CD79A and purpura: Besides a mandatory criterion such as palpable purpura (not thrombocytopenia), the latest diagnostic criteria of HSP include at least 1 of the following manifestations: diffuse abdominal pain, leukocytoclastic vasculitis with predominant IgA deposits on skin biopsy, acute arthritis, or arthralgias in any joint, and renal involvement as evidenced by proteinuria and/or hematuria.[2]