded
IFN-α ^[2]^[3]	Cytokine therapy	Enhances immune recognition of tumour cells; anti-proliferative	Combined with cytoreductive nephrectomy can improve survival ^[2]; largely superseded by checkpoint inhibitors ^[3]

Current first-line regimens (2024–2026 guidelines):

IMDC Risk	First-Line Regimen	Rationale
Favourable (0 RF)	Pembrolizumab + axitinib, lenvatinib + pembrolizumab, nivolumab + cabozantinib, nivolumab + ipilimumab, or sunitinib/pazopanib ^[10]^[11]	IO-TKI combinations improve PFS/response; OS advantage over sunitinib is less clear in favourable-risk disease, so TKI monotherapy remains acceptable when appropriate
Intermediate/Poor (≥ 1 RF)	Nivolumab + ipilimumab, pembrolizumab + axitinib, lenvatinib + pembrolizumab, or nivolumab + cabozantinib ^[10]^[11]^[12]	IO-based combinations are standard; VEGFR-TKI monotherapy is reserved for patients who cannot receive or tolerate immune checkpoint inhibition

Second-line and beyond:

Line	Options
After IO-based first-line	Cabozantinib or another VEGF-TKI ^[10]
After VEGF-TKI monotherapy first-line	Nivolumab or cabozantinib ^[10]
Later lines	Sequence an active agent not previously used; belzutifan is an alternative to everolimus after second- to fourth-line therapy for clear-cell metastatic RCC ^[10]

These drugs target the VHL/HIF/VEGF axis and the mTOR pathway:

Class	Examples	Mechanism	Key Points
Tyrosine kinase inhibitors (TKIs)	Sunitinib, pazopanib, axitinib, sorafenib, cabozantinib, lenvatinib, tivozanib ^[1]^[2]^[3]^[10]	Block VEGF receptor (and other kinases) → inhibit tumour angiogenesis and proliferation. Since RCC is VEGF-driven (VHL loss → HIF → VEGF), cutting off the blood supply starves the tumour	Single-agent VEGF-TKI first-line therapy has largely been superseded by IO-based combinations, except in favourable-risk disease or when ICI cannot be used. Cabozantinib has the strongest later-line data after IO-based therapy ^[10]
Anti-VEGF monoclonal antibody	Bevacizumab ^[1]^[2]	"Bevacizumab" → "beva" (from "beverage"? No — named by Genentech). It's a humanised monoclonal antibody that binds circulating VEGF → prevents VEGF from binding its receptor → anti-angiogenic	Usually combined with IFN-α; less commonly used now with the advent of IO combinations
mTOR inhibitors	Temsirolimus, everolimus ^[2]^[3]	mTOR (mechanistic target of rapamycin) is a kinase in the PI3K/AKT/mTOR pathway that promotes cell growth and proliferation. In RCC, this pathway is often upregulated. Inhibiting mTOR → reduces cell growth, angiogenesis, and metabolism	Their front-line role has been superseded. Everolimus may be used later line, but belzutifan and VEGF-targeted options are often preferred when available ^[10]
HIF-2α inhibitor	Belzutifan ^[10]	Blocks HIF-2α transcriptional signalling downstream of VHL loss	Later-line option for previously treated clear-cell metastatic RCC; also relevant in VHL-associated disease

Drug name breakdown:

"Suni-tinib" → "-tinib" = tyrosine kinase inhibitor
"Pazo-panib" → "-panib" = pan (many) kinase inhibitor
"Bevaci-zumab" → "-zumab" = humanised monoclonal antibody
"Nivo-lumab" → "-lumab" = fully human monoclonal antibody
"Tems-iro-limus" → "-limus" = mTOR inhibitor (from rapamycin/sirolimus)

Subtype	Recommended Approach
Papillary RCC	Cabozantinib has randomised phase II evidence over sunitinib; lenvatinib + pembrolizumab or nivolumab + cabozantinib are options based on smaller studies ^[10]
Other non-ccRCC	Sunitinib, lenvatinib + pembrolizumab, nivolumab + ipilimumab, or cabozantinib + nivolumab (except chromophobe RCC for the latter) may be offered, recognising weaker evidence ^[10]
Collecting duct / medullary carcinoma	May respond better to platinum-based chemotherapy (behaves more like urothelial carcinoma); renal medullary carcinoma is an exception where cytotoxic combinations remain important ^[10]
Sarcomatoid differentiation	Treat as high-priority for immune checkpoint combination therapy

Modality	Role in RCC
Chemotherapy	NO role for typical clear-cell metastatic RCC due to low response rate and short-lived responses ^[2]^[10]. Exceptions include collecting duct and medullary carcinoma, where platinum-based cytotoxic regimens may be used ^[10]
Radiotherapy	Not routine adjuvant therapy after nephrectomy, but stereotactic radiotherapy is used for brain/bone metastases for local control and symptom relief. SABR/SBRT can be considered for selected cT1 renal tumours when patients are unfit for surgery ^[10]

