Synchronous association of two neuroendocrine gastroenteropancreatic tumors, an adenocarcinoma of the cecum, and a Meckel's diverticulum: a case report.

Neuroendocrine gastroenteropancreatic tumors constitute a heterogeneous group of neoplasms, with the primary tumors being located in the gastric mucosa, pancreas, and small and large intestine. The development of a second primary malignancy in patients with these tumors is a well-described phenomenon, and the reported incidence ranges from 12% to 46%. The most common site of associated noncarcinoid malignancies is the gastrointestinal tract, which involves from 30% to 60% of the tumors. We report a case of concurrent colon carcinoma and two neuroendocrine tumors of the duodenum.