Colorectal lymphoma.

Extranodal lymphomas account for a third of all cases of non-Hodgkin lymphoma with the gastrointestinal tract being the most common extranodal site. The most common location is the stomach followed by the small intestine, colon and rectum. Colorectal lymphomas are rare and comprise 10-20% of all gastrointestinal lymphomas and only 1% of all colorectal malignancies. Presenting symptoms include abdominal pain, weight loss, and anorexia. Diagnosis depends on the clinical setting with elective cases being diagnosed with colonoscopy and emergent cases being diagnosed in the operating room. Colonic lymphomas are frequently located proximal to the hepatic flexure. Management depends on the aggressiveness of the lymphoma subtype. Indolent tumors, which are resistant to standard chemotherapeutic regimens, are treated with surgical resection. Aggressive lymphoma subtypes are managed with chemotherapy and surgery with late-stage disease patients being referred to clinical trials.