Henoch-Schönlein purpura (HSP) is the most common systemic vasculitis in children, with a peak incidence between ages 3 and 15 years and with 90% of patients younger than age 10. It is characterized by four main clinical manifestations. The classic exanthem of HSP begins with erythematous macules or urticaria that eventually coalesce and evolve into ecchymotic lesions and palpable purpura. The lesions are more often located on the buttocks and gravity-dependent areas (lower extremities) in ambulatory children. In nonambulatory children, the lesions can be seen on the face, trunk, and upper extremities as well. Mucosal involvement is rare; however, edema of the scalp, hands, scrotum, and periorbital tissue occurs.
Migratory oligoarticular (one to four joints) arthritis and arthralgia are eventually seen in 75% of patients. Gastrointestinal symptoms (colicky abdominal pain, occult or gross blood in the stool, and small bowel–small bowel intussusception) usually develop within a week of the rash, but may precede it. Renal involvement is the most frequent serious complication and usually occurs during the 1st month. It commonly manifests as microscopic hematuria and may progress to glomerulonephritis. One percent progress to end-stage renal disease. Hypertension is uncommon.
Diagnosis is made by history and clinical examination. Most laboratory tests are usually nonspecific except for the urinalysis, which may be positive for blood or protein in 50%. The overall prognosis is excellent, with full recovery in most. The course is marked by relapses and remissions in 50% (the rash tends to recur within the first 6 weeks). Prognosis is linked to renal involvement. The rash may be confused with drug reactions, erythema multiforme, urticaria, and even physical abuse. Consider other causes of purpura, such as bleeding disorders or infection (meningococcemia).
Management and Disposition
Treatment is supportive. Patients with HSP limited to the skin and joints with minimal renal involvement can be managed as outpatients. Hospitalization is warranted when patients cannot maintain oral intake; have severe abdominal pain, GI hemorrhage, and intussusception; are unable to ambulate or care for themselves because of significant joint pain; or have evidence of renal injury (renal failure, nephritis, nephrotic range proteinuria, or significant hypertension for age). Ibuprofen or naproxen can be effective for symptomatic pain relief, although providers should be cautious in patients with GI bleeding or glomerulonephritis. Corticosteroids may shorten the duration of abdominal pain in patients with severe symptoms who are unable to maintain oral intake or require admission to the hospital, but it will not prevent complications of HSP. In rare cases where ileocolic intussusception is diagnosed, air contrast enema and prompt surgical consultation are indicated. In contrast to ileocolic intussusception, small bowel–small bowel intussusception generally resolves spontaneously and rarely requires invasive intervention.
Obtain a stool occult blood test and urinalysis in patients with abdominal pain and suspected HSP. The fecal occult blood test is positive in more than half.