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

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.