Membranous nephropathy with light chain restricted deposits

The literature on membranous nephropathy (MN) with monoclonal deposits on immunofluorescence (IF) and their outcome is very scarce. We report our experience of managing five patients with this clinical entity. The mean age of the patients was 33.2 ± 6.55 years. The mean proteinuria, serum albumin and serum creatinine was 5.73 ± 2.17 g/day, 2.86 ± 0.51 g/dL and 1.34 ± 1.19 mg/dL, respectively. None of the patients had a lymphoproliferative disorder. Only one patient had an elevated free light chain ratio. Four (80%) patients were M-type phospholipase A2 receptor (PLA2R) negative (tissue and serum), and one (20%) was PLA2R related. Three (60%) cases had monoclonal IgG3/k, one IgG3/λ, whereas one patient with PLA2R positivity had an IgG3/IgG4k subtype. Two (67%) patients treated with cyclical cyclophosphamide and steroids (cCYC/GC) achieved complete remission and one patient (33%) with elevated baseline creatinine had a reduction in serum creatinine with persistent proteinuria at the end of the 12th month of follow-up. One patient with PLA2R positive MN was treated with Rituximab and is in complete remission. The patient with an elevated free light chain at baseline was treated with Bortezomib/Thalidomide/Dexamethasone, had complete remission at 12 months, however, had a progressive rise in creatinine over the next 40 months of follow-up. The current series, though limited by numbers, documents the efficacy of conventional therapies in non-malignant associated MN with monoclonal deposits on IF.