Henoch-Schonlein is caused by an abnormal response of the immune system. It is unclear why this occurs.
The syndrome is mostly seen in children, but it may affect people of any age. It is more common in boys than in girls. Many people who develop this disease had an upper respiratory infection in the weeks before.
Ardoin SP, Fels E. Vasculitis syndromes. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 161.
Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.