GC055 Generalized Lymphadenopathy

^[3][4]

M/30, good past health, fever and rash for 3 days after hiking. Generalized LN 1-2 cm; liver edge and spleen tip palpable. CBC: mild thrombocytopenia, slightly low Hb. LDH 350. ^[1]

Key teaching points:

• Peripheral blood film showed atypical lymphocytes. ^[1]
• What the slide image shows: large pleomorphic reactive lymphocytes with abundant deeply basophilic cytoplasm that scallops around adjacent red cells. The population is heterogeneous, unlike the monotonous blasts of acute leukaemia. Morphology is a clue, not a stand-alone diagnosis.
• The lecture then lists the differential diagnoses of atypical lymphocytosis / infectious mononucleosis-like syndrome: ^[1]

Viral infections (EBV, CMV, HIV, acute viral hepatitis); Bacterial (atypical organisms e.g. Mycoplasma pneumoniae, Legionella pneumophila, Salmonella sp., Rickettsia sp.); Mycobacterial (disseminated TB); Dimorphic fungi (Talaromyces marneffei); Parasitic (Toxoplasma gondii); Drug reactions / hypersensitivity.

N.B. Acute lymphoblastic leukaemia may mimic this (especially if the blood film is not carefully assessed). ^[1]

Investigation workup shown in Case 1 ^[1]:

• CXR clear, blood culture no growth, sputum AFB negative
• Mycoplasma serology non-reactive
• CMV IgG+/IgM- (past infection, not acute)
• CMV pp65 negative (reported in the historical case; this assay is not a routine first-line test for an immunocompetent mononucleosis-like illness)
• Monospot test and EBV serology negative (heterophile tests can be falsely negative early and are less reliable in children; interpret an EBV-specific panel in relation to illness timing)
• Widal's test negative (a historical lecture-era test; a negative result does not reliably exclude enteric fever)
• HIV 1/2 Ab negative (a historical antibody-only result does not exclude very early acute HIV; current evaluation starts with a fourth-generation Ag/Ab assay, adding HIV RNA when acute infection is strongly suspected)
• Toxoplasma serology non-reactive
• Urine for Legionella Ag negative

Diagnosis: Orientia tsutsugamushi antibody titre: 256 on admission, 1024 at week 2. Dx = Scrub typhus. An eschar was present on his left inner thigh. ^[1]

Reading the visual sequence: the titre rises exactly fourfold (256 → 1024), providing paired-serum evidence of recent infection; the accompanying clinical photograph localises the inoculation eschar in a site that could easily be missed without a complete skin examination.

Why is this important? Generalized lymphadenopathy after hiking in an endemic region can be caused by mite-borne scrub typhus. A ≥4-fold rise between properly timed acute and convalescent antibody titres supports the diagnosis, but confirmation is retrospective. Early disease is better sampled with PCR from an eschar swab/tissue or whole blood where available. An eschar is a highly useful clue but is neither invariably present nor unique to scrub typhus. When clinical suspicion is high, treatment should not wait for convalescent serology; doxycycline is first-line. ^[16]

M/62, easy bruising 2 weeks. Generalized LN 2-3 cm, hepatosplenomegaly. Platelet count 3 × 10⁹/L (profoundly thrombocytopenic). LDH 550. ^[1]

Peripheral blood film findings ^[1]:

• Numerous "smear" or "smudge" cells — fragile lymphocytes disrupted during film preparation. They are common in CLL but not pathognomonic; diagnosis requires a persistent clonal B-cell lymphocytosis with the appropriate flow phenotype. ^[17]
• Abnormal small-to-medium sized lymphoid cells with high N/C ratio, round nuclei, condensed chromatin, no nucleoli, smooth cytoplasmic border
• No polychromasia, no spherocytes, no rouleaux
• Genuine thrombocytopenia with occasional giant platelets

What the slide image shows: a monotonous background of small mature-appearing lymphocytes with coarsely clumped chromatin, punctuated by numerous pale streaked smudge-cell remnants. The striking paucity of platelets is real; occasional large platelets suggest increased peripheral turnover, but the film alone cannot separate immune destruction from marrow infiltration.

