Dense deposit disease in a child with febrile sore throat.

Dense deposit disease or membranoproliferative glomerulonephritis type II is a rare glomerulopathy characterized on renal biopsy by deposition of abnormal electron-dense material in the glomerular basement membrane. The pathophysiologic basis is uncontrolled systemic activation of the alternate pathway of the complement cascade. C3 nephritic factor, an autoantibody directed against the C3 convertase of the alternate pathway, plays a key role. In some patients, complement gene mutations have been identified. We report the case of a child who had persistent microscopic hematuria, proteinuria, and hypocomplementemia C3 for over 2 months. Renal biopsy confirmed the diagnosis of dense deposit disease.