In medicine (rheumatology and pediatrics) Henoch-Schönlein purpura (HSP, also known as allergic purpura) is a form of vasculitis that mainly affects children. Its course is generally benign, although some serious complications can develop, mainly of the kidney and intestine
The purpura that are mentioned in the name of the disease are present in all patients. They are located on the legs and arms, and progress to the trunk. As purpura are small haemorrhages, they are non-blanching (i.e. they do not disappear on pressure), which can lead to confusion with the petechiae of meningococcal sepsis. Often, the symptoms are preceded by a viral upper respiratory tract infection.