ANCA-associated and other childhood vasculitides — branching viva

Emergency department: a 14-year-old boy with three weeks of bloody nasal discharge, a septal ulcer, a productive cough, and cola-coloured urine, a rising creatinine, and a positive PR3 (c-ANCA). The examiner asks: name the diagnosis and classify the vasculitides by vessel size, then branches to the pauci-immune mechanism and the remission-induction and maintenance framework, to the same boy re-presenting with an absent radial pulse and hypertension that opens the Takayasu arteritis pathway, to the asthma and eosinophilia and mononeuritis multiplex that opens the eosinophilic granulomatosis with polyangiitis and its cardiac danger, and finally to the Kawasaki cross-link of the medium-vessel, ANCA-negative disease treated with intravenous immunoglobulin and aspirin.