Schönlein-Henoch purpura (SHP) is a systemic IgA vasculitis that affects small vessels. It is characterized by skin purpura, arthritis, and abdominal and/or renal involvement. SHP usually affects children and is rare in adults. Annual incidence in children is estimated at between 1/6,660 and 1/4,880, whereas it is estimated at around 1/1,000,000 in adults. The male-to-female ratio is 1.5:1. Patients present with vascular purpura that is usually symmetrical and primarily localized to the buttocks and legs. In adults it is more frequently complicated by necrotic or hemorrhagic bullous lesions. The lesions progressively regress, disappear after a few days and, in 80% of cases, never reappear. Patients also present with arthralgia, predominantly involving the knees and ankles. Abdominal pain is common and may be associated with life-threatening gastrointestinal bleeding. Renal involvement is more severe and frequent in adults. It usually consists of microscopic hematuria with varying degrees of proteinuria. Nephrotic syndrome, renal failure, and hypertension may also occur. Other manifestations are rare but may include headaches, seizures, paresis, orchiepididymitis, uretritis, pancreatitis, myositis, episcleritis, pulmonary bleeding and myocarditis. SHP is associated with deposition of IgA-dominant immune complexes in arterioles, capillaries, and venules, but the exact etiology remains unknown. Several different bacterial organisms, drugs, foods, and insect bites have been implicated as the initiating factors of the disease. The diagnosis is based on clinical and histopathological findings. Examination of skin and kidney biopsies reveals tissue deposition of IgA with circulating IgA immune complexes. Differential diagnoses include other causes of purpura such as thrombopenia, hemopathy or infectious diseases. In adults, Wegener granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, systemic lupus erythematosus, and mixed cryoglobulinemia (see these terms) should also be considered in the differential diagnosis. The treatment is symptomatic. The use of steroids and/or immunosuppressors is controversial but may be considered in case of severe gastrointestinal or renal manifestations. Gastrointestinal or pulmonary bleeding can be life-threatening. The long term prognosis depends on the extent of the renal involvement. Long term follow-up studies of adult series show that end-stage renal failure may occur in up to one-third of patients.
Last update: March 2009