Mixed neuroendocrine and non-neuroendocrine neoplasia (MiNEN) of the stomach

From the latest WHO classification of neuroendocrine neoplasms (NENs), the term MiNENs refers to mixed neuroendocrinenon-neuroendocrine tumors. A neuroendocrine component coexists with a non-neuroendocrine one in them. They are morphologically and/or immunohistochemically validated. The non-neuroendocrine component implicates adenocarcinoma, apart from other histological subtypes of carcinomas, such as squamous cell carcinoma. The neuroendocrine component can be represented by a high-grade tumour (HGNEC) in addition to neuroendocrine cancer. Gastric NENs also have subgroups of MiNENs such as mixed adenoneuroendocrine carcinoma (Mixed-adenocarcinoma-NEC), which includes both, small or large cell type, neuroendocrine carcinoma (NEC) and mixed adenoneuroendocrine tumor (Mixed-adenocarcinoma-NET). Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) is a rare disease. Based on the available data, neuroendocrine component has a highly aggressive biological behaviour represented by a low-diﬀerentiated neuroendocrine tumor in the majority of MiNENs cases. The treatment is based on the principles of neuroendocrine tumour therapy. The foregoing shows that it is not possible to provide precise epidemiological data, prognosis and approve treatment strategies.