Diagnosis of light‑chain deposition disease after renal transplantation: A case report and literature review.

Light chain deposition disease (LCDD) is a rare, clonal plasma cell proliferative condition. The deposition of nonamyloid monoclonal immunoglobulin light chains predominantly affects the kidneys, which may lead to end-stage renal disease, eventually requiring renal replacement therapy. The present study reported a rare case of LCDD that was confirmed after renal transplantation. A 49-year-old man initially presented with heavy proteinuria, hypoproteinemia, hyperlipidemia and renal insufficiency. The patient was diagnosed with nephrotic syndrome and pathological examination revealed fibrillary glomerulonephritis in 2014. Treatment was started with prednisolone. About 5 years later, the patient began to receive continuous hemodialysis due to worsening serum creatinine levels. Renal allograft transplantation was performed in 2020 and dialysis independence was achieved. Laboratory findings before renal transplantation revealed that serum and urine immunofixation electrophoresis was negative. Allograft kidney biopsy established the pathological diagnosis of LCDD at >1 year after renal transplantation for renal dysfunction. The treatment is challenging due to the lack of generally accepted standard treatment practices. Administration of bortezomib combined with dexamethasone was started. As anemia and renal failure developed progressively, the treatment was switched to anti-CD38 antibody and continuous hemodialysis was restarted. The best response achieved was hematological partial response and relief of anemia. However, the patient's renal function did not improve and he remains to have end-stage kidney disease. LCDD is easily missed in cases in which serum and urine immunofixation electrophoresis is negative. Hence, early recognition of LCCD based on kidney biopsy is important. To the best of our knowledge, the use of anti-CD38 antibody therapy in patients with LCDD is rarely reported. Anti-CD38 antibody is effective in treating LCDD, but it may not reverse the marked deterioration of renal function.