CD20 negative posttransplant lymphoproliferative disorder after liver transplantation in complete remission with rituximab

Post-transplant Lymphoproliferative Disorders (PTLD) are an uncommon but serious complication after solid organ transplantation; they appear as a wide spectrum of associated lesions ranging benign proliferative disorders to malignant tumors, which respond differently to diverse therapies. The incidence varies depending on multiple risk factors such as type of trasplanted organ, immunosuppression intensity, number of episodes of acute rejection and Epstein Barr Virus (EBV) serologic status prior to organ transplantation. In rare cases the PTLD has debuted as a biliary tree stricture mass; although most lesions are positive for CD20 staining, they can be negative. A wide variety of therapies have been described for PTLD patients, starting by reducing immunosupression therapy, and then a diversity strategies, including rituximab alone or combined with chemotherapy. We report the case of a 68 years-old male patient who developed PTLD one year after undergoing liver transplantation procedure. He presented initially as a cholestatic syndrome. He was treated by reducing immunosuppression and thereafter with two cycles of rituximab monotherapy, achieving initially 80% of tumor response. We could not continue established immunotherapy because of a low level T CD4 cell count and because of achieved MRI-confirmed complete remission after two-month follow up subsequent to two rituximab cycles, which persists, at least, eighteen months later. Possible explanations for this findings and general approach to these patients are discussed based on the case.