Diffuse Large B-cell Lymphoma Arising in a Patient with the Long-term Remission of Left-sided Ulcerative Colitis: A Case Report.

Malignant lymphoma in ulcerative colitis (UC) is uncommon, and diffuse large B-cell lymphoma (DLBCL) without immunosuppressive or biologic therapy is particularly rare. We report a case of an Epstein-Barr virus-negative patient with long-standing left-sided UC in remission who developed rapidly enlarging synchronous DLBCL lesions in the ascending and sigmoid colon. The diagnosis was made endoscopically and histologically, and treatment with Pola-R-CHP followed by rituximab achieved a complete remission. A literature review showed that most UC-associated lymphomas are EBV-positive DLBCL related to immunosuppression. Although malignant lymphoma is rare in patients with UC, it can occur and therefore should be considered during surveillance colonoscopy.