Recurrence of light chain crystalline podocytopathy and tubulopathy after kidney transplantation achieving remission with an antimyeloma regimen.

Light chain crystalline podocytopathy (LCCP) and tubulopathy (LCCT) are rare renal manifestations of monoclonal gammopathy, most often linked to an IgG κ paraprotein. Definitive diagnosis is challenging and typically requires electron microscopy (EM) of a renal biopsy. We report a 65-year-old patient presenting with rapidly progressive chronic kidney disease requiring dialysis despite inconclusive histologic examinations and stable immunohematologic parameters. Twenty-eight months after kidney transplantation, an unexplained rise in serum creatinine prompted repeat allograft biopsy including EM, which disclosed crystalline inclusions within podocytes and proximal tubular cells, consistent with combined LCCP and LCCT in the setting of newly diagnosed multiple myeloma. Proteomic analysis of kidney crystals and bone marrow immunoglobulin high-throughput sequencing detected the same IGKV1-33 sequence. The patient was treated with clone-directed immunochemotherapy (daratumumab, lenalidomide, dexamethasone) for 2 years, along with tailored adjustment of the immunosuppressive regimen. Both renal and hematologic responses were favorable. To our knowledge, this is the first reported case of posttransplant LCCP and LCCT recurrence successfully managed with targeted therapy.