Membranous nephropathy as a segmental pattern with solitary immunoglobulin A deposition: a case report.

A 67-year-old man with a history of hypertension and dyslipidemia presented with edema and heavy proteinuria. Light microscopic analysis of kidney biopsy revealed a diffuse segmental membranous feature. Immunofluorescence stain was segmentally positive for IgA, galactose-deficient IgA1, both κ and λ light chains, and C3 along the glomerular capillary walls, but negative for IgG, IgM, or C1q. Electron microscopy showed subepithelial and intramembranous electron-dense deposits (EDD) in the segmental glomerular capillary walls, along with foot process effacement in the corresponding areas. No EDD was observed in the mesangial or para-mesangial areas. The patient's histopathology revealed membranous nephropathy with a solitary IgA deposition. No clinical findings suggested a secondary cause of membranous nephropathy. Combination therapy with corticosteroids and cyclosporine resulted in proteinuria remission. To our knowledge, this is the first reported case of membranous nephropathy with a segmental pattern associated with solitary IgA and galactose-deficient IgA1 deposition. Further case reports and studies are required to elucidate the pathogenesis of membranous nephropathy, which shows these unique histopathological features.