Post-transplant lymphoproliferative disorder localized in the colon after liver transplantation: report of a case.

Post-transplant lymphoproliferative disorder (PTLD) is a life-threatening complication of any organ transplantation. It is more common in children than in adults, and the risk factors include Epstein-Barr virus (EBV) infection and immunosuppression. We report a case of colonic marginal zone B-cell lymphoma occurring 4 years after liver transplantation in a 52-year-old man who had been taking immunosuppressive agents, namely, cyclosporin, mycophenolate mofetil (MMF), and prednisolone. A routine follow-up colonoscopy showed a 2.0-cm diffuse nodular transverse colon polyp covered with erosive mucosa. Snare polypectomy was done without any complications. Immunohistochemical staining was positive for CD3 and CD20 in the interstitially scattered small lymphocytes and negative for Bcl-2, revealing marginal zone B-cell lymphoma. EBV quantitative polymerase chain reaction was less than the detection limit (<10 copies/5 microl whole blood). Extraintestinal whole-body screening was negative. The patient underwent right hemicolectomy after colonoscopic tattooing for positive resection margins on snare polypectomy. Surgical pathology revealed no evidence of residual lymphoma. Treatment consisted of colonic resection and reduction of the doses of immunosuppressants. The patient is currently under close surveillance without any signs of recurrence.