Intestinal Peripheral T-Cell Lymphoma in a Patient with Ankylosing Spondylitis Under Treatment with Infliximab: A Case Report and Review of the Literature.

Background: Recent literature involves many cases with lymphoma and ankylosing spondylitis (AS) with or without the use of TNF inhibitors. Herein, we report a patient, a 56-year-old Human Leukocyte Antigen-B27 (HLA-B27) positive man with four years history of AS who was still under treatment with infliximab with clinical remission. He was admitted with a new-onset, 6-week history of bloody diarrhoea with mucus, abdominal pain, fever, and weight loss. An ileocolonoscopy showed linear ileocecal valve ulcers. Histopathological findings of ileocecal valve ulcers revealed peripheral T-cell lymphoma of the small intestine. Infliximab was interrupted because of the possible progression of the lymphoma Methods: We aimed to emphasize the underlying potential pathogenic mechanisms and to review the related literature. A literature search was conducted in the PubMed database between January 1980 and November 2020. The keywords including 'ankylosing spondylitis' and 'lymphoma' were used. Conclusion: TNFi use, immunosuppression, and chronic inflammation may be related to the development of lymphoma in chronic inflammatory diseases. Ileocecal valve involvement should not be interpreted as inflammatory bowel disease, infection, or vasculitis in the presence of red flags.