Gastroesophageal Junction Neuroendocrine Carcinoma

**Semantic type:** Neoplastic Process

**Definition:** An aggressive high-grade carcinoma with neuroendocrine differentiation that arises from the gastroesophageal junction. It is composed of malignant small or large cells. The mitotic count is more than 20 per 2 mm2 and/or the Ki-67 index is more than 20%.

**Synonyms:** - Gastroesophageal Junction NEC