Neuroendocrine carcinoma of the oral cavity: a case report and review of the literature.

Neuroendocrine (NE) carcinoma is a rare disease originating from the NE cell system, which is considered to be the third division of the nervous system. Based on their biological characteristics, NE carcinomas are classified into three subtypes: well-differentiