Complete remission of a primary rectal lymphoma on ulcerative colitis, after withdrawal of azathioprine and infliximab.

A 45-year-old woman was diagnosed with ulcerative colitis and treated with mesalazine, prednisone and, finally, azathioprine and infliximab. Colonoscopy revealed a rectal ulcer, identified by biopsy as a large cell B-lymphoma, positive for leukocyte common antigen (LCA), CD 20 and LMP-1 and negative for CD 3. Three months after withdrawal of all immunosuppressors, a proctocolectomy was performed. The resection specimen contained an area of B-cell polymorphic hyperplasia, but no residual tumour. The patient remains well after 2 years of follow-up, without any further antineoplastic therapy.