Rare Presentation of Post-Transplant Plasmablastic Lymphoma: Colonic Ulcer With Perforation

A 69-year-old lady with diseased kidney transplant 20 years ago presented with few weeks of loose stool and weight loss. She was recently diagnosed with cytomegalovirus pp65 antigenaemia and received valganciclovir therapy. Microbiological examination of feces did not reveal any infectious cause. After hospitalization, she developed profuse fresh rectal bleeding. Colonoscopy revealed a large deep ulcer with irregular border over the descending colon which occupied more than half of the luminal circumference (Figure A). Biopsies of the ulcer showed diffuse growth of lymphoma cells which showed plasmablastic features (Figure B). Immunohistochemical study showed that the tumor cells were positive for multiple myeloma 1 (MUM1), with patchy staining for CD20 and paired box 5 (PAX5). Light chain restriction for kappa was demonstrated. In situ hybridization study for Epstein-Barr virus–encoded RNA was positive (Figure C). The diagnosis was consistent with monomorphic B-cell post-transplant lymphoproliferative disorder, pathologically plasmablastic lymphoma. The patient then developed severe abdominal pain. Abdominal computerized tomography revealed pneumoperitoneum with intraperitoneal fluid (Figure D). Laparotomy confirmed colonic perforation requiring transverse colectomy. Plasmablastic lymphoma is a rare but aggressive type of B-cell lymphoma which seldom involves the gastrointestinal tract. Awareness of this entity especially in immunocompromised patients is essential to establish an early diagnosis which can allow timely treatment.