Stage	T Classification	Standard Treatment	Alternatives
T1 (≤ 7 cm)	T1a ≤ 4 cm; T1b 4–7 cm	Partial nephrectomy ^[1]	Cryotherapy/RFA; SABR/SBRT; active surveillance or watchful waiting for selected frail/comorbid patients ^[10]
T2 (> 7 cm, confined)	T2a 7–10 cm; T2b > 10 cm	Laparoscopic/open radical nephrectomy ^[1]	—
T3 (locally advanced)	Renal vein/IVC/perinephric invasion	Radical nephrectomy + thrombectomy ^[1]	± LN dissection if N+
T4 (beyond Gerota's)	Including ipsilateral adrenal	Radical nephrectomy ± adrenalectomy ^[1]	—
Metastatic (M1)	Any T, any N	IO-based systemic therapy for most clear-cell RCC, based on IMDC risk and patient factors ^[10]^[11]^[12]	± delayed cytoreductive nephrectomy; ± metastasectomy/SBRT for selected oligometastatic disease

After curative-intent surgery, patients need follow-up to detect recurrence:

Risk Level	Surveillance Protocol
High-risk (T3–T4, N+, high grade)	CT every 3–6 months for 2 years, then annually ^[3]
Low-risk (T1–T2, N0, low grade)	CT annually ^[3]

What are you looking for?

Local recurrence in the renal fossa
Contralateral kidney tumour (metachronous)
Distant metastases (lung, bone, liver, brain)
Decline in renal function (especially post-radical nephrectomy)

High Yield Summary

Surgery is the only cure for localised RCC. Partial nephrectomy is standard for T1 (≤ 7 cm); radical nephrectomy for T2 and above ^[1].
Absolute indications for partial nephrectomy: solitary kidney, bilateral tumours, multiple small tumours ^[2].
Early ligation of the vascular pedicle during radical nephrectomy is crucial to prevent haemorrhage and tumour dissemination ^[2]^[3].
IVC tumour thrombus above hepatic veins requires cardiopulmonary bypass ± hypothermic circulatory arrest ^[2]^[3].
NO role for adjuvant chemotherapy after complete resection of localised RCC ^[2]^[3]. Adjuvant pembrolizumab is now offered to selected high-risk clear-cell RCC patients after nephrectomy using KEYNOTE-564 criteria ^[10]^[12].
Chemotherapy has NO role in RCC (P-glycoprotein efflux pump; chemo-resistant) ^[2].
Radiotherapy is selective: stereotactic RT for brain/bone metastases and SABR/SBRT for selected cT1 patients unfit for surgery ^[10].
Metastatic RCC management is guided by IMDC risk stratification ^[3]:
- Favourable: IO-TKI, nivolumab + ipilimumab, or TKI monotherapy depending on patient factors
- Intermediate/poor: IO-based combination therapy (nivolumab + ipilimumab, pembrolizumab + axitinib, lenvatinib + pembrolizumab, or nivolumab + cabozantinib)
Cytoreductive nephrectomy is not routine upfront therapy for intermediate/poor-risk patients needing systemic treatment; consider immediate CN only in selected patients or delayed CN after response ^[10].
Metastasectomy improves survival in selected patients with oligometastatic, resectable disease ^[3].
Active surveillance is safe for elderly/frail patients with tumours < 4 cm (mean growth 3 mm/year, 1–2% metastatic progression) ^[3].
Biopsy before thermal ablative therapy (RFA/cryo) is mandatory since no surgical specimen will be available ^[3]^[10].

Active Recall - Management of RCC

References

^[1] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (p. 19 — RCC Treatment) ^[2] Senior notes: felixlai.md (Renal cell carcinoma — Treatment section) ^[3] Senior notes: Ryan Ho Urogenital.pdf (pp. 148–149, Section 7.3.1 — Management) ^[7] Senior notes: Ryan Ho Fundamentals.pdf (p. 345 — Management of urinary tumours) ^[8] Senior notes: Ryan Ho Neurology.pdf (pp. 164–165 — Brain metastasis management) ^[9] Senior notes: Ryan Ho Respiratory.pdf (p. 150 — Secondary tumours of the lungs) ^[10] European Association of Urology (EAU) Guidelines on Renal Cell Carcinoma, 2026 update. ^[11] NCCN Clinical Practice Guidelines in Oncology: Kidney Cancer, Version 1.2026. ^[12] ASCO Guideline: Management of Metastatic Clear Cell Renal Cell Carcinoma, published 2023, reviewed/updated 2026.

Complications of Renal Cell Carcinoma

Complications of RCC can be divided into three broad categories: (A) complications of the disease itself (untreated or progressive), (B) complications of surgical treatment, and (C) complications of systemic therapy. Let's work through each systematically, always connecting back to the underlying mechanism.

