Synchronous duodenum and descending colon metastasis from primary lung neuroendocrine small-cell carcinoma: A case report and review of the literature.

Gastrointestinal tract metastasis of lung cancer is recognized synchronously with or rarely before diagnosis. It is generally recognized after the diagnosis of lung cancer. These patients often have other concurrent body metastases. Prognosis is poor, and survival expectation is short. The most common metastases to the gastrointestinal tract are squamous and large cell lung cancer metastases. Our aim is to emphasize the importance of immunohistochemical examination for masses in the gastrointestinal tract and to present this rare case of synchronous duodenal and colonic metastases of small-cell lung cancer.