An aggressive, high-grade, and poorly differentiated carcinoma with neuroendocrine differentiation that arises from the colon. It is characterized by the presence of malignant small cells. The disease is colon small cell neuroendocrine carcinoma (MONDO_0003978). Also known as: Oat cell carcinoma of colon, Oat cell carcinoma of the colon, Oat cell colon carcinoma, colon Oat cell carcinoma, colon small cell carcinoma, colon small cell neuroendocrine cancer, colonic Oat cell carcinoma, colonic small cell carcinoma.