1. Complications of the Disease Itself

These are the consequences of the tumour growing, invading, metastasising, and secreting bioactive substances. Many of these overlap with the clinical features discussed earlier, but here we frame them as complications — i.e., things that cause morbidity and mortality.

Complication	Mechanism	Clinical Consequence
Ureteric/pelvicalyceal obstruction	Tumour mass compresses or invades the renal pelvis or ureter → blocks urine drainage	Hydronephrosis → renal function decline on ipsilateral side; if bilateral (rare) or solitary kidney → obstructive renal failure. May present as flank pain
Haemorrhage (spontaneous tumour bleed)	RCC is one of the most vascular tumours (VHL loss → VEGF → abundant neovascularisation). Tumour vessels are fragile and lack normal smooth muscle → prone to spontaneous rupture	Retroperitoneal haemorrhage (Wunderlich syndrome — though more classically associated with AML, RCC can also cause it); gross haematuria with clot retention; haemorrhagic shock (rare)
Direct invasion into adjacent organs	T4 disease — tumour invades beyond Gerota's fascia	Invasion into adrenal gland, liver (right-sided), spleen/pancreas tail (left-sided), diaphragm, psoas muscle, bowel

This is the hallmark complication unique to RCC — the propensity to grow into the venous system as a tumour thrombus.

Complication	Mechanism	Clinical Consequence
Left varicocele ^[1]	Left renal vein invasion → obstructs left gonadal vein outflow	Non-reducible left scrotal swelling; infertility (secondary to heat from varicocele)
Lower limb oedema ^[1]	IVC tumour thrombus → obstructed venous return from lower limbs	Bilateral leg swelling, may be massive
Ascites	IVC obstruction → hepatic vein congestion → Budd-Chiari-like picture → transudative ascites	Abdominal distension, shifting dullness
Pulmonary embolism ^[1]	Tumour thrombus fragments can detach and embolise to the pulmonary arteries — just like a DVT/PE but the "clot" is actually tumour	Sudden dyspnoea, pleuritic chest pain, haemoptysis, cardiovascular collapse. Can be the presenting event and can be fatal
Hepatic venous congestion / Budd-Chiari syndrome	IVC tumour thrombus at or above the level of the hepatic veins → hepatic venous outflow obstruction	Hepatomegaly, RUQ pain, ascites, elevated LFTs, portal hypertension

25% of patients have advanced locoregional disease or distant metastasis at presentation ^[2]. The complications depend on the site of metastasis:

Site	Complication	Mechanism	Management
Lung (most common) ^[2]	Respiratory failure, haemoptysis, pleural effusion, airway obstruction	Tumour replaces normal lung parenchyma; erosion into bronchial vasculature; lymphangitis carcinomatosis → severe dyspnoea ^[9]	Systemic therapy; palliative radiotherapy; pleurodesis for effusions; metastasectomy if oligometastatic ^[9]
Bone ^[2]	Pathological fractures, spinal cord compression, hypercalcaemia, bone pain	RCC bone metastases are characteristically lytic (osteoclast-activating) and highly vascular — biopsy or even minor trauma can cause significant haemorrhage. Lytic destruction weakens the bone cortex → fracture with minimal force	Bisphosphonates/denosumab (inhibit osteoclast activity); orthopaedic stabilisation; palliative radiotherapy; decompressive surgery for cord compression
Brain ^[8]	Seizures, focal neurological deficits, raised ICP, cognitive dysfunction	Haematogenous spread → usually at grey-white junction (watershed areas where vessel calibre decreases, trapping tumour emboli) ^[8]. Surrounding vasogenic oedema causes mass effect	Dexamethasone (reduce oedema); AEDs if seizures; SRS/surgery for solitary operable lesions; WBRT for multiple lesions ^[8]
Liver ^[2]	Hepatic failure (late), RUQ pain, jaundice	Direct extension (right kidney) or haematogenous spread	Systemic therapy; rarely hepatic resection
Adrenal	Usually asymptomatic; rarely adrenal insufficiency	Contralateral adrenal metastasis (ipsilateral is by direct invasion = T4)	Systemic therapy; adrenalectomy if isolated
Choroid (eye) ^[10]	Visual loss, visual field defects	Haematogenous spread to the highly vascular choroid	Plaque radiotherapy or EBRT ^[10]

Bone Metastases in RCC — A Haemorrhagic Hazard

RCC bone metastases are uniquely hypervascular (remember: the tumour is pumping out VEGF). This means that biopsy of a suspected RCC bone metastasis can cause life-threatening haemorrhage. If a patient with a known renal mass has a lytic bone lesion, do NOT blindly biopsy it without considering pre-operative embolisation or at least being prepared for significant bleeding. Orthopaedic surgeons should be warned.