Further investigations ^[1]:

• Multiparametric flow cytometry: CD19+, CD5+, CD23+, CD20 (dim), surface Ig (dim), CD79b (dim). T-cell and NK markers negative.
  • This is the classic CLL immunophenotype: CD5+/CD19+/CD23+ with dim CD20 and dim surface immunoglobulin
• BMA + trephine: heavy infiltration by abnormal lymphoid cells
• Cytogenetics: normal karyotype
• FISH: del(17p) consistent with TP53 loss → adverse risk
• Platelet serology: antibodies against GpIb/IX and GpIIb/IIIa were reported in the case. This can support immune thrombocytopenia in a difficult case but is not a primary or definitive diagnostic test; CLL-related marrow failure, drugs, infection and other causes still require clinical/marrow correlation. ^[18]
• PET-CT: generalized LN and hepatosplenomegaly with low-level FDG uptake in this case. Uptake intensity can help target biopsy but cannot by itself classify a lymphoma as indolent or exclude transformation.

Staging and Management ^[1]:

• The slide labels this Binet stage C because the platelet count is < 100 × 10⁹/L. Important nuance: Rai/Binet staging does not distinguish immune cytopenia from marrow-failure cytopenia, so document the mechanism rather than assuming all thrombocytopenia reflects tumour burden. ^[19]
• Adverse risk due to TP53 loss → del(17p) and/or a pathogenic TP53 mutation predicts poor response to chemoimmunotherapy; both FISH and TP53 sequencing should be checked before each treatment line. ^[19]
• The historical case used ibrutinib and, after progression, obinutuzumab + venetoclax, achieving CR.

Why TP53 matters: TP53 is the "guardian of the genome." When cells are treated with cytotoxic chemotherapy, DNA damage occurs, and TP53 is needed to trigger apoptosis. If TP53 is deleted/mutated, the leukaemia cells cannot undergo p53-mediated apoptosis → chemoresistance. This is why targeted agents (BTK inhibitors, BCL-2 inhibitors) that bypass the p53 pathway are needed.

CLL Key Facts from Lecture ^[1]:

• Most prevalent lymphoid malignancy in North America and Europe; less common in Asians
• Median age 72 years; M:F = 2:1
• Usually diagnosed incidentally (asymptomatic lymphocytosis or LAD/splenomegaly)
• Only ~20% have symptomatic disease at diagnosis
• Staging: Binet staging / Rai Staging
• May transform to aggressive large cell lymphoma = Richter transformation ^[5][6]

M/63, weight loss, rapidly enlarging bilateral cervical LN for 1 month. LN 3-5 cm, firm, non-tender. CBC/LRFT/electrolytes normal. LDH and urate grossly elevated. ^[1]

Why LDH and urate are elevated: High LDH reflects high cell turnover and tissue destruction by rapidly proliferating tumour cells. High urate reflects high purine catabolism from rapid cell turnover. Both are markers of aggressive lymphoma and risk factors for tumour lysis syndrome (TLS).

Diagnostic Investigation — Histology ^[1]:

1. Effaced nodal architecture
2. Sheets of large abnormal lymphoid cells
3. IHC: CD19+, CD20+, CD79a+, PAX5+. T-cell and NK cell markers negative.
4. Consistent with DIFFUSE LARGE B-CELL LYMPHOMA

What the histology image shows: the normal follicular architecture has disappeared and is replaced by a diffuse sheet of discohesive large lymphoid cells with vesicular chromatin and conspicuous nucleoli. This is the architectural and cytological meaning of “diffuse large B-cell”; the B-lineage IHC panel then establishes lineage, while MYC/BCL2/BCL6 testing and the full clinicopathological context refine classification and risk.

Simple cytological assessment (e.g. fine-needle aspirations) are NOT acceptable ^[1]

Staging and Pre-treatment Workup ^[1]:

• PET-CT: hypermetabolic LN in bilateral cervical, thoracic, and intraabdominal regions
• BM biopsy: not involved
• Ann-Arbor Stage IIIB (both sides of diaphragm, B symptoms = weight loss)
• ECG + Echo: normal (pre-treatment cardiology baseline for anthracycline)
• HBsAg positive → risk of HBV reactivation with rituximab-containing immunosuppression
• HBV DNA undetectable
• G6PD normal (for co-trimoxazole prophylaxis)

Treatment ^[1]:

