Light Chain-Only Immunotactoid Glomerulopathy: A Case Report #MMPMID36328099
Bu L; Javaugue V; Chauvet S; Napier J; Dasari S; Theis JD; Vrana JA; McPhail ED; Nasr SH
Am J Kidney Dis 2023[May]; 81 (5): 611-615 PMID36328099show ga
The monotypic variant of immunotactoid glomerulopathy (ITG), strongly associated with low-grade lymphoproliferative disorders, is characterized histologically by glomerulonephritis and microtubular deposits of monoclonal immunoglobulin G (IgG). We report a patient with high-risk kappa light chain multiple myeloma who presented with acute kidney injury, hematuria, proteinuria, and hypocomplementemia. Kidney biopsy revealed immunotactoid glomerulopathy concomitant with kappa light chain myeloma cast nephropathy. The glomerular microtubular deposits stained for kappa light chain and C3 only. Proteomic analysis of glomeruli and atypical casts detected kappa light chain constant domain and a single VL variability subgroup (IGKV3) in both glomeruli and casts (without gamma, alpha, or mu heavy chain or lambda light chain). C3, C5, C6, C7, and C9 were detected in glomeruli. No autoantibodies against alternative pathway of complement proteins were detected. Despite clone-directed chemotherapy, the patient remained on dialysis treatment. For this light chain-only variant of immunotactoid glomerulopathy, pathogenesis potentially involves activation of the alternative pathway of complement by a nephrotoxic kappa light chain.
Am+J+Kidney+Dis 2023 ; 81 (5): 611-615