These affect 6–10% of RCC patients and can cause significant morbidity even without metastatic disease ^[4]:

Paraneoplastic Syndrome	Mechanism	Complication if Untreated
Hypercalcaemia ^[1]^[11]	Most common paraneoplastic syndrome in RCC; caused by tumour secretion of PTHrP ^[1]; also possible via 1α-hydroxylation of vitamin D by tumour cells, or lytic bone metastases ^[11]	Confusion, polyuria, polydipsia, dehydration, constipation, cardiac arrhythmias (shortened QT), renal stones, and in severe cases coma and death. Management: IV NS (rehydration) → bisphosphonate (pamidronate/zoledronic acid) ± calcitonin ^[11]
Polycythaemia ^[1]	Ectopic production of erythropoietin ^[1] (HIF-α drives EPO transcription in VHL-deficient tumour cells)	Hyperviscosity syndrome → thrombosis (DVT, PE, stroke), headache, plethora, visual disturbance. Management: phlebotomy; definitive = treat the tumour
Hypertension ^[1]	Ectopic renin secretion ^[1] → RAAS activation → Na/water retention + vasoconstriction	Accelerated/malignant hypertension → end-organ damage (LVH, renal impairment, retinopathy, stroke). Management: antihypertensives; definitive = tumour resection
Fever, weight loss, and cachexia ^[1]	Cytokine-mediated ^[1] (IL-6, TNF-α, IL-1) → increased BMR, muscle catabolism, anorexia	Progressive debilitation; may mimic infection (FUO workup). RCC is a classic cause of PUO/FUO of neoplastic origin
Stauffer syndrome (nonmetastatic hepatic dysfunction) ^[1]	Unknown exact mechanism — likely IL-6-mediated hepatocyte dysfunction	Deranged LFTs (raised ALP, GGT, ± bilirubin), hepatosplenomegaly, fever — all without liver metastases. Resolves after nephrectomy. If LFTs don't normalise → suspect recurrence or true metastatic disease
Anaemia of chronic disease	Hepcidin upregulation (IL-6 → hepatic hepcidin production → blocks iron export from macrophages → functional iron deficiency)	Fatigue, dyspnoea, reduced exercise tolerance. Iron studies: low serum iron, low TIBC, high ferritin
AA amyloidosis	Chronic inflammation → sustained serum amyloid A (SAA) production → amyloid fibril deposition in kidneys, liver, spleen	Nephrotic syndrome (proteinuria), hepatosplenomegaly, GI dysfunction. Rare but important
Thrombocytosis	Reactive — IL-6-driven hepatic thrombopoietin production	May contribute to hypercoagulable state; associated with poorer prognosis

2. Complications of Surgical Treatment

The lecture slides specifically highlight complications of partial nephrectomy and radical nephrectomy ^[1].

Complication	Mechanism	Details
General anaesthetic risk ^[2]	Standard GA risks	Aspiration pneumonia, atelectasis, cardiovascular events
Bleeding ^[2]	RCC is highly vascular; renal hilum contains large-calibre vessels	Intraoperative haemorrhage; post-operative haematoma. Early ligation of renal artery mitigates this risk
Superficial or deep wound infections ^[2]^[3]	Standard surgical complication	More common in open approach; risk increased by obesity, DM, immunosuppression
Paralytic ileus ^[2]	Retroperitoneal dissection → irritation of sympathetic plexus → temporary bowel dysmotility; especially for the transperitoneal approach; ileus is not common when peritoneal cavity is not entered ^[2]	Abdominal distension, nausea, absent bowel sounds. Usually self-limiting
Pneumothorax ^[2]^[3]	Pleural injury — especially when operating on upper pole tumours via a flank approach, the pleura may be inadvertently entered	Post-op respiratory distress; diagnosed on CXR; managed with chest drain
Injury to adjacent organs ^[2]^[3]^[4]	Anatomical proximity during dissection	Left kidney: spleen, pancreas (tail). Right kidney: liver, gallbladder, duodenum (D2) ^[2]^[4]
Mortality	~2% ^[3]	Higher in T3–T4 disease with IVC involvement requiring complex reconstruction

Complication	Mechanism	Details
Bleeding from the resection bed ^[4]	The cut surface of the remaining kidney is raw and vascular; warm ischaemia time during clamping must be < 30 minutes to avoid ischaemic damage, but this limits haemostasis time	May require re-exploration; use of haemostatic agents (Surgicel, TachoSil)
Urine leakage ^[4]	If the resection margin enters the collecting system and the defect is not adequately repaired	Urinoma formation; may require ureteric stenting or percutaneous drainage
Recurrence in the ipsilateral kidney ^[4]	Positive surgical margin; satellite tumour foci missed at initial surgery (7% synchronous tumours) ^[3]	Requires surveillance; may need completion nephrectomy
Warm ischaemia injury	Renal artery clamping during partial nephrectomy causes temporary ischaemia → if prolonged ( > 25–30 min), risk of irreversible tubular necrosis	Transient or permanent decline in ipsilateral kidney function; mitigated by selective arterial clamping, early unclamping, or cold ischaemia techniques (ice/cold fluid) ^[4]

