C3 mesangial proliferative glomerulonephritis initially presenting with atypical hemolytic uremic syndrome: a case report.

Background: Hemolytic uremic syndrome is characterized by acute renal failure, thrombocytopenia, and Coombs-negative hemolytic anemia. In C3 mesangial proliferative glomerulonephritis, an increase in mesangial cell proliferation without thickening in the glomerular capillary wall can be seen under light microscopy, but the definitive diagnosis is made with the immunohistologic demonstration of isolated C3 deposits in the mesangium. C3 glomerulonephritis may be detected in childhood; however, in this case report we describe the first case of isolated C3 glomerulonephritis together with atypical hemolytic uremic syndrome in an adult patient.

Case Presentation: Here we present a case of a 27-year-old white man with anuria who was hospitalized after being diagnosed as having hemolytic uremic syndrome accompanied by acute renal failure. Renal biopsy results revealed C3 glomerulonephritis. There was a complete recovery of renal function after hemodialysis, and prednisolone and plasma exchange treatment.

Conclusions: C3 glomerulopathy is distinct from atypical hemolytic uremic syndrome although both diseases are due to abnormal control of the alternative complement pathway. In atypical hemolytic uremic syndrome activation of complement occurs on glomerular or microvascular endothelium causing a thrombotic microangiopathy; in most cases, no electron-dense deposits are seen on electron microscopy and glomerular C3 is not detected on immunofluorescence.