Light Chain-Only Immunotactoid Glomerulopathy: A Case Report

Am J Kidney Dis. 2022 Oct 31;S0272-6386(22)00993-3. doi: 10.1053/j.ajkd.2022.08.025. Online ahead of print.


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 κ light chain multiple myeloma who presented with acute kidney injury, hematuria, proteinuria, and hypocomplementemia. Kidney biopsy revealed immunotactoid glomerulopathy concomitant with κ light chain myeloma cast nephropathy. The glomerular microtubular deposits stained for κ light chain and C3 only. Proteomic analysis of glomeruli and atypical casts detected κ light chain constant domain and a single VL variability subgroup (IGKV3) in both glomeruli and casts (without γ, α, or μ heavy chain or λ 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 κ light chain.

Keywords: Alternative pathway of complement; Case report; Cast nephropathy; Dialysis; Immunoglobulin deposits; Immunotactoid glomerulopathy (ITG); Kappa light chain; Monoclonal light chain; Proliferative glomerulonephritis; Renal failure.

Publication types

  • Case Reports