Purpura
Purpura is the appearance of red or purple discolorations on the skin caused by bleeding underneath the skin from small blood vessels (capillaries), resulting from defects in platelets, coagulation factors, or vascular integrity.
Murtagh Diagnostic Strategy
| Category | Diagnosis | Key Discriminator | Cantonese Question / Finding | Probability |
|---|---|---|---|---|
| Probability Diagnosis | Senile / actinic purpura | Elderly, forearm/dorsal hand, no ↓PLT | 「瘀斑係咪主要喺手臂外面？」(Forearm distribution in elderly) | ~30% |
| Drug-induced | Temporal link to aspirin/warfarin/NSAID | 「有冇喺食新藥之後先開始出？」 | ~20% | |
| Immune thrombocytopenia (ITP) | Isolated ↓PLT, otherwise well, no splenomegaly | 「除咗瘀斑，其他身體有冇唔舒服？」(If otherwise well → ITP likely) | ~5% | |
| Serious Not To Miss | Acute leukaemia | Pancytopenia, fatigue, infection, splenomegaly | 「有冇發燒、好攰、成日病？」+ check for splenomegaly | ~1% |
| Meningococcaemia | Acutely unwell + fever + rapidly spreading purpura | 「佢係咪好急好快差咗？有冇高燒？」[7] | < 1% | |
| TTP/HUS | Pentad: fever, ↓PLT, MAHA, neuro Sx, renal impairment | 「有冇頭痛意識模糊、小便少咗？」+ check schistocytes on smear | < 1% | |
| DIC | Acutely ill, oozing, ↑PT/APTT, ↓fibrinogen, ↑D-dimer | Clinical setting of sepsis / malignancy / obstetric emergency [4] | < 1% | |
| Pitfalls | Chronic liver disease | Jaundice, spider naevi, ascites, coagulopathy + ↓PLT | Check for stigmata of CLD [5] | ~5% |
| HSP (IgA vasculitis) | Palpable purpura on LL/buttocks + arthralgia + abdo pain + haematuria; normal PLT [3] | 「瘀斑係咪喺腳同pat pat？有冇肚痛關節痛？」 | ~3% | |
| SLE | Malar rash, photosensitivity, oral ulcers, arthralgia, cytopenias | 「面有冇紅疹？怕唔怕曬？口有冇痱滋？」 | ~1% | |
| Masquerades | Drugs (anticoagulants, antiplatelets, chemotherapy) | Drug history | 「有冇食薄血丸、化療藥？」 | ~20% |
| Alcohol / liver disease | Alcohol Hx, deranged LFT | 「飲幾多酒？有冇肝病？」 | ~5% | |
| Trying to Tell Me Something? | Health anxiety / cancer phobia | Fear of leukaemia, anxiety about bruising | 「你最擔心係咩？」 | ~15% |
| Child abuse (NAI) | Bruises in unusual locations, inconsistent history, delayed presentation | 「小朋友點樣整親？」+ check for other injuries [6] | < 1% |
| Time | Task | Cantonese Key Phrases | Why It Scores Marks |
|---|---|---|---|
| 0:00–0:30 | Friendly opening, introduce yourself, set agenda | 「你好，我係X醫生，今日由我幫你睇症。你可以話俾我聽今日嚟有咩嘢唔舒服？」(Hello, I'm Dr X, tell me what brought you in today) | Scores interpersonal rapport; establishes structure |
| 0:30–2:00 | HPI: explore purpura – onset, distribution, progression, associated symptoms (bleeding, joint pain, abdo pain, fever) | 「呢啲瘀斑係幾時開始㗎？喺邊度出？有冇愈嚟愈多？有冇牙肉出血、流鼻血？有冇關節痛、肚痛？」 | Core symptom analysis; distinguishes platelet vs coagulation vs vasculitis |
| 2:00–3:00 | Red flags & systemic review: headache/neuro Sx, haematuria, weight loss, recurrent infections, night sweats | 「有冇頭痛、頭暈？有冇血尿？近排有冇瘦咗、夜晚出汗？」 | Rules out serious causes – leukaemia, TTP, meningococcal |
| 3:00–4:00 | PMHx, drug Hx, family Hx, social Hx | 「你以前有冇長期病？有冇食緊薄血丸、阿士匹靈？屋企人有冇出血問題？你做咩工作？飲唔飲酒？」 | Drugs (aspirin, warfarin, NSAID) and liver disease are key masquerades |
| 4:00–5:00 | ICE – uncover hidden agenda | 「你自己覺得呢啲瘀斑係咩原因呢？（Idea）你最擔心啲咩？（Concern）你今日最希望我幫到你啲咩？（Expectation）」 | Directly maps to Case Report Form Q3; scores patient-centredness |
| 5:00–5:30 | Summarise & check understanding | 「等我總結吓：你話兩個禮拜前開始發現腳有啲唔甩色嘅紅點，冇痛，有少少關節痛…我講得啱唔啱？」 | Scores summarising skill |
| 5:30–6:00 | Signpost plan, safety-net, close | 「我建議幫你驗吓血，如果發現嚴重問題會即刻處理。如果期間有頭痛得好勁、流血止唔到，要即刻去急症。」 | Demonstrates safe management and safety-netting |
Uncovering the hidden agenda: The patient may worry about leukaemia/cancer, or fear their child is being abused (paediatric case), or be concerned about a new medication causing bruising. Always ask 「你最擔心呢啲瘀斑係咩嘢？」 early in ICE.
