Mesangial proliferative glomerulonephritis with unusual intramembranous granular dense deposits.

We have studied two patients with histories of upper respiratory tract infection. Hematuria and proteinuria were the presenting renal symptoms in one patients and an acute nephritic syndrome in the other. Serological findings disclosed depression of total hemolytic complement activity with low levels of C3 and the presence of C3Nef activity. Light microscopy showed diffuse mesangial cell proliferation. By immunofluorescence, diffuse deposits of C3 were found in the glomeruli. Ultrastructural studies revealed segmental thickening of the glomerular basement membrane due to the deposition of granular electron-dense deposits in a laminar pattern. We suggest that our cases may represent a variant of hypocomplementemic glomerulonephritis or perhaps the early stages of dense deposit disease.