Source:http://linkedlifedata.com/resource/umls/id/C2987128
NCI: A high grade poorly differentiated carcinoma arising from the gastrointestinal system. It is composed of small or large neoplastic cells that express immunohistochemical evidence of neuroendocrine differentiation. There is marked nuclear atypia, necrosis, and more than 20 mitoses per 10 HPF.