CD79A and Henoch-Schoenlein purpura: Henoch-Schönlein purpura (HSP), or immunoglobulin A (IgA) vasculitis (IgAV), is a small vessel vasculitis that is most commonly seen in children; it is classically characterized by IgA deposition within the renal mesangium, resulting in a wide range of symptoms: palpable purpura, arthralgia, gastrointestinal symptoms, renal involvement, and, in severe cases, pulmonary complications or intussusception.