– vessel wall deposition of complement C3 occurs in two‐thirds of the cases;
– Deposition of Immunoglobulin M, immunoglobulin A (≈30%), immunoglobulin G or immunoglobulin E is less common.
Contrary to Henoch-Schönlein vasculitis, deposition of immunoglobulin A occurs exclusively in a minority of cases.
Acute hemorrhagic edema of young children is a distinctive immune‐mediated vasculitis (contrary to pauci‐immune vasculitides such as microscopic polyangiitis, granulomatosis with polyangiitis, and eosinophilic granulomatosis with polyangiitis).
