Henoch-Schonlein is a type of hypersensitivity vasculitis and inflammatory response within the blood vessel. It is caused by an abnormal response of the immune system. The exact cause for this disorder is unknown.
Update Date 4/20/2013
Updated by: 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.