Complication	Mechanism	Details
Temporary or permanent renal failure ^[2]^[3]	Loss of entire kidney reduces total nephron mass by ~50%; if pre-existing CKD or solitary kidney → high risk of dialysis dependence	This is THE major long-term complication and the reason why partial nephrectomy is preferred for T1 tumours. Post-RN patients have increased long-term risk of CKD stage ≥ 3, cardiovascular disease, and all-cause mortality
Long-term metabolic/cardiovascular consequences	Reduced renal function → hypertension, accelerated atherosclerosis, metabolic syndrome	Lifelong monitoring of RFT; cardiovascular risk factor management

Why Partial Nephrectomy Protects Against CKD

The kidney has limited regenerative capacity. After radical nephrectomy, the contralateral kidney undergoes compensatory hypertrophy (individual nephrons enlarge and increase GFR), but this compensation is incomplete and plateaus. The remaining kidney handles 60–70% of the original total GFR. However, any future insult (diabetes, hypertension, contrast nephropathy, NSAID use) now acts on a single kidney with reduced reserve. This is why partial nephrectomy preserves kidney function better → limits development of long-term metabolic/CVS disorders ^[3].

3. Complications of Systemic Therapy

Modern metastatic RCC treatment involves checkpoint inhibitors and TKIs, both of which have significant toxicity profiles.

The key concept: checkpoint inhibitors work by releasing the brakes on the immune system. The downside is that the activated immune system can attack normal tissues → immune-related adverse events (irAEs).

Organ System	irAE	Mechanism	Management
Skin	Rash, pruritus, vitiligo	T-cell-mediated attack on melanocytes and keratinocytes	Topical steroids; systemic steroids if severe
GI	Colitis, diarrhoea (especially with anti-CTLA-4 agents like ipilimumab)	Immune-mediated inflammation of colonic mucosa	Hold drug; IV steroids; infliximab if refractory
Liver	Hepatitis (raised transaminases)	Immune-mediated hepatocyte destruction	Hold drug; steroids; mycophenolate if refractory
Endocrine	Thyroiditis (hypo > hyperthyroid), hypophysitis, adrenal insufficiency, type 1 DM	Immune destruction of endocrine glands	Hormone replacement (often permanent); steroids for hypophysitis
Lung	Pneumonitis	Immune-mediated alveolar inflammation	Hold drug; high-dose steroids; may be fatal if not recognised early
Renal	Interstitial nephritis	Immune-mediated tubulointerstitial inflammation	Hold drug; steroids
Neurological	Neuropathy, myasthenia-like syndrome, encephalitis	Autoimmune attack on peripheral/central nervous system	Hold drug; steroids; IVIG/plasmapheresis

irAEs — The Rule of Thumb

Anti-CTLA-4 (ipilimumab) → more colitis and hypophysitis. Anti-PD-1 (nivolumab/pembrolizumab) → more thyroiditis and pneumonitis. Combination therapy → higher rate AND severity of irAEs (up to 60% grade 3–4 toxicity with ipilimumab + nivolumab). The key is early recognition: any new symptom in a patient on checkpoint inhibitors should prompt you to think "could this be an irAE?" rather than attributing it to infection or disease progression.

TKIs block VEGF receptors (and other kinases), so their toxicity profile reflects the physiological roles of these receptors:

Side Effect	Mechanism	Details
Hypertension	VEGF normally promotes nitric oxide (NO) production by endothelial cells → vasodilation. Blocking VEGF → reduced NO → vasoconstriction	Very common (up to 40%); dose-limiting; managed with antihypertensives (ACEi/ARB preferred)
Hand-foot syndrome (palmar-plantar erythrodysaesthesia)	Direct toxicity to eccrine glands and capillaries in palms/soles	Painful, erythematous, desquamating skin changes; dose reduction if severe
Diarrhoea	Disruption of intestinal mucosal renewal (VEGF/PDGF involved in GI mucosal homeostasis)	Common; managed with loperamide
Hypothyroidism	Thyroid capillary regression (VEGF required for thyroid vasculature maintenance) → thyroid ischaemia → destructive thyroiditis → eventual hypothyroidism	Monitor TFTs regularly; treat with levothyroxine
Fatigue	Multifactorial (hypothyroidism, anaemia, direct CNS effects)	Very common; most common reason for dose reduction
Mucositis/stomatitis	Direct mucosal toxicity	Oral ulcers; managed with mouthwashes, dose reduction
Cardiac toxicity	LV dysfunction, QT prolongation; VEGF involved in cardiomyocyte survival	Baseline and interval echocardiography; ECG monitoring
Proteinuria/renal toxicity	VEGF is essential for glomerular endothelial health; blocking it → thrombotic microangiopathy in glomeruli	Monitor urinalysis; dose reduce or stop if nephrotic-range proteinuria
Hepatotoxicity	Off-target kinase inhibition in hepatocytes	More common with pazopanib; monitor LFTs regularly
Bleeding/wound healing impairment	VEGF is essential for angiogenesis in wound healing; blocking it impairs vascular repair	Stop TKI before and after surgery (usually 2–4 weeks); risk of bleeding

