The tumor that is the subject of this study contained well-differentiated adenocarcinoma and poorly differentiated NEC components, accompanied by a high mitotic rate and a high Ki-67 LI in both components, consistent with the diagnostic criteria for MANEC.[1] Thus, we report here on a rare case of a MANEC. The gene discussed is MKI67; the disease is digestive system mixed adenoneuroendocrine carcinoma.