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

Abstract

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.

Keywords: Kidney biopsy; Nephrotic syndrome; Segmental membranous nephropathy; Solitary IgA deposition.

Fig. 1

A Light microscopy findings from kidney biopsy samples. Periodic acid methenamine silver (PAM) stain (× 400 original magnification). B The glomeruli showed segmental capillary walls thickening with spike formation (arrowheads). PAM stain (× 600 original magnification). C, D Immunohistochemical staining for IgA (C) and C3 (D) showing diffuse segmental granular staining along the glomerular capillary walls (× 400 original magnification). E–H Immunofluorescent staining for IgA (E), KM55 (F), κ-light chain (G), λ-light chain (H). Segmental and granular staining of IgA, KM55, and κ- and λ-light chains along the segmental glomerular capillary walls (× 400, original magnification)

Fig. 2

(A, B) Electron microscopy findings showing electron-dense deposits in the subepithelial and intramembranous areas (yellow arrowheads), irregular thickening of the glomerular basement membrane (green arrowheads), and dissolution of deposits (red arrowheads) (× 1200 original magnification, bar = 2.5 μm)

Fig. 3

Clinical course of the present case. Alb albumin, Cr creatinine, CyA: cyclosporine A, PSL prednisolone