Side Effect	Mechanism
Pneumonitis (non-infectious)	mTOR inhibition → altered immune regulation → hypersensitivity pneumonitis
Hyperglycaemia	mTOR is downstream of insulin signalling → inhibition disrupts glucose homeostasis
Hyperlipidaemia	mTOR involved in lipid metabolism
Mucositis	Direct mucosal toxicity
Immunosuppression	mTOR is central to T-cell proliferation → increased infection risk

Prognosis is estimated using risk stratification models:

Stage	5-Year Survival (approximate)
Stage I (T1N0M0)	~90–95%
Stage II (T2N0M0)	~75–85%
Stage III (T3/N1)	~50–65%
Stage IV (T4/M1)	~10–20% (improving with immunotherapy)

Favourable prognostic factors: early stage, low nuclear grade, clear cell histology (responds to targeted/IO therapy), complete surgical resection, favourable IMDC risk score.

Unfavourable prognostic factors: sarcomatoid differentiation, collecting duct/medullary histology, high nuclear grade, venous invasion, lymph node involvement, metastatic disease at presentation, poor IMDC risk score.

High Yield Summary

Disease Complications:

Venous invasion (renal vein → IVC → RA) → left varicocele, bilateral LL oedema, ascites, PE, Budd-Chiari syndrome ^[1].
Paraneoplastic syndromes (6–10%): hypercalcaemia (PTHrP — most common), polycythaemia (EPO), hypertension (renin), Stauffer syndrome (non-metastatic hepatic dysfunction — reverses post-nephrectomy), cachexia (cytokine-mediated) ^[1].
Metastatic disease to lung (cannonball mets), bone (lytic, highly vascular — beware haemorrhage on biopsy), brain, liver, choroid ^[2].

Surgical Complications: 4. General: bleeding, pneumothorax (pleural injury), injury to adjacent organs (L: spleen, pancreas; R: liver, D2), paralytic ileus (especially transperitoneal approach), wound infection, mortality ~2% ^[2]^[3]. 5. Partial nephrectomy-specific: bleeding, urine leakage, ipsilateral recurrence ^[4]. 6. Radical nephrectomy-specific: temporary or permanent renal failure — the major long-term concern ^[2]^[3].

Systemic Therapy Complications: 7. Checkpoint inhibitors: immune-related adverse events (colitis, hepatitis, pneumonitis, thyroiditis, hypophysitis, nephritis). 8. TKIs: hypertension, hand-foot syndrome, diarrhoea, hypothyroidism, cardiac toxicity, proteinuria. 9. mTOR inhibitors: pneumonitis, hyperglycaemia, hyperlipidaemia, immunosuppression.

Active Recall - Complications of RCC

References

^[1] Lecture slides: GC 183. Common urological malignancies and their presentations - Nov 7.pdf (pp. 15, 19, 45) ^[2] Senior notes: felixlai.md (Renal cell carcinoma — Complications section) ^[3] Senior notes: Ryan Ho Urogenital.pdf (pp. 148–150, Section 7.3.1 — Complications of nephrectomy) ^[4] Senior notes: maxim.md (Renal cell carcinoma — Management and complications table) ^[8] Senior notes: Ryan Ho Neurology.pdf (pp. 164–165 — Brain metastasis) ^[9] Senior notes: Ryan Ho Respiratory.pdf (p. 150 — Secondary tumours of the lungs) ^[10] Senior notes: Ryan Ho Opthalmology.pdf (p. 59 — Choroidal metastasis) ^[11] Senior notes: Ryan Ho Endocrine.pdf (p. 44 — Hypercalcaemia of malignancy)

