Late-Onset Post-transplant Lymphoproliferative Disorders Presenting with Sudden Massive Abdominal Ascites Effusion: A Case Report

Introduction: Late-onset post-transplant lymphoproliferative disorders (PTLD) are increasingly recognized in recent literature. Late-onset PTLD exhibits distinct characteristics regarding the primary lymphoma lesion, Epstein-Barr virus (EBV) association, and risk factors. Here, we present a case of non-EBV-associated late-onset PTLD marked by sudden massive abdominal ascites, later diagnosed as peritoneal lymphomatosis. Case Description: A 65-year-old man underwent ABO-compatible living-donor kidney transplantation (KT) 8 years ago for end-stage kidney disease due to nephrosclerosis. Both donor and recipient were EBV-seropositive pre-KT. Post-transplantation, the patient maintained a stable course under a standard immunosuppression with steroids, tacrolimus, and mycophenolate mofetil. Eight years post-KT, however, he presented with anorexia and sudden massive abdominal ascites (Figure). Ascitic fluid cytology revealed diffuse large B-cell lymphoma (DLBCL). Because of negative serum EBV-DNA, non-EBV-associated PTLD was diagnosed. Imaging studies showed diffuse omental and peritoneal thickening without solid organ tumors or lymphadenopathy (Figure), indicating that the primary lesion of PTLD was peritoneal lymphomatosis. Reduced immunosuppression and R-CHOP chemotherapy induced DLBCL remission, resolving ascites without graft function deterioration. Discussion: Late-onset PTLD often presents with extranodal lesions and involves extra-transplanted organs. Peritoneal lymphomatosis is rare not only as a primary lesion of PTLD but also as a primary lesion of lymphoma in non-transplant patients. Notably, literature of peritoneal lymphomatosis lacks KT case reports, with focus mainly on liver transplantations. Although PTLD with peritoneal lymphomatosis is a rare condition, clinicians should consider it as a differential diagnosis when encountering sudden massive abdominal ascites following kidney transplantation.