Ulcerative Colitis Diagnosed in a Patient after Primary Rectal Marginal Zone B-Cell Lymphoma of Mucosa-Associated Lymphoid Tissue (MALT) Treated

A 39-year-old woman presented with loose stool and rectal bleeding for 1 year. A colonoscopy was performed and revealed proctitis. Rectal biopsy revealed a diagnosis of rectal marginal B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). She was treated with a course of chemotherapy rituximab. However, her symptoms persisted and a repeat colonoscopy showed features consistent with ulcerative colitis. She received topical mesalazine and her symptoms resolved. Another repeat colonoscopy showed evidence of inactive chronic colitis only. This is a rare report of ulcerative colitis being diagnosed after rectal MALT was treated. It is possible that she might have long-standing ulcerative colitis that was undiagnosed, with the rectal MALT lymphoma masking the features of ulcerative colitis. A few treatment modalities are available, and the prognosis in general is good.