1489 “Bi-Morphic” Post-Transplant Lymphoproliferative Disorder Masquerading as Inflammatory Bowel Disease

Abstract

INTRODUCTION: Post-transplant lymphoproliferative disorder (PTLD) is a serious complication occurring in up to 30% of post-transplant patients, usually within the first year; however, recurrent PTLD or development of multiple histologic subtypes is rare.1 Relevant to gastroenterologists, GI tract involvement can occur in up to 25% of cases and present as nonspecific clinical symptoms, abdominal pain, bleeding, or perforation.2 CASE DESCRIPTION/METHODS: An 80-year-old African American male with a past medical history of living-donor kidney transplant presented to clinic to undergo surveillance colonoscopy. Nine months post-transplant, the patient was diagnosed with early PTLD on colonoscopy and treated with 4 cycles of rituximab without evidence of disease on repeat colonoscopy or PET scan. Follow up colonoscopy at 5 years did not show any recurrence of disease and the patient was recommended to undergo his next colonoscopy in another 5 years (10 years following PTLD treatment). Repeat colonoscopy at this time found multiple inflammatory polyps at the ileocecal valve and in the transverse and sigmoid colon. Additionally, the rectosigmoid colon showed evidence of moderate inflammation (Figure 1). Pathology reports indicated polyps of the ileocecal valve were consistent with polymorphic PTLD, whereas the biopsies of the rectosigmoid colon showed monomorphic PTLD (Figure 2). The patient was referred to Oncology and is currently undergoing repeat rituximab therapy for monomorphic PTLD and a dose reduction of immunosuppressants for polymorphic PTLD. DISCUSSION: Importantly, even though rates of PTLD are typically lowest for renal transplants (0.8-2.5%), early and recurrent PTLD is still possible in this population.3 Our patient, despite a previous response to rituximab, demonstrated evidence of rare, recurrent PTLD in addition to multiple pathologic subtypes spread diffusely throughout the colon. In particular, the emergence of monomorphic PTLD carries the worst prognosis with survival rates ranging from 25-60%.5,6 Given the frequency of GI tract involvement, it is essential gastroenterologists maintain high suspicion for PTLD in patients with prior transplantation and have a lower threshold for biopsy, as our case demonstrates advanced disease appearing endoscopically as inflammatory changes. Importantly, this recurrence was found 10 years after initial diagnosis, which signifies the importance of surveillance colonoscopy for early detection, monitoring for recurrence, and establishing disease prognosis in PTLD.