[Colorectal synchronism: ascending colon adenocarcinoma and small-cell neuroendocrine carcinoma of the rectum].

Colorectal cancer (CRC) is the third most frequent cancer in the world and the second cause of death of neoplastic origin. Synchronism in CCR is approximately 3-6%. The gastrointestinal tract is the most frequent place where neuroendocrine neoplasms (NNE) settle and a special type of these neuroendocrine carcinomas (CNE) are rare.