| Domain | English Question | Cantonese Question | Why It Matters | If Positive Think Of |
|---|---|---|---|---|
| Onset & duration | When did the purpura start? Sudden or gradual? | 「呢啲瘀斑幾時開始？係突然間出嘅定慢慢嚟？」 | Acute → ITP, HSP, DIC; chronic → CLD, drug | ITP, HSP, leukaemia |
| Distribution | Where are the lesions? Legs, buttocks, arms? | 「主要喺邊度出？腳？pat pat？手？」 | LL + buttocks → HSP; dependent areas → ITP; forearms → senile purpura | HSP, senile purpura |
| Palpability | Can you feel the spots are raised? | 「啲紅點摸落去凸唔凸起？」 | Palpable purpura → vasculitis [1]; flat → thrombocytopenia | HSP, ANCA vasculitis, cryoglobulinaemia |
| Blanching | Do the spots disappear when pressed? | 「你用手㩒住佢會唔會褪色？」 | Non-blanchable = purpura; blanchable = not purpura | Confirms true purpura |
| Mucosal bleeding | Any nosebleeds, gum bleeding, blood in urine/stool? | 「有冇流鼻血、牙肉出血、血尿或者大便有血？」 | Mucosal (wet) purpura predicts more serious bleeding [2] | ITP, DIC, leukaemia |
| Joint pain | Any joint pain or swelling? | 「有冇關節痛或者腫？」 | Arthralgia → HSP, SLE, vasculitis | HSP, SLE |
| Abdominal pain | Any tummy pain, vomiting, bloody stool? | 「有冇肚痛、嘔、屙血？」 | HSP GI involvement; intussusception in children [3] | HSP |
| Fever / recent URTI | Any fever or cold recently? | 「近排有冇發燒、傷風感冒？」 | 50% HSP preceded by URTI [3]; post-viral ITP | HSP, ITP |
| Haematuria | Any blood or dark colour in urine? | 「小便有冇血或者好深色？」 | HSP nephritis, SLE nephritis | HSP, SLE, vasculitis |
| Neuro symptoms | Any bad headache, confusion, weakness? | 「有冇好勁頭痛、意識模糊、手腳冇力？」 | ICH in severe thrombocytopenia; TTP pentad | TTP, ICH, meningococcal |
| Weight loss / fatigue | Lost weight? Feeling very tired? | 「有冇瘦咗？覺唔覺得好攰？」 | B symptoms → haematological malignancy | Leukaemia, lymphoma |
| Drug Hx | Taking aspirin, warfarin, NSAIDs, steroids, any new meds? | 「有冇食緊阿士匹靈、薄血丸、止痛藥、或者最近食咗啲新藥？」 | Drug-induced thrombocytopenia / drug-induced bleeding tendency [1][4] | DITP, anticoagulant effect |
| Alcohol | How much alcohol? | 「你飲幾多酒？」 | CLD → coagulopathy + thrombocytopenia (hypersplenism) [5] | Cirrhosis |
| PMHx | Any liver disease, kidney disease, autoimmune disease, cancer? | 「有冇肝病、腎病、免疫病、癌症？」 | Secondary causes of purpura | CLD, SLE, CLL, HIV |
| Family Hx | Family history of bleeding problems? | 「屋企人有冇出血嘅問題？」 | Inherited: vWD, haemophilia | vWD, haemophilia |
| Paediatric: trauma pattern | (If child) Any history of injury? Who looks after the child? | 「小朋友有冇跌親撞親？邊個湊佢？」 | Non-accidental injury (child abuse) [6] | Child abuse |
Case Report Form Answer Builder
"Purpura / easy bruising for [duration]"
High-yield points to capture:
- Onset, duration, progression
- Distribution (LL, buttocks, generalised, forearm)
- Palpable vs flat
- Associated: mucosal bleeding (epistaxis, gum bleeding, haematuria), joint pain, abdo pain, fever, recent URTI
- Drug history, alcohol, PMHx of liver/autoimmune/haem disease
- Relevant negatives: no headache, no confusion, no weight loss
| Likely RFC Examples | How to Phrase |
|---|---|
| Worried about unexplained bruising | "Patient noticed non-blanchable purple spots on lower limbs for 2 weeks and is concerned about the cause" |
| Child brought by parent worried about bruising | "Mother concerned about multiple bruises on child's legs and buttocks" |
| GP referral for low platelet count | "Referred for investigation of thrombocytopenia found on routine blood test" |
Tip: The RFC is NOT the diagnosis. It is the patient's reason for seeking care today. Always include the trigger.