• Entecavir prophylaxis started (antiviral to prevent HBV reactivation)
• R-CHOP: Rituximab + Cyclophosphamide + Doxorubicin (Hydroxyl-daunorubicin) + Vincristine (Oncovin) + Prednisolone
• Achieved CR after 3 cycles, completed 6 cycles, remained in CR

Current staging and treatment caveats: PET-CT is the standard baseline/response modality for FDG-avid DLBCL. Routine marrow biopsy is usually unnecessary when PET-CT has been performed, unless a discordant indolent lymphoma or another marrow disorder is suspected and the result would change management. ^[22][23] First-line therapy remains curative: R-CHOP is appropriate for many patients, while polatuzumab-R-CHP is an evidence-based alternative for selected intermediate/high-risk advanced LBCL. Primary refractory disease or relapse within 12 months is commonly taken directly to second-line CAR-T when eligible; later chemosensitive relapse may still proceed through salvage therapy to autologous transplant. ^[23]

For HBV, screen HBsAg, total anti-HBc and anti-HBs before systemic anticancer therapy. HBsAg-positive patients and patients with past HBV receiving anti-CD20 therapy need antiviral prophylaxis (entecavir or tenofovir are high-barrier options) started before/at therapy and continued for at least 12 months after anti-CD20 treatment, with HBV DNA/ALT monitoring; local hepatology guidance may extend this interval. ^[24]

DLBCL Key Facts from Lecture ^[1]:

• 30% of all NHLs
• Subclassification: GCB vs ABC molecular subtype
• Nodal > extranodal presentation; BM involvement < 10%
• ~2/3 of patients are cured
• Prognostic factors: IPI (clinical), MYC rearrangement (genetic)
• The slide-era sequence was auto-HSCT for chemosensitive relapse; CAR-T for R/R CD19+ DLBCL. Current sequencing moves CAR-T into second line for eligible primary-refractory or ≤12-month relapsed disease. ^[23]

F/35, dry cough 2 months, fever, night sweats, weight loss 10 kg over 2 months. Non-smoker, good past health. 3 cm left supraclavicular fossa LN, rubbery, non-tender. No hepatosplenomegaly. ^[1]

What the imaging shows: the frontal CXR has marked right paratracheal/anterior mediastinal widening with relatively clear lung fields. CT then demonstrates a bulky anterior mediastinal soft-tissue mass encasing or closely abutting the great vessels; this explains the cough and signals the need to assess airway, vascular and SVC compromise before sedation or biopsy. The lecture lists the differential diagnoses of a mediastinal mass:

1. LN — lymphoma / metastatic LN; 2. Thymoma; 3. Germ cell tumour; 4. Others — retrosternal goitre, dilated aortic arch, neurofibroma ^[1]

Diagnostic Investigation — Histology ^[1]:

1. Distorted nodal architecture with thick fibrotic bands
2. Typical multinucleated Reed-Sternberg cells
3. Prominent infiltration by inflammatory cells (reactive lymphocytes, eosinophils, plasma cells)
4. CD20 negative, CD15+, CD30+, T- and NK-cell markers negative

What the histology image shows: broad collagen bands divide the node into nodules. Scattered lacunar/Hodgkin–Reed–Sternberg-type cells sit within a mixed reactive background rich in small lymphocytes, eosinophils and plasma cells. The malignant cells are the minority; the fibrous architecture plus the phenotype supports nodular-sclerosis classical Hodgkin lymphoma.

Dx = Nodular Sclerosis Classical Hodgkin Lymphoma, Ann Arbor Stage IIB ^[1]

Why fibrotic bands + RS cells + mixed inflammatory infiltrate = NS cHL: The RS cells are the malignant cells but comprise < 1% of the tumour mass. The bulk is reactive inflammatory cells. In NS subtype, collagen bands divide the tumour into nodules. RS cells secrete cytokines that recruit eosinophils, T cells, and plasma cells. This is why the biopsy looks "busy" with mixed inflammatory cells.

