Electron-dense subepithelial glomerular deposits in Henoch-Schönlein purpura syndrome.

A case of Henoch-Schönlein purpura (HSP) with renal lesions is presented. The clinical, laboratory, and morphologic findings revealed features commonly described in HSP. A renal biopsy revealed diffuse, generalized, proliferative glomerulonephritis. The unusual findings in this case were numerous electron-dense subepithelial deposits ("humps") and a few small intramembranous deposits in the glomerular capillaries without deposits in the mesangium, mimicking those of acute poststreptococcal glomerulonephritis. The electron-dense deposits were well correlated with deposits of IgG, IgA, C3, C4, C1q, and fibrin-fibrinogen demonstrated by immunofluorescent microscopy.