Henoch-Schonlein purpura is a disease that involves purple spots on the skin, joint pain, gastrointestinal problems, and
Anaphylactoid purpura; Vascular purpura
Causes, incidence, and risk factors
Henoch-Schonlein is caused by an abnormal response of the immune system. It is unclear why this occurs.
The syndrome is usually seen in children, but it may affect people of any age. It is more common in boys than in girls. Many people with Henoch-Schonlein purpura had an upper respiratory illness in the weeks before.