Light chain deposition disease affecting the gastrointestinal tract in the setting of post-living donor kidney transplantation.

Light chain deposition disease (LCDD) is an uncommon, clonal plasma cell proliferative disorder, in which monoclonal immunoglobulin light chains deposit in various tissues, resulting in organ dysfunction. Gastrointestinal (GI) involvement has been described in both primary and secondary amyloidosis, but has rarely been reported in LCDD, and only as an incidental finding. We report a case of LCDD in living related kidney transplant recipient presenting with severe GI dysmotility, weight loss and progressive allograft dysfunction. A diagnosis of LCDD was based on the kidney biopsy findings in the failing renal allograft, along with the presence of excess serum free kappa light chains and abnormal kappa:lambda ratio. Subsequent review of GI biopsies confirmed kappa light chain immunoglobulin deposition within the stomach. Further investigation suggested additional hepatic and cardiac involvement. The patient went on to receive bortezomib, achieving a biochemical response and stabilization of his advanced renal dysfunction; however, bortezomib was discontinued due to toxicity. The patient was subsequently treated with lenalidomide and dexamethasone, which were better tolerated. Further biochemical response and resolution of the GI symptoms was observed after 10 months of treatment. In summary, we present the first case of LCDD with symptomatic GI involvement, in which the diagnosis was established by intestinal biopsies. Our report also highlights the feasibility and effectiveness of lenalidomide in the treatment of LCDD.