On this page
Study tools
Write your answer
Saved on this device. No marking — you are the marker.
Stem
A 5-year-old boy is brought to the emergency department with a 2-day history of a palpable purpuric rash over his lower legs and buttocks, swollen tender knees and ankles, and intermittent colicky periumbilical abdominal pain. He had a sore throat and cough two weeks ago that resolved. On examination he is afebrile, alert, and well-perfused; blood pressure is at the 75th centile for age. There is symmetrical palpable non-blanching purpura on the lower limbs and buttocks, and tender periarticular swelling of both knees and ankles. The abdomen is soft with mild periumbilical tenderness, no guarding, no palpable mass. Bedside urinalysis shows blood 2+ and protein 1+. Full blood count: platelets 280 x10^9/L, haemoglobin 118 g/L, WCC 11.2 x10^9/L. Coagulation screen normal. Urea, electrolytes and creatinine normal. Albumin 32 g/L.
Questions
a) What is the most likely diagnosis and which classification criteria support it? (2 marks) Henoch-Schonlein purpura (HSP), also called IgA vasculitis — the most common vasculitis of childhood. The diagnosis is clinical. EULAR/PRINTO/PRES 2010 criteria: mandatory palpable purpura/petechiae with lower-limb predominance (present) PLUS at least one of diffuse abdominal pain, arthritis/arthralgia, renal involvement (haematuria/proteinuria), or IgA on biopsy. He has purpura + arthritis + abdominal pain + renal involvement — criteria satisfied. Platelets are normal, excluding ITP.
b) Explain, with the mechanism, why this child's purpura is palpable and why the platelet count is normal. (2 marks) HSP is a small-vessel leukocytoclastic vasculitis caused by deposition of galactose-deficient IgA1 immune complexes in dermal venules, activating the alternative and lectin complement pathways and recruiting neutrophils. This inflammatory infiltrate in the vessel wall makes the purpura palpable and causes extravasation of blood. The platelet count is normal because the bleeding is due to vessel-wall inflammation, not thrombocytopenia — in contrast to ITP, where isolated low platelets produce non-palpable purpura.
c) List four complications that must be actively excluded or monitored for in this child. (2 marks)
- Intussusception — classically ileo-ileal in HSP (unlike idiopathic ileo-colic); suspect if severe colicky pain, mass, red-currant-jelly stool; ultrasound; usually needs surgery (enema reduction often fails).
- HSP nephritis — already has haematuria/proteinuria; can progress to nephritic/nephrotic syndrome, hypertension, AKI, crescentic GN; may develop or worsen late.
- GI bleeding / protein-losing enteropathy — monitor for melaena, worsening hypoalbuminaemia.
- Testicular torsion (if scrotal pain/swelling develops) — urgent Doppler ultrasound; surgical exploration if not excluded.
d) Outline the stepwise management for this child. (2 marks) Step 1 — Supportive: rest, hydration, simple analgesia (paracetamol 10-15 mg/kg every 4-6 h). Step 2 — NSAIDs for arthritis (ibuprofen 5-10 mg/kg TDS) — acceptable here as renal function is normal; AVOID if renal involvement worsens. Step 3 — corticosteroids (oral prednisolone 1-2 mg/kg/day, max 60-80 mg) reserved for severe GI pain/bleeding, significant renal involvement, or severe systemic symptoms — NOT routinely, as they do NOT prevent nephritis (Jauhola 2011). Step 4 — immunosuppression (cyclophosphamide/MMF/calcineurin/rituximab) plus ACE inhibitor for ISKDC III-VI crescentic disease. Currently this child has mild disease → supportive + NSAIDs.
e) Describe the follow-up and monitoring plan after discharge and justify it. (2 marks) Because HSP nephritis can develop weeks to months after the rash resolves, he needs serial blood pressure (age/height centile) and urinalysis (dipstick for blood and protein): weekly during the active illness, then monthly for 6 months, then every 3-6 months up to 12 months (longer given he already has renal involvement). Escalate to nephrology and consider renal biopsy if heavy/new proteinuria, nephritic or nephrotic syndrome, hypertension, or rising creatinine. Counsel parents to return urgently for severe abdominal pain, swollen/painful scrotum, dark urine, reduced urine output, or persistent fever.