Peritoneal lymphomatosis as a rare entity of post-transplant lymphoproliferative disorder after kidney transplantation: a case report.

Post-transplant lymphoproliferative disorder (PTLD) is a severe complication of solid organ transplantation, and its manifestation as peritoneal lymphomatosis (PL) is extremely rare. This report describes the case of a 65-year-old kidney transplant recipient who presented with massive ascites as the initial symptom of PTLD 8 years post-transplantation. The patient experienced a sudden onset of ascites, and both his serum and ascitic fluid showed elevated lactate dehydrogenase (LDH) levels along with characteristic computed tomography (CT) findings, both of which raised the suspicion of lymphoma. The cytology of the ascitic fluid confirmed the diagnosis of peritoneal primary diffuse large B-cell lymphoma, leading to an early diagnosis of PL and management strategies. Although the patient developed tumor lysis syndrome soon after chemotherapy, prompt management led to complete remission. When ascites is observed in post-transplant recipients, it is essential to consider PTLD, recognize the diagnostic value of LDH levels and CT imaging, and emphasize the importance of early intervention to achieve favorable outcomes. To the best of our knowledge, this is the first reported case of PL in a kidney transplant recipient.