A Case of Post-transplant Lymphoproliferative Disorder After Successful Treatment of Islet Transplantation Without Graft Rejection.

Post-transplant lymphoproliferative disorder (PTLD) is a lymphoid or plasmacytic proliferation that occurs in association with immunosuppression and is recognized as a relatively rare but serious complication following solid organ transplantation; however, PTLD following islet transplantation is extremely rare, and its optimal management remains unclear. We report the case of a 55-year-old woman with a history of type 1 diabetes mellitus who underwent living-donor kidney transplantation followed by deceased-donor pancreas transplantation and subsequently received three islet transplantations due to recurrent diabetes. Five years after the final islet transplantation, she developed persistent fever, and fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) revealed small intestinal wall thickening and lymphadenopathy in the mesentery and axilla. A biopsy confirmed the diagnosis of diffuse large B-cell lymphoma (DLBCL)-type PTLD. Immunosuppressive therapy was carefully adjusted without complete discontinuation, and initial treatment with four cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) achieved partial remission. This was followed by four cycles of DA-EPOCH-R (dose-adjusted toposide, prednisone, vincristine, cyclophosphamide, hydroxydaunorubicin, and rituximab), which led to complete remission of PTLD. Notably, islet graft function was preserved throughout treatment, and no recurrence of PTLD was observed during follow-up. To our knowledge, this is the first reported case of PTLD following islet transplantation in Japan, and it highlights the potential for achieving remission with preserved graft function through careful immunosuppressive adjustment and appropriate chemotherapy.