Duodenal mantle cell lymphoma in a patient with advanced sigmoid adenocarcinoma.

While colorectal cancer is one of the most commonly encountered gastrointestinal malignancies, primary lymphoma is an uncommon neoplasm of the gastrointestinal tract. The duodenum is not a common location for the recurrence of colon cancer or of primary gastrointestinal lymphoma. Studies regarding mantle cell lymphoma (MCL) as a secondary synchronous or metachronous malignancy are limited. Here we report a patient who received concurrent chemoradiotherapy for his advanced sigmoid adenocarcinoma and developed MCL in the duodenal bulb 20 months later. Suspected lesions should be biopsied and examined for a secondary neoplasm, especially when they appear in an uncommon location for metastasis or direct invasion.