Hypocomplementemic urticarial vasculitis: report of a pediatric case.

Hypocomplementemic urticarial vasculitis syndrome (HUVS) is well described in adults but is quite rare in children. We report a pediatric case of HUVS initially diagnosed as juvenile rheumatoid arthritis and then as Henoch-Schönlein purpura. Beginning at 3 years of age, our patient developed polyarthritis with hypocomplementemia. She subsequently experienced an intermittent purpuric rash beginning at age 4 years, and she continued to have episodic arthritis and rash for years. Hematuria and proteinuria were noted at 12 years of age; renal biopsy revealed membranoproliferative glomerulonephritis with membranous features. Serum complement evaluation revealed activation of the classical pathway, consistent with HUVS. Therapy with oral dapsone led to improvement in proteinuria. HUVS should be considered in the differential diagnosis of pediatric patients with glomerulonephritis, urticarial rash, arthritis/arthralgias, and obstructive pulmonary disease.