A case of recurrent proliferative glomerulonephritis with monoclonal IgG deposits or de novo C3 glomerulonephritis after kidney transplantation

Updates on C3 Glomerulopathy in Kidney Transplantation: Pathogenesis and Treatment Options

C3 glomerulopathy is a rare disease, characterized by an abnormal activation of the complement's alternative pathway that leads to the accumulation of the C3 component in the kidney. The disease recurs in more than half of kidney transplant recipients, with a significant impact on graft survival. Recurrence of the primary disease represents the second cause of graft loss after organ rejection. In C3 glomerulopathy, there are several risk factors which can promote a recurrence during transplantation, such as delayed graft function, infection and monoclonal gammopathy. All these events can trigger the alternative complement pathway. In this review, we summarize the impact of C3 glomerulopathy on kidney grafts and present the latest treatment options. The most widely used treatments for the disease include corticosteroids and mycophenolate mofetil, which are already used chronically by kidney transplant recipients; thus, additional treatments for C3 glomerulopathy are required. Currently, several studies using anti-complement drugs (i.e., eculizumab, Ravalizumab, avacopan) for C3 glomerulopathy in kidney transplant patients are ongoing with encouraging results.

Steroid-sensitive recurrent mesangial proliferative glomerulonephritis with monoclonal IgG deposits

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a rare kidney disease. The predominant pathological finding of PGNMID is the presence of monoclonal Ig deposits on the glomerular basement membrane (GBM). However, there is some variation in deposition pattern in this kidney disease. We report a case of steroid-sensitive recurrent mesangial proliferative type of PGNMID. A 40-year-old female noticed lower leg pitting edema and polyuria. Approximately 10 days prior to the first clinic visit, she was diagnosed with nephrotic syndrome based on the laboratory data of urine and blood. Immunological and hematological examination revealed no abnormality. However, kidney biopsy specimens showed mild mesangial cell proliferation and mesangial matrix accumulation on light microscopic findings. Regarding immunofluorescence staining, granular deposits of IgG, C1q, and β1c were observed on GBM and mesangial area. Granular deposits of IgG3 and λ were also observed on GBM and mesangial area. Moreover, negative results were obtained for the phospholipase A2 receptor antibody and thrombospondin type-1 domain-containing 7A. Electron microscopy revealed highly electron dense deposits mainly in the mesangial region. Kidney biopsy showed mesangial proliferative glomerulonephritis characterized by monoclonal Ig deposition of IgG3/λ. Steroid therapy was initiated, and complete remission was achieved on day 36. After the discontinuation of steroid therapy, proteinuria recurred and second kidney biopsy findings were almost similar to the first biopsy. However, complete remission was achieved with steroid therapy. This is a rare recurrent case of steroid-sensitive PGNMID. The pathological feature of this case was mesangial proliferative glomerulonephritis with Ig deposition of IgG3/λ.

Membranoproliferative glomerulonephritis with deposition of monoclonal IgG evolved from polyclonal IgG: a case report with two consecutive renal biopsies

BACKGROUND

Proliferative glomerulonephritis with monoclonal Immunoglobulin (G) deposits (PGNMID) is a rare kind of MGRS with intact monoclonal IgG deposition. Seventy percent of PGNMID patients were negative for M-spike.

CASE PRESENTATION

A 51-year-old Chinese woman presented with 16-month history of chronic nephritic syndrome. Her first biopsy showed a MPGN pattern, and the IF showed polyclonal IgG deposition but with IgG3λ dominance, MGRS was highly suspected. But the serum/urine IFE and bone marrow examination was negative for monoclonal gammopathy. She was treated with RAS inhibitors, and monitored carefully in the outpatient clinic. When the proteinuria was not controlled by RAS inhibitors, immunosuppressive agents were initiated. The second biopsy was done due to her acute kidney injury 9 months later, showing a MPGN pattern with acute tubulointerstitial disease, but the IF showed monoclonal IgG3λ deposition. The κ light chain, IgG1, IgG2 and IgG4 were absent. Electron microscopic examination revealed electron-dense deposits in the mesangial, subendothelial and subepithelial area which is the same as the first renal biopsy. The final diagnose of this patient was PGNMID (IgG3λ) with non-organized deposits. Repeated serum/urine IFE and free light chain still failed to identify monoclonal gammopathy. The patient was treated with steroid and cyclophosphamide, and her serum creatinine decreased.

CONCLUSIONS

Some of the PGNMID patients may be derived from polyclonal immune complex mediated glomerulonephritis.