Non-Randall proliferative glomerulonephritis with humps and monotypic IgG deposits in primary Sjögren's syndrome: a first case report

Abstract

Renal involvement is frequent in patients suffering from primary Sjögren's syndrome (pSS). Tubulointerstitial infiltration is the most common renal lesion, while glomerular involvement is rare. We report the case of a 50-year-old woman with pSS who developed renal failure due to an unusual proliferative glomerulonephritis with humps and monotypic IgG1-kappa deposits. Searches for cryoglobulinaemia, anti-double-stranded DNA and anti-neutrophil cytoplasmic antibodies were negative. Serum protein electrophoresis and immunofixation revealed no monoclonal immunoglobulin. Extensive work-up excluded associated infectious, collagen or lymphoproliferative disease. This case adds to the spectrum of pSS-related glomerular disease which is reviewed in depth.

Keywords: Sjögren’s syndrome; crescentic glomerulonephritis; renal involvement.

Fig. 1

Light and electron microscopy. (A) Renal biopsy stained by Masson’s trichrome. (B) Detail of a glomerulus, showing red humps stained by Masson’s trichrome (arrows). (C) On this high-power field of a Jones’ stain-stained glomerulus, humps are easily demonstrated (arrows). In the inset, they look like pink eggs (immune deposits are eosinophilic) lying on black egg cups (spikes are stained by silver salts). There is a mild mesangial proliferation but no double contours. (D) Electron micrograph of two capillary walls, showing one hump (asterisk) flanked by spikes (arrows). The immune deposit is not organized. BM, basement membrane; U, urinary space; RBC, red blood cell.

Fig. 2

Immunofluorescence pictures show subepithelial deposits that are heavily positive for anti-gamma-1, anti-C3 and anti-kappa antibodies. No reactivity was seen with anti-lambda antibody.