Henoch-Schonlein purpura is a small-vessel leukocytoclastic vasculitis associated with IgA subclass 1 deposition in vessel walls. It is most common in children and is often associated with an inciting infection, such as group A streptococcus or other exposure. There is a male predominance. It classically presents with palpable purpura in the lower extremities and buttock area; ahralgias; and abdominal symptoms, such as nausea, colic, and melena. A decrease in GFR is common with a nephritic presentation. The renal lesions are considered by most expes to be identical to those found in IgA nephropathy. Skin biopsy demonstrates leukocytoclastic vasculitis with IgA and C3 deposition. Ref: Watnick S., Dirkx T. (2013). Chapter 22. Kidney Disease. In M.A. Papadakis, S.J. McPhee, M.W. Rabow (Eds), CURRENT Medical Diagnosis & Treatment 2013.