Gastric Mixed Adenoneuroendocrine Carcinoma with a Trilineage Cell Differentiation: Case Report and Review of the Literature

Most gastric neuroendocrine tumours are well differentiated and considered as neuroendocrine neoplasms, whilst poorly differentiated lesions are considered as neuroendocrine carcinomas and account for only 6–16% of gastric neuroendocrine tumours. Gastric mixed adenoneuroendocrine carcinomas are rare malignancies usually composed of a neuroendocrine carcinoma and an adenocarcinoma with a variable grade of differentiation. Here, we report an unusual and rare gastric mixed adenoneuroendocrine carcinoma with a trilineage cell differentiation including a neuroendocrine carcinoma, an adenocarcinoma and a squamous cell carcinoma. A brief discussion of the histopathological features, biological behaviour and treatment of this rare tumour type is presented.