Proliferative glomerulonephritis with monoclonal IgG deposits in a young female: a rare case misdiagnosed and immunosuppressive-treated for over four years

Abstract

BACKGROUNDProliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a newly recognized rare disease. The renal pathology is characterized by prominent manifestations of membranous hyperplasia, which is easy to misdiagnose. Clinical symptoms are severe. Massive proteinuria and hypoproteinemia are conspicuous, and most patients have renal insufficiency and microscopic hematuria.CASE PRESENTATIONA 27-year-old female was admitted to a hospital for macroscopic hematuria and proteinuria 4 years prior, and renal biopsy in the hospital suggested moderate-to-severe mesangial proliferating glomerulonephritis (MsPGN). She had taken glucocorticoid, cyclophosphamide (CTX), mycophenolate mofetil (MMF) and other treatments, and achieved brief partial remission. Recently, she visited our hospital due to massive proteinuria. Repeated renal biopsy and anatomic slice re-evaluation 4 years previous revealed monoclonal immunoglobulin deposition in the glomerulus. Bone marrow examination was performed to exclude hematologic malignancy, and the diagnosis was PGNMID. The patient showed remission after 4 cycles of bortezomib (B) + cyclophosphamide (C) + dexamethasone scheme (D).CONCLUSIONPGNMID is usually misdiagnosed as MsPGN or membranoproliferative glomerulonephritis (MPGN). Although it often occurs in middle-aged and elderly individuals, it cannot be readily excluded in young people, even when serum immunofixation electrophoresis (IFE) is negative. IgG subtype and light chain staining are necessary in the presence of high suspicion of this disease. An accurate diagnosis at the earliest stage may avoid overuse of glucocorticoids and immunosuppressants.