Henoch-Schönlein purpura: an atypical cause of abdominal pain in a 70-year-old man: case report.

Henoch-Schönlein purpura (HSP) is a leukocytoclastic small-vessel vasculitis involving small vessels with the deposition of immune complexes containing immunoglobulin A and neutrophil and eosinophilic infiltration. Clinical manifestations include 4 classic signs and symptoms: skin lesions, arthralgias, abdominal pain, and renal disease. HSP primarily affects children and is uncommon in adults.