Colorectal lymphoma.

Lymphoma involving the colon and rectum is rare and can occur either as primary colorectal lymphoma or as a manifestation of systemic disease. Most patients with primary colorectal lymphoma present with abdominal pain, and obstruction is unusual. Although lesions may be evident on radiographic studies, the findings are generally nonspecific. Historically, aggressive B-cell lymphomas have been the most common gastrointestinal lymphomas reported in the literature. However, recent reports suggest increased rates of mucosa-associated lymphoid tissue (MALT) lymphoma and mantle cell lymphoma (MCL) with increased surveillance.1 Most patients with colorectal lymphoma undergo surgery, but multiagent chemotherapy remains the mainstay of treatment. B-cell lymphomas tend to be most aggressive, with a median survival of about 2 years.