CD79A and purpura: Immunoglobulin A-associated vasculitis (IgAV; formerly known as Henoch-Schönlein purpura) is a leucocytoclastic, immune complex-mediated, small vessel vasculitis characterized clinically by palpable purpura, joint, gastrointestinal, or renal involvement and histologically by the predominance of IgA deposits in the vascular wall.