Suspect the unexpected: proliferative glomerulonephritis with monoclonal immunoglobulin deposits and a negative hematological work-up. A case of monoclonal gammopathy of renal significance

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is a subtype of monoclonal gammopathy of renal significance (MGRS). PGNMID can present with insidious, slowly progressing kidney damage to overt nephrotic syndrome or rapidly progressive glomerulonephritis. It is a renal-limited disease that often lacks a detectable plasma or B-cell clone and requires kidney biopsy for diagnosis. We present the case of a 77-year-old woman who developed nephrotic range proteinuria and progressive chronic kidney disease, despite a normal hematological work-up that showed no evidence of monoclonality. This case highlights the potential risk for severe renal damage caused by monoclonal proteins, even in the absence of a detectable pathological hematologic clone. PGNMID requires further research to gain knowledge regarding pathophysiology and potential serum biomarkers for diagnosis as well as therapy response.