Pre-treatment workup ^[1]:

• CBC showed eosinophilia (common in cHL due to IL-5 secretion by RS cells)
• LDH and urate elevated
• Baseline ECG, echocardiogram (for anthracycline = doxorubicin/adriamycin)
• Lung function studies (for bleomycin → pulmonary fibrosis risk)
• HBsAg negative, anti-HBs positive, anti-HBc negative → vaccinated/immune, no reactivation risk
• Oocyte preservation before starting chemotherapy (fertility preservation in young woman)

Treatment in the lecture case: ABVD ^[1]

Supportive measures ^[1]:

• Adequate hydration + febuxostat (xanthine oxidase inhibitor) was used in this high-burden case for TLS prophylaxis; contemporary prophylaxis is risk-adapted (hydration plus allopurinol or rasburicase according to risk, renal function and urate)
• Regular CBC and LRFT monitoring
• Interim PET-CT after 2 cycles → CR achieved
• End-of-treatment PET-CT after 4 cycles → continued remission

Relapse and Salvage ^[1]:

• Relapsed 8 months after remission
• Brentuximab vedotin (anti-CD30 mAb linked to MMAE via a protease-cleavable linker) — an antibody-drug conjugate (immunoconjugate). CD30 is expressed on RS cells. Upon binding CD30 and internalisation, the linker is cleaved intracellularly, releasing MMAE (monomethyl auristatin E), a microtubule-disrupting agent that causes cell-cycle arrest and apoptosis. Additional mechanisms include a bystander effect on adjacent tumour cells, antibody-dependent cellular phagocytosis by macrophages, and immunogenic cell death via endoplasmic reticulum stress. ^[1]
• Failed after 3 cycles
• Pembrolizumab (anti-PD1 checkpoint inhibitor) as salvage → achieved CR after 4 cycles

The slide records an individual historical sequence, not a universal salvage algorithm. Relapsed/refractory cHL is now planned around timing of relapse, transplant fitness and prior exposure; salvage therapy is usually used to achieve metabolic response before autologous transplant in eligible patients, while PD-1 blockade and brentuximab-containing strategies may be used before or after transplant. ^[25][26]

Why checkpoint inhibitors work in cHL: RS cells characteristically overexpress PD-L1 (through amplification of 9p24.1 which encodes PD-L1 and PD-L2). This allows RS cells to "hide" from T cells by engaging PD-1 on T cells and sending an inhibitory signal. Anti-PD1 (pembrolizumab) blocks this interaction, unleashing the T-cell anti-tumour response.

This slide maps lymphoma subtypes to their cell of origin in B-cell development:

How to read the B-cell maturation diagram: progenitors mature in marrow, naïve B cells populate the follicular mantle, antigen drives a germinal-centre reaction (centroblast → centrocyte with somatic hypermutation/class switching), and selected cells leave as memory B cells or plasma cells. The neoplasms line up with these compartments: lymphoblastic disease before maturation; mantle cell/part of CLL before the germinal centre; follicular, Burkitt and some DLBCL in the germinal centre; and marginal-zone, lymphoplasmacytic and plasma-cell neoplasms after it. This is a conceptual cell-of-origin map, not proof that each entity has a single linear origin.

How to read the T/NK diagram: T-cell progenitors migrate from marrow to thymus, pass through a CD4+/CD8+ stage, then leave as naïve CD4 or CD8 cells that become effector/memory cells after antigen exposure. NK cells arise outside that thymic αβ T-cell route. Thus T-lymphoblastic lymphoma maps to precursor thymocytes, while most T/NK lymphomas map to mature peripheral compartments.

Current taxonomy is the integrated WHO-HAEM5 framework: morphology, immunophenotype, genetics, clinical setting and anatomic site all contribute to the final entity. The slide's high-grade/low-grade tree is useful for behaviour, but it is deliberately not a substitute for formal WHO classification. ^[27]

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1. Accurate diagnosis
2. Staging
3. Detect complications of lymphoma
4. Determine prognosis
5. Determine suitability or fitness for treatment
6. Detecting complications of treatment
7. Assessing response to treatment

