IgA vasculitis — viva

Opening diagnosis

Examiner: What is the likely diagnosis in the stimulus?

Candidate: IgA vasculitis, formerly Henoch-Schönlein purpura. It is an IgA immune-complex small-vessel vasculitis. The stem gives the classic tetrad: palpable lower-limb or buttock purpura, ankle arthralgia or arthritis, colicky abdominal pain, and renal involvement with haematuria. The normal platelet count is important because it separates it from thrombocytopenic purpura.^[1]

Diagnostic criteria and pathology

Examiner: What clinical criteria support the diagnosis?

^[3]Candidate: The practical classification framework requires purpura or petechiae with lower-limb predominance and not due to thrombocytopenia, plus at least one of abdominal pain, arthritis or arthralgia, renal involvement, or histopathology showing IgA deposition. In a typical child it is usually a clinical diagnosis; atypical, severe, adult, or uncertain disease needs biopsy.^[4]

Examiner: What would skin biopsy show?

Candidate: Routine histology shows leukocytoclastic vasculitis: neutrophils around small dermal vessels, nuclear dust, fibrinoid necrosis, endothelial injury, oedema, and red-cell extravasation. Direct immunofluorescence from a fresh lesion shows IgA-dominant deposition in vessel walls, often with C3 or fibrin.^[2]

Differential diagnosis

Examiner: Give the important differentials and how you separate them.

Candidate: ITP gives petechiae and bruising with low platelets rather than palpable purpura with a normal platelet count. Meningococcaemia or purpura fulminans gives fever, toxicity, shock, rapidly progressive purpura, and DIC features and must be treated immediately. HUS gives microangiopathic haemolysis, thrombocytopenia, and acute kidney injury, often after bloody diarrhoea. ANCA vasculitis is more likely in older patients with lung, sinus, neuropathy, or rapidly progressive renal disease. SLE vasculitis has lupus features, cytopenias, low complement, ANA or anti-dsDNA, and broader systemic involvement.^[1][2]

Investigations

Examiner: What investigations do you order at first contact?

Candidate: FBC with platelet count, renal function and electrolytes, urinalysis, urine protein quantification if protein is positive, blood pressure, and stool occult blood if there are GI symptoms. I would add coagulation and sepsis tests if the child is ill or bleeding, abdominal ultrasound for severe abdominal pain or suspected intussusception, scrotal Doppler if torsion is possible, skin biopsy if diagnosis is uncertain, and renal biopsy through nephrology if there is significant nephritis.^[1][3]

Management

Examiner: How do you manage uncomplicated disease?

Candidate: Supportive care: explanation, rest during painful episodes, hydration, paracetamol, and avoidance of nephrotoxins. NSAIDs may help joint symptoms only if renal function, hydration, BP, and GI status are reassuring; I would avoid NSAIDs if there is renal involvement, dehydration, GI bleeding, or severe abdominal pain. I would document baseline urine, BP, renal function, and follow-up.^[1][4]

Examiner: When do steroids and nephrology become relevant?

Candidate: Corticosteroids are used for severe abdominal pain or significant joint symptoms after surgical emergencies have been considered, and for renal disease under specialist guidance. A common symptomatic regimen is prednisolone about 1 to 2 mg/kg/day with taper according to response. Steroids do not reliably prevent nephritis, so renal surveillance continues. Nephrology is needed for hypertension, rising creatinine, nephritic syndrome, nephrotic syndrome, rapidly progressive features, or persistent/significant proteinuria; ACE inhibitor or ARB therapy for persistent proteinuria is nephrology-guided.^[1][3][4]

Prognosis and follow-up

Examiner: What determines prognosis?

Candidate: In children, skin, joint, and abdominal symptoms usually resolve, though relapses occur. Long-term prognosis is determined mainly by renal involvement, especially persistent proteinuria, hypertension, impaired kidney function, nephritic syndrome, nephrotic syndrome, or severe biopsy findings. Adults have a worse renal prognosis than children and need a lower threshold for biopsy and specialist follow-up.^[2][3]

Examiner: What follow-up schedule would you state in an exam?

Candidate: Every patient needs urinalysis and blood pressure surveillance for at least six to twelve months, longer if any abnormality persists. If urine protein is present, quantify it. Persistent proteinuria, hypertension, reduced eGFR, macroscopic haematuria with renal impairment, nephritic syndrome, nephrotic syndrome, or rapidly progressive glomerulonephritis needs nephrology referral.^[3][4]