High Yield Summary

RCC arises from renal tubular epithelium (most commonly proximal tubule → clear cell type, 70–80%).
Epidemiology: Male > Female, 6th–8th decade, median age 64. In HK: incidence 4.8/100,000.
Major risk factors: Smoking, obesity, hypertension, acquired cystic kidney disease (30× risk in dialysis patients), VHL syndrome, Birt-Hogg-Dubé, hereditary papillary RCC, tuberous sclerosis.
VHL pathway is central: Loss of VHL → HIF-α accumulation → VEGF (angiogenesis), EPO (polycythaemia), PDGF (proliferation). This explains the tumour's hypervascularity, anti-VEGF therapy responsiveness, and chemo-resistance.
Most patients are asymptomatic — 50–60% found incidentally on imaging.
Classic triad (haematuria + flank pain + palpable mass) = late presentation (10–20%).
RCC uniquely invades the renal vein and IVC → left varicocele (non-reducing), bilateral LL oedema, PE, ascites.
Paraneoplastic syndromes (6–10%): polycythaemia (EPO), hypercalcaemia (PTHrP), HTN (renin), Stauffer syndrome (non-metastatic hepatic dysfunction → reversible post-nephrectomy), anaemia of chronic disease.
Most common metastatic sites: Lung (cannonball mets) > bone (lytic, vascular) > liver > brain > lymph nodes.
Histological subtypes: Clear cell (70–80%) > papillary (10–15%) > chromophobe (5–10%) > collecting duct (~1%) > medullary (< 1%, sickle cell trait).

High Yield Summary

Not all renal masses are RCC — ~20% of renal masses are benign (angiomyolipoma, oncocytoma, simple cysts).
Key imaging feature for AML: macroscopic fat on CT (HU < −20). Key imaging feature for oncocytoma: central stellate scar — but cannot reliably distinguish from chromophobe RCC without histology.
Bosniak classification guides management of cystic renal masses: I–II = benign (no follow-up), IIF = follow-up, III = indeterminate (~50% malignant), IV = treat as malignant.
Urothelial carcinoma of the renal pelvis presents as a central filling defect (not a cortical mass) and requires nephroureterectomy, not nephrectomy alone.
Lymphoma and renal metastasis are treated with systemic therapy — biopsy is indicated to confirm before committing to chemotherapy.
CT-guided biopsy is traditionally NOT done for suspected RCC (risk of tumour seeding); it is reserved for when the result would change management (suspected lymphoma, metastasis, or non-malignant cause).
In children: think Wilms' tumour first; differentiate from neuroblastoma with urine catecholamines (VMA/HVA).
In young adults with sickle cell trait: think renal medullary carcinoma (very aggressive, nearly universally fatal).
XGP is the great mimicker of RCC — chronic granulomatous infection that often only gets diagnosed after nephrectomy.

High Yield Summary

There is no serum tumour marker for RCC — diagnosis is imaging-based.
CT abdomen with contrast (renal protocol) is the gold standard — 90% accuracy for characterising and staging RCC.
Enhancement > 10–15 HU on post-contrast CT differentiates solid tumour from simple cyst — this is the single most important imaging feature.
Bosniak classification stratifies cystic renal lesions: I–II = benign, IIF = follow-up, III–IV = surgical excision.
MRI is indicated when IVC involvement is suspected — to determine the cephalad extent of tumour thrombus (determines surgical approach).
Tissue diagnosis comes from the nephrectomy specimen — pre-operative biopsy is NOT standard for resectable masses.
Biopsy indications: suspected lymphoma, suspected metastasis from another primary, non-malignant differential, before thermal ablation, patient preference.
Staging workup: CT chest (all patients), bone scan (if symptomatic), brain imaging (if neurological symptoms).
Baseline bloods serve three functions: detect paraneoplastic syndromes (Ca, Hb, EPO), assess organ function pre-operatively (RFT for surgical planning), and provide prognostic information (IMDC criteria: Hb, Ca, neutrophils, platelets).
RFT is critical pre-operatively — baseline renal function determines whether partial nephrectomy (nephron-sparing) should be preferred over radical nephrectomy.

High Yield Summary

Surgery is the only cure for localised RCC. Partial nephrectomy is standard for T1 (≤ 7 cm); radical nephrectomy for T2 and above ^[1].
Absolute indications for partial nephrectomy: solitary kidney, bilateral tumours, multiple small tumours ^[2].
Early ligation of the vascular pedicle during radical nephrectomy is crucial to prevent haemorrhage and tumour dissemination ^[2]^[3].
IVC tumour thrombus above hepatic veins requires cardiopulmonary bypass ± hypothermic circulatory arrest ^[2]^[3].
NO role for adjuvant chemotherapy after complete resection of localised RCC ^[2]^[3]. Adjuvant pembrolizumab is now an option for selected high-risk clear-cell RCC after nephrectomy using KEYNOTE-564-style criteria.
Chemotherapy has NO role in RCC (P-glycoprotein efflux pump; chemo-resistant) ^[2].
Radiotherapy is selective: stereotactic RT for brain/bone metastases and SABR/SBRT for selected cT1 patients unfit for surgery.
Metastatic RCC management is guided by IMDC risk stratification ^[3]:
- Favourable: IO-TKI, nivolumab + ipilimumab, or TKI monotherapy depending on patient factors
- Intermediate/poor: IO-based combination therapy (nivolumab + ipilimumab, pembrolizumab + axitinib, lenvatinib + pembrolizumab, or nivolumab + cabozantinib)
Cytoreductive nephrectomy is selective: avoid routine upfront CN in poor-risk patients or intermediate-risk patients needing immediate systemic therapy; consider delayed CN after response or immediate CN when all disease can be locally treated.
Metastasectomy improves survival in selected patients with oligometastatic, resectable disease ^[3].
Active surveillance is safe for elderly/frail patients with tumours < 4 cm (mean growth 3 mm/year, 1–2% metastatic progression) ^[3].
Biopsy before thermal ablative therapy (RFA/cryo) is mandatory since no surgical specimen will be available ^[3].