• Anti-CD20 (slide 41): the antibody Fab binds CD20 while its Fc recruits immune killing. The diagram separates complement-dependent cytotoxicity (C1q → membrane attack complex), antibody-dependent cellular cytotoxicity/phagocytosis through Fc receptors, and direct pro-apoptotic signalling. Different anti-CD20 antibodies bind different CD20 epitopes and are not interchangeable merely because the target is shared.
• Brentuximab vedotin (slide 42): anti-CD30 targeting causes internalisation; lysosomal cleavage releases MMAE, which disrupts microtubules and causes mitotic arrest/apoptosis. Free payload can contribute a local bystander effect. This is targeted delivery, not an immune checkpoint drug.
• Checkpoint maps (slides 43–44): antigen recognition through TCR–MHC is surrounded by activating and inhibitory receptors. PD-L1/PD-L2 engagement of PD-1 applies an inhibitory brake; anti-PD-1 or anti-PD-L1 blocks that brake and restores antitumour T-cell function. It does not bind the tumour antigen in the way rituximab or brentuximab does.
• CAR-T (slides 45–47): an antibody-derived scFv binds a surface antigen without MHC presentation; a hinge/transmembrane region anchors the receptor; CD28 or 4-1BB provides co-stimulation; CD3ζ supplies the activation signal. The manufacturing loop is leukapheresis → T-cell selection/engineering → ex-vivo expansion and release testing → lymphodepleting chemotherapy → infusion and toxicity monitoring. The slide's simplified loop omits manufacturing time, bridging therapy and the risks of CRS, ICANS, infection and prolonged cytopenia.

Adoptive cell therapy with T cells genetically engineered to express a CAR. CAR is a recombinant receptor construct consisting of: (1) extracellular single-chain variable fragment (scFv) of an antibody recognizing a tumor-associated cell surface antigen; (2) a spacer or hinge plus transmembrane region; and (3) intracellular co-stimulatory (CD28 or 4-1BB) and CD3ζ signalling domains. ^[1]

The CAR structure also includes a costimulatory signalling domain (CD28 or 4-1BB) between the hinge and the CD3ζ chain, which enhances T-cell activation and persistence. ^[1]

CAR-T manufacturing process ^[1]:

1. Patient's blood cells are collected and T cells are isolated
2. T cells are genetically modified to express the CAR
3. CAR-T cells are expanded ex vivo
4. CAR-T cells are infused back into the patient for treatment

The key side effects to know: Cytokine release syndrome (CRS) — massive cytokine release causing fever, hypotension, hypoxia, multi-organ dysfunction. Neurotoxicity (ICANS) — confusion, seizures, cerebral oedema.

• 10% of all lymphoma cases
• Bimodal age distribution: peak in early 20s and mid-70s
• Slight male predominance
• Usually presents with painless lymphadenopathy involving neck and chest
• B symptoms in advanced disease
• Majority cured with combination chemotherapy ± radiation
• Classical cHL (95%): CD15+, CD30+; subtypes: NS (70%, equal M/F, age 15-35, mediastinal), MC, LR, LD
• NLPHL (5%): "popcorn cells", CD20+, very rare

• 30% of all NHLs; composed of large B cells with diffuse growth pattern
• Subclassification: molecular (GCB/ABC), pathologic, defined entities (primary CNS DLBCL, primary mediastinal large B-cell lymphoma)
• Nodal > extranodal; BM involvement < 10%
• A substantial majority can be cured; R-CHOP remains a standard backbone, with pola-R-CHP used for selected patients ^[23]
• Relapse sequence is timing-dependent: CAR-T in eligible primary-refractory/early-relapse disease; salvage plus auto-HSCT remains important for later chemosensitive relapse ^[23]

• One of the fastest-growing human malignancies; very short doubling time
• Deregulated high-level expression of cMYC from reciprocal translocation: t(8;14), t(2;8), or t(8;22)
• Bulky abdominal mass, B symptoms and extranodal disease are important presentations; marrow/CNS involvement varies by epidemiological subtype and disease burden
• Urgent treatment required; prevention of TLS; Rituximab + multi-agent chemo; cure > 80%

• Prototypical and most common indolent lymphoma
• Most patients diagnosed at advanced stage
• The slide's “anti-CD20 + purine analogue/alkylator” line is only one historical treatment frame. Localised disease may be treated with involved-site radiotherapy; asymptomatic low-tumour-burden advanced disease may be observed; symptomatic/high-burden disease uses an anti-CD20-based regimen selected for age, fitness and goals. Not every patient needs immediate systemic therapy.
• Associated translocation: t(14;18) → overexpression of BCL-2 → anti-apoptotic ^[7]

