Hydralazine use can be associated with IgM-dominated immune complex-mediated glomerulonephritis.

IgM-dominant immune complex-mediated glomerulonephritis (IgM-dominant ICMGN) is a rare renal entity, characterized by a membranoproliferative pattern by light microscopy, dominant IgM staining by immunofluorescent staining, and subendothelial deposits by electron microscopy. This study was to investigate if some of IgM-ICMGN were associated with autoimmune disorders induced by hydralazine. Seven IgM-dominant ICMGN cases were identified over 8 years. Their pathologic phenotypes and clinical scenarios were analyzed in detail. Patients' ages ranged from 47 to 87 years old with 5 women and two men. Six of seven patients had drug-induced autoimmune phenomenon (hydralazine-induced positive ANCA and ANA). All of them had renal dysfunction and some proteinuria. Most pathologic features showed a membranoproliferative pattern of glomerulonephritis with dominant IgM deposits at subendothelial spaces. IgM nephropathy (a variant of focal segmental glomerulosclerosis), chronic thrombotic microangiopathy, and cryoglobulinemic glomerulopathy were ruled out in the cases. The hydralazine-induced autoimmune phenomenon can be seen in IgM-dominant ICMGN, which should be classified as a subtype of membranoproliferative glomerulonephritis.