High Yield Summary

Disease Complications:

Venous invasion (renal vein → IVC → RA) → left varicocele, bilateral LL oedema, ascites, PE, Budd-Chiari syndrome ^[1].
Paraneoplastic syndromes (6–10%): hypercalcaemia (PTHrP — most common), polycythaemia (EPO), hypertension (renin), Stauffer syndrome (non-metastatic hepatic dysfunction — reverses post-nephrectomy), cachexia (cytokine-mediated) ^[1].
Metastatic disease to lung (cannonball mets), bone (lytic, highly vascular — beware haemorrhage on biopsy), brain, liver, choroid ^[2].

Renal Cell Carcinoma

1. Definition

2. Epidemiology

2.1 Global Burden

2.2 Demographics

2.3 Prevalence of Kidney Cancers (for context)

3. Relevant Anatomy and Function

3.1 Gross Anatomy of the Kidney

3.2 Vascular Anatomy (Key for Understanding Spread)

3.3 Lymphatic Drainage

3.4 Metastatic Pathways

3.5 The Gerota's Fascia

4. Etiology and Risk Factors

4.1 Overview

4.2 Modifiable Risk Factors

A. Smoking

B. Obesity

C. Hypertension

D. Occupational/Environmental Exposures

E. Analgesic Use

4.3 Medical Risk Factors

A. Chronic Kidney Disease and Acquired Cystic Kidney Disease

B. Renal Transplantation

C. Chronic Hepatitis C [3]

E. Kidney Stones [3]

F. Prior Kidney Irradiation and Cytotoxic Chemotherapy in Childhood [3]

4.4 Genetic/Hereditary Risk Factors

5. Pathophysiology

5.1 The VHL Pathway — The Central Molecular Story of Clear Cell RCC

5.2 Other Molecular Pathways

5.3 Mechanisms of Paraneoplastic Syndromes

6. Classification

6.1 Histological Classification (WHO)

6.2 TNM Staging (AJCC/UICC 8th Edition, 2017)

6.3 Fuhrman Nuclear Grade (Historical) / WHO/ISUP Grade (Current)

7. Clinical Features

7.1 Overview of Presentation

7.2 Symptoms

A. Incidental Finding on Imaging (50–60%) [4]

B. Classical Triad (10–20% of patients) [4]

C. Symptoms from Venous Extension

D. Metastatic Symptoms

E. Constitutional/Systemic Symptoms

7.3 Signs

A. General Examination

B. Abdominal Examination

C. Scrotal Examination

D. Lower Limbs

7.4 Summary of Clinical Features by Category

8. Benign Renal Masses (Important Differential — Brief Overview)

Active Recall - Renal Cell Carcinoma (Part 1)

References

Conceptual Framework

Differential Diagnoses of Renal Masses — Detailed Breakdown

A. Benign Renal Masses

B. Malignant Renal Masses (Other Than RCC)

C. Non-Neoplastic Conditions Mimicking a Renal Mass

Key Differentiating Principles — Why the Distinction Matters

Differential Diagnosis in Special Populations

Children (< 15 years)

Young Adults (15–40 years)

Adults with Known Malignancy

Approach to Differentiating Renal Masses on Imaging — Practical Summary

Summary Table — Differential Diagnosis of a Renal Mass

Active Recall - Differential Diagnosis of Renal Masses

1. Diagnostic Principles — "There Is No Screening Test and No Serum Tumour Marker"

2. Diagnostic Algorithm

3. Investigation Modalities — Detailed Breakdown

3.1 Bedside / Physical Examination

3.2 Laboratory Investigations (Biochemical Tests)

3.3 Tissue Diagnosis

3.4 Radiological Investigations

A. Ultrasonography (USG) — Initial / Screening Role

B. CT Abdomen and Pelvis with Contrast — The Gold Standard

C. Bosniak Classification of Cystic Renal Masses

D. MRI Abdomen

E. IVU (Intravenous Urogram) — Largely Historical

F. Chest Imaging — For Staging

G. Bone Scintigraphy (Bone Scan)

H. CT or MRI Brain