Proliferative glomerulonephritis with monoclonal immunoglobulin G deposits in a young woman: A case report

Abstract

BACKGROUND Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a newly recognized rare disease. The renal pathology is characterized by prominent manifestations of membranous hyperplasia, which are easy to misdiagnose. The clinical symptoms are severe. Massive proteinuria and hypoproteinemia are conspicuous, and most patients are accompanied by renal insufficiency and microscopic hematuria. CASE SUMMARY A 27-year-old woman 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 a glucocorticoid, cyclophosphamide, mycophenolate mofetil, and other treatments and achieved brief partial remission. Recently, the patient visited our hospital due to massive proteinuria. Repeated renal biopsy and re-evaluation of the first biopsy obtained 4 years previously revealed monoclonal immunoglobulin deposition in the glomeruli. A bone marrow examination was performed to exclude hematologic malignancy, and a diagnosis of PGNMID was established. The patient showed remission after four cycles of a bortezomib + cyclophosphamide + dexamethasone scheme. CONCLUSION PGNMID is usually misdiagnosed as MsPGN or membranoproliferative glomerulonephritis. Although it often occurs in middle-aged and elderly individuals, it cannot be readily excluded in young people, even when serum immunofixation electrophoresis is negative. IgG subtype and light chain staining are necessary when this disease is highly suspected. An accurate diagnosis at the earliest stage may avoid the overuse of glucocorticoids and immunosuppressants.

A case of proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) that responded favorably to steroid therapy

“…However, PGNMID cases with the membranous pattern responded favorably to steroid treatment [7,8]. Three previous PGNMID cases with the mesangial proliferative pattern also achieved a favorable renal prognosis with steroid therapy (Table 2) [9][10][11][12]. Based on these findings, the histological feature of our case, the mesangial proliferative pattern, may have contributed to the stable renal The IgG subclass found in glomerular deposits might influence the clinical features of PGNMID.…”

“…Overall, the steroid responsiveness of PGNMID with mesangial proliferative pattern was favorable, but there was a case with IgG3κ deposits whose response to the steroid was poor [12]. This case achieved partial remission with a clone-directed therapy with bortezomib, cyclophosphamide, and dexamethasone [12]. Considering these findings together, PGNMID with IgG3 deposits might need an aggressive treatment, because of the strong complement activity of IgG3.…”

“…In the reported cases of mesangial proliferative pattern, IgG1, 2, or 3 were detected (Table 2). Overall, the steroid responsiveness of PGNMID with mesangial proliferative pattern was favorable, but there was a case with IgG3κ deposits whose response to the steroid was poor [12]. This case achieved partial remission with a clone-directed therapy with bortezomib, cyclophosphamide, and dexamethasone [12].…”

A Review on the Diagnosis and Treatment of Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposits

“…14,17,18 In addition, spontaneous remission of PGNMID patients that occurs at a young age or after viral infection may suggest that pathogenesis also involves induction of B-cell repertoires by viral or other antigenic stimulation mechanisms, producing low clonal nephrotoxic IgG3. [19][20][21][22]…”