IgAvasculitis

IgA vasculitis, also known as IgA vasculitis or Henoch-Schönlein purpura (HSP) when presenting with classic features, is a small‑vessel vasculitis driven by immune complex deposition of IgA in the walls of small vessels. It most often affects children but can occur in adults. The condition typically follows an upper respiratory infection or other antigenic trigger, though in many cases no trigger is identified.

The hallmark clinical feature is palpable purpura, usually on the legs and buttocks, reflecting small-vessel inflammation. Many patients also experience arthralgia or arthritis, particularly of the knees and ankles, and abdominal pain that can be colicky and may be accompanied by nausea, vomiting, or GI bleeding. Renal involvement occurs in a subset of patients and can range from mild hematuria to nephritic or nephrotic syndrome; kidney disease is a key determinant of prognosis, especially in adults.

Diagnosis is mainly clinical, supported by laboratory tests and, if needed, a skin or kidney biopsy. Immunofluorescence of a skin biopsy typically shows IgA deposition in small vessels. Urinalysis and kidney function tests monitor for renal involvement; blood counts and inflammatory markers may be abnormal during active disease.

Treatment is usually supportive and tailored to symptom severity. Most children recover within weeks to months without long-term consequences. For severe abdominal pain, persistent edema, or significant joint symptoms, nonsteroidal anti-inflammatory drugs or corticosteroids may be used; renal involvement may require nephrology input and, in rare cases, immunosuppressive therapy.

Prognosis is generally favorable in children, with a minority experiencing persistent or recurrent kidney disease. Adults have a higher risk of renal complications and longer recovery.