Large bowel (colorectal) lymphoma is a very rare tumor, accounting for <0.5% of primary colorectal malignancies, ~1.5% of all lymphomas, and ~15% of gastrointestinal lymphomas. Large bowel lymphoma differs from gastric and small bowel lymphoma in clinical presentation, management, and prognosis.
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Epidemiology
Most commonly occurs in patients in their 40s to 60s, with increasing incidence with age. There is a slight male predominance (M:F = 1.5:1) 2.
Clinical presentation
As with other colorectal tumors, primary symptoms are weight loss, pain and, less commonly, per rectal bleeding 2. Large bowel obstruction and perforation are rare.
Pathology
Diffuse large B-cell lymphoma is the most common subtype (~65%) of large bowel lymphoma. Less common subtypes include mucosa-associated lymphoid tissue (MALT) lymphoma and mantle cell lymphoma (MCL) 5.
The underlying etiology is unknown but an infective/inflammatory pathogenesis is suspected as there is higher incidence in patients with HIV/AIDS, inflammatory bowel disease, and post-transplantation immunosuppression 1.
The majority (~70%) of large bowel lymphomas occur in the right colon 2.
Radiographic features
Compared to colorectal adenocarcinoma, lymphoma affects longer and multiple colonic segments 4, mostly characterized by circumferential wall thickening.