• 3 subtypes: extranodal MZL of MALT type, nodal MZL, splenic MZL
• Associated with chronic antigenic stimulation:
  • Gastric MALT → H. pylori
  • Cutaneous MALT → B. burgdorferi
  • Ocular adnexal MALT → C. psittaci
  • Nodal/splenic MZL → HCV
  • Pulmonary/parotid MALT → Sjögren syndrome
  • Thyroid MALT → Hashimoto thyroiditis

These are epidemiological associations, not one-to-one diagnostic rules; C. psittaci prevalence in ocular adnexal MALT varies markedly by geography. In gastric MALT lymphoma, test for and eradicate H. pylori because antimicrobial therapy can induce lymphoma regression in appropriate disease.

• Indolent B-cell neoplasm; IgM monoclonal gammopathy in blood + clonal lymphoplasmacytic cells in BM
• Symptoms: hyperviscosity (headache, visual changes, mucosal bleeding), cryoglobulinaemia, autoimmune haemolytic anaemia
• BM/tissue infiltration → anaemia, hepatosplenomegaly, LAD
• Autoimmune phenomena: polyneuropathy

• 6% of all NHLs; median age mid-60s; striking male predominance
• Advanced-stage at presentation; extranodal involvement common (BM, PB)
• Peculiar tendency to invade the GI tract — "lymphomatous polyposis" of the large bowel
• Associated translocation: t(11;14) → overexpression of cyclin D1 ^[7]

• Geographical predilection for Asian and South American populations

• Commonly locally invasive, destroying nasal and midline facial structures

• Other non-nasal sites: skin, GI tract, CNS, testes

• Primary nodal presentation is rare

• EBV-driven lymphoma

• What the clinical images show: prominent unilateral periorbital swelling/erythema and a deeply ulceronecrotic palatal–nasal lesion. Together they demonstrate the characteristic angio-destructive midline phenotype; they are not pictures of simple “generalized lymphadenopathy.” ^[1]

• The slide lists SMILE components (dexamethasone, methotrexate, ifosfamide, L-asparaginase and etoposide; cisplatin belongs to other schedules). Current therapy is stage- and fitness-specific and should be specialist-led: localized disease requires involved-site radiotherapy combined with an anthracycline-free L-asparaginase-containing regimen; advanced/extranasal disease uses multi-agent asparaginase-based systemic therapy. Plasma EBV DNA is followed as a response biomarker. ^[28]

• Aggressive NK-cell leukaemia/lymphoma: fever, rash, hepatosplenomegaly, pancytopenia, haemophagocytosis

• LN characteristics: Duration, rate of growth (rapid = aggressive malignancy; waxing-waning = low-grade lymphoma), pain/tenderness
• Constitutional/B symptoms: Fever, night sweats, weight loss > 10% in 6 months
• Localizing symptoms: Sore throat, cough, rash, pruritus, alcohol-induced pain (cHL)
• Exposure: Travel/hiking (scrub typhus, TB), cats (toxoplasmosis), raw meat (toxoplasmosis), insect bites, sexual history (HIV, syphilis), IVDU (HIV)
• Medications: Phenytoin, hydralazine
• Past medical history: Autoimmune disease, immunodeficiency, prior malignancy, transplant

1. Blood: CBC with differential, peripheral blood film, LFT, RFT, electrolytes, LDH, urate, ESR, β2-microglobulin, SPE
2. Microbiology selected by exposure/syndrome: EBV, CMV, fourth-generation HIV Ag/Ab (with HIV RNA when acute infection is suspected), TB testing/cultures, toxoplasma or rickettsial PCR/paired serology as appropriate. Avoid indiscriminate historical panels such as routine Widal testing.
3. Imaging: CXR or targeted ultrasound/CT initially; PET-CT after lymphoma is suspected/confirmed for staging FDG-avid disease and selecting a representative biopsy target
4. Tissue diagnosis: Excisional biopsy preferred; multiple adequate cores if excision is impractical. FNA alone is insufficient for initial classification. ^[21]
5. BM aspiration + trephine: selective rather than automatic in PET-staged HL/DLBCL ^[22][23]
6. Pre-treatment: regimen-specific cardiopulmonary assessment, pregnancy/fertility discussion, three-test HBV screen, HCV/HIV testing, and other safety tests such as G6PD when relevant