Fibrillary Glomerulonephritis with Atypical Immunoglobulin M Deposits and Hypocomplementemia Revealed Human Immunodeficiency Virus Infection.

Fibrillary glomerulonephritis (FGN) is a rare form of glomerulonephritis, and the incidence in native renal biopsies is less than 1%. The diagnosis of FGN is defined by the ultrastructural finding of organized, randomly oriented, nonbranching fibrils with a diameter of 10-30 nm. FGN is immune-mediated glomerulonephritis with predominant immunoglobulin (Ig) G deposits. Hypocomplementemia is very rare. We report the case of a 68-year-old Caucasian man with renal impairment, hematuria, subnephrotic proteinuria, hypocomplementemia (low C4, normal C3), and hypergammaglobulinemia. The kidney biopsy revealed a mesangial proliferative pattern with IgM deposits, and the electron microscopy demonstrated FGN. Upon further investigation, secondary causes, such as malignancy, monoclonal gammopathy, or autoimmune disease were excluded, and human immunodeficiency virus (HIV) infection was revealed. Only three cases with FGN associated with HIV infection without concurrent hepatitis C virus have been reported and all of them in already known medical records. Our patient received treatment with corticosteroids and highly active antiretroviral therapy, and the renal function improved.