Figure 87-1 Rash of Henoch-Schönlein purpura on the lower extremities of a child. Note evidence of both purpura and petechiae.
Erythrocyte sedimentation rate, C-reactive protein, and white blood cell count are elevated in patients with HSP. The platelet count is the most important test, because HSP is characterized by nonthrombocytopenic purpura with a normal, or even high, platelet count, differentiating HSP from other causes of purpura that are associated with thrombocytopenia such as autoimmune thrombocytopenia, systemic lupus erythematosus, or leukemia. A urinalysis screens for evidence of hematuria. A serum blood urea nitrogen and creatinine should be obtained to evaluate renal function. Testing the stool for blood may identify evidence of gut ischemia. Any question of gut perforation requires radiologic investigation.
The diagnosis of HSP is based on the presence of two of four criteria (Table 87-1), which provides 87.1% sensitivity and 87.7% specificity for the disease. The differential diagnosis includes other systemic vasculitides (Table 87-2) and diseases associated with thrombocytopenic purpura, such as idiopathic thrombocytopenic purpura and leukemia.
Therapy for HSP is supportive. A short-term course of non-steroidal anti-inflammatory drugs can be administered for the acute arthritis. Systemic corticosteroids usually are reserved for children with gastrointestinal disease and provide significant relief of abdominal pain. A typical dosing regimen is prednisone, 1 mg/kg/day for 1 to 2 weeks, followed by a taper schedule. Recurrence of abdominal pain as corticosteroids are weaned may necessitate a longer course of treatment. Acute nephritis typically is treated with corticosteroids but may require more aggressive immunosuppressive therapy.
Most cases of HSP are monophasic, lasting 3 to 4 weeks andresolving completely. The rash can wax and wane, however, for1 year after HSP. Parents should be warned regarding possiblerecurrences. The arthritis of HSP does not leave any permanent joint damage; it does not typically recur. Gastrointestinalinvolvement can lead to temporary abnormal peristalsis thatposes a risk of intussusception, which may be followed by complete obstruction or infarction with bowel perforation. Any child
Palpable purpura Raised, palpable hemorrhagic skin lesions in the absence of thrombocytopenia
Bowel angina Diffuse abdominal pain or the diagnosis of bowel ischemia
Diagnostic biopsy Histologic changes showing granulocytes in the walls of arterioles or venules; IgA deposits in vessel wall
Pediatric age group Age <20 years at onset of symptoms *The diagnosis of Henoch-Schönlein purpura is based on the presence of two of four criteria.
Granulomatosis with polyangiitis (formerly known as Wegener granulomatosis) Polyarteritis nodosa Churg-Strauss syndrome Microscopic polyangiitis
Henoch-Schönlein purpura Serum sickness (e.g., drug-related) Vasculitis associated with infections with a recent history of HSP who presents with acute abdominalpain, obstipation, or diarrhea should be evaluated for intussusception. Renal involvement rarely may lead to renal failure.