| Component | Example Wording |
|---|---|
| Idea | "Patient thinks the bruises may be due to a blood disorder / low platelets" |
| Concern | "Patient is worried about leukaemia / cancer" or "Parent worried about a serious blood disease" |
| Expectation | "Patient hopes to have blood tests done and find out the cause; wants reassurance if nothing serious" |
For a typical FM station stem (otherwise well patient + purpura + isolated ↓PLT):
Immune thrombocytopenia (ITP) [2]
Minimum supporting evidence:
- Isolated thrombocytopenia (no anaemia, no leukopenia)
- Petechiae/purpura (mucocutaneous bleeding pattern)
- No hepatosplenomegaly
- No other apparent cause (diagnosis of exclusion)
If the stem features a child with palpable purpura on LL/buttocks + arthralgia ± abdo pain ± haematuria:
Henoch-Schönlein purpura (HSP / IgA vasculitis) [3]
Supporting: normal platelet count, palpable purpura over LL/buttocks, preceded by URTI
| DDx | Key Discriminator |
|---|---|
| HSP (IgA vasculitis) (or ITP if HSP is main Dx) | Palpable purpura, normal PLT, LL/buttocks, joint/abdo pain, haematuria |
| Drug-induced thrombocytopenia | Temporal association with new drug (e.g. heparin, quinine, sulfonamide) |
| Acute leukaemia | Pancytopenia (anaemia + neutropenia + thrombocytopenia), fatigue, hepatosplenomegaly, blasts on smear |
| Domain | Problem |
|---|---|
| Biological | Risk of serious bleeding (e.g. intracranial haemorrhage) if severe thrombocytopenia |
| Psychological | Anxiety about cancer/leukaemia; body image concern due to visible purpura |
| Social | Functional limitation (avoiding physical activity/work due to fear of bruising); if child – safeguarding concern |
| Diagnosis / DDx | Best Supporting Physical Sign | How to Elicit It | Why It Supports This Diagnosis |
|---|---|---|---|
| ITP | Petechiae / purpura on dependent areas (LL) with NO hepatosplenomegaly | Inspect lower limbs, palpate abdomen for liver/spleen | ITP = isolated ↓PLT; absence of organomegaly argues against leukaemia/CLD [2] |
| HSP | Palpable (raised) non-blanchable purpura on LL and buttocks | Palpate purpuric lesions – feel for raised edge; press with glass slide (diascopy) – does not blanch [3] | Palpable purpura = vasculitis; distribution in gravity/pressure-dependent areas is classic HSP |
| Acute leukaemia | Hepatosplenomegaly + pallor + lymphadenopathy | Palpate abdomen (spleen from RIF), check conjunctivae for pallor, palpate cervical/axillary LN | Organomegaly + pancytopenia = haematological malignancy until proven otherwise |
| Meningococcaemia | Non-blanching purpura fulminans + haemodynamic instability (↑HR, ↓BP, fever) | Vital signs + skin inspection for rapidly spreading purpura | Acutely unwell + spreading purpura = medical emergency |
| CLD | Stigmata of chronic liver disease (spider naevi, jaundice, palmar erythema, ascites) | Inspect face/chest for spider naevi, hands for palmar erythema, abdomen for ascites | Coagulopathy + hypersplenism → purpura in CLD context [5] |
| Senile purpura | Ecchymoses on dorsal forearms/hands, thin atrophic skin, no ↓PLT | Inspect forearms, note paper-thin skin | No reliable PE sign beyond characteristic appearance; normal bloods confirm |
Must Not Miss Red Flags
- Acutely unwell + purpura → meningococcaemia / DIC → urgent referral / A&E
- Purpura + headache + confusion → intracranial bleed or TTP → urgent referral
- Pancytopenia (anaemia + neutropenia + thrombocytopenia) → leukaemia / aplastic anaemia → urgent haem referral
- Wet purpura (mucosal bleeding: continuous epistaxis, oral blood blisters) → predicts more serious haemorrhage [2]
- Child with bruises in unusual sites (trunk, face, buttocks pattern inconsistent with play) → consider non-accidental injury [6]
Top traps that lose marks:
| Trap | How to Avoid |
|---|---|
| Confusing platelet-type bleeding with coagulation-type bleeding | Petechiae and purpura = platelet disorder; haemarthrosis and deep muscle bleeds = coagulation disorder [1] |
| Forgetting to ask about drugs | Always ask aspirin, warfarin, DOAC, heparin, chemotherapy, herbal meds |
| Calling HSP "thrombocytopenic" | HSP has NORMAL platelets – it is a vasculitis, not a platelet disorder [3] |
| Missing the hidden agenda (cancer fear / child abuse) | Explicitly ask ICE every time |
| Not examining for splenomegaly | Splenomegaly shifts the differential to leukaemia, CLD, hypersplenism |
| Forgetting fundoscopy mention | Fundoscopic exam for retinal haemorrhage is mentioned in GC slides as part of CNS bleeding assessment [1] |
Shortest safe management / safety-net line:
「我會安排驗血（包括血全圖、凝血功能），如果結果有問題會盡快聯絡你。期間如果有好勁嘅頭痛、流血止唔到、或者覺得好唔舒服，一定要即刻去急症室。」
Key GC lecture-slide points (highest yield):
- Petechiae ( < 2 mm), Purpura (2–10 mm), Ecchymosis ( > 1 cm) – subcutaneous bleeding pattern of platelet disorders [1]
- Platelet disorders → petechiae, purpura, mucosal bleeding; Coagulation disorders → ecchymosis, intra-articular/intramuscular bleeding [1]
- Isolated thrombocytopenia workup: repeat/confirm → isolated vs pancytopenia → if isolated, consider ITP, CLD, drug-induced → assess bleeding risk (fundoscopy for CNS bleeding) → treat [1]
- HSP: palpable purpura over LL and buttocks + arthralgia + abdo pain + renal disease; normal PLT and coagulation [3]
- Vasculitis causing palpable purpura in children is most common with Henoch-Schönlein purpura [7]
High Yield Summary
What to ASK: Onset/distribution/palpability of purpura; mucosal bleeding; joint pain; abdo pain; haematuria; fever/URTI; drug Hx; alcohol; family Hx bleeding; ICE (cancer fear?).
What to WRITE on CRF:
- CC: "Purpura on lower limbs for X weeks"
- Main Dx: ITP (isolated ↓PLT, no other cause) OR HSP (palpable purpura, normal PLT, classic tetrad)
- DDx: HSP / ITP / drug-induced thrombocytopenia / acute leukaemia
- Physical sign: Palpable purpura on LL/buttocks (HSP) or petechiae on dependent areas with no organomegaly (ITP)
- Biopsychosocial: bleeding risk / cancer anxiety / activity restriction or safeguarding
What NOT to MISS: Meningococcaemia (acutely unwell), leukaemia (pancytopenia), TTP (pentad), child abuse (unusual bruise pattern), drugs causing thrombocytopenia.
Active Recall - Family Medicine Clinical Test
[1] Lecture slides: GC 027. Abnormal bleeding after tooth extraction.pdf (p20, p24) [2] Senior notes: MBBS Final MB (Medicine) (Felix PY Lai).pdf (p1369 – ITP clinical manifestations and diagnosis) [3] Senior notes: MBBS Final MB (Pediatrics) (Felix PY Lai).pdf (p700–702 – HSP clinical features and diagnosis); Adrian Lui Pediatrics Notes.pdf (p460 – HSP) [4] Senior notes: Maksim Medicine Notes.pdf (p165 – DIC) [5] Senior notes: Ryan Ho GI.pdf (p312 – Cirrhosis stigmata and coagulopathy) [6] Lecture slides: GC 143. A child with multiple bruises_child abuse.pdf [7] Lecture slides: Taylor's Differential Diagnosis Manual 3ed.pdf (p362–363 – Petechiae and Purpura chapter)
Pruritus Ani
Pruritus ani is a dermatologic condition characterized by intense itching of the perianal skin, often caused by local irritants, infections, dermatologic disorders, or systemic conditions.
RLQ Pain
Right lower quadrant pain is abdominal pain localized to the area below and to the right of the umbilicus, most commonly associated with appendicitis but also with gynecologic, urologic, and bowel-related pathology.