The current diagnostic criteria for IgA vasculitis are those established by EULAR/PRINTO/PRES, which state that in a pediatric patient with purpura (round, oval, or retiform) predominantly on the lower extremities, the diagnosis is confirmed if at least one of the following four criteria is present: (1) abdominal pain, (2) histological evidence of IgA deposition, (3) arthritis or arthralgia, or (4) renal involvement. Here, CD79A is linked to purpura.