gastric small cell neuroendocrine carcinoma (MONDO_0006229, a Monarch Disease Ontology identifier) is an aggressive, high-grade and poorly differentiated carcinoma with neuroendocrine differentiation that arises from the stomach. It is characterized by the presence of malignant small cells. Also known as: Oat cell carcinoma of stomach, Oat cell carcinoma of the stomach, gastric Oat cell carcinoma, gastric small cell carcinoma, small cell carcinoma of stomach, small cell carcinoma of the stomach, stomach small cell carcinoma.