You get called to a consult in the ED because there is a nine year-old Latino male who has a red raised rash on his legs and buttocks. When you see him, you also notice that his knee is swollen, but he seems to be walking without difficulty. Otherwise he looks happy and well. His CBC, ESR, and coagulation studies are normal.

What are the distinguishing histologic features of this vasculitis?

Henoch-Schonlein purpura (HSP) is a small vessel vasculitis; indeed, it can be thought of as a capillaritis. On histology, its characteristic features are leukocytoclasis (vascular damage caused by nuclear debris from infiltrating neutrophils) and IgA deposition. For this reason, it is also known as IgA-mediated vasculitis.

What are the major clinical manifestations of HSP?

HSP can be thought of as a clinical tetrad with (1) purpura: usually on the dependent (typically lower extremities) areas. The rash can also look petechial, vesicular, or bullous; (2) arthritis, often painless and accompanied by prominent periarticular swelling; 3) GI involvement, which can range from mild abdominal pain to hematochezia to intussusception to necrosis and perforation; 4) renal involvement, which can range from microscopic hematuria to nephrotic syndrome to acute or chronic renal failure.

What is the treatment of HSP?

HSP treatment is generally supportive with NSAIDs for pain if no GI or renal contraindications. The time-course is typically one to two months with about a one third of patients having recurrences after this period. The role of steroids is controversial. While they provide short-term relief of symptoms, it is unclear whether they alter the long-term outcome, specifically renal, of the disease.