Diffuse large B-cell lymphoma (DLBCL) commonly affects the gastrointestinal (GI) tract, although primary DLBCL rarely occurs in the colon. Primary colorectal lymphoma is a surprisingly rare diagnosis, accounting for a minute percentage of GI lymphomas and colorectal malignancies. We present an interesting case of an immunocompromised young adult female who was diagnosed with DLBCL confined to a cecum polyp after she underwent a colonoscopy for a GI bleed. The lymphoma presented endoscopically as a semi-sessile polyp in the cecum that was successfully removed. The patient was treated with appropriate therapy of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP).

Extranodal marginal zone lymphoma (EMZL) of mucosa-associated lymphoid tissue (MALT) commonly affects the gastrointestinal (GI) tract but rarely occurs within the colon. Colonic EMZL is a rare diagnosis accounting for 2.5% of EMZL and less than 0.5% of colon cancers. We present a unique case of asymptomatic colonic EMZL diagnosed on a routine surveillance colonoscopy. The lymphoma was confined to a single colonic polyp presenting endoscopically as a sessile polypoid lesion at the recto-sigmoid junction. The patient was successfully treated with polypectomy with no recurrence of the disease.