Henoch-Schonlein purpura (HSP) is a systemic, generalized vasculitis o
f unknown etiology thought to be related to an IgA-mediated autoimmune
phenomenon. Diagnosis is based on a constellation of physical finding
s that include the characteristic nonthrombocytopenic petechial or pur
puric rash, migratory polyarthralgias, abdominal pain, and renal compl
ications. We report the case of a 19-year-old man with a diagnosis of
HSP who had severe abdominal pain and endoscopic documentation of duod
enal involvement. Though not clear at presentation, the diagnosis beca
me obvious when the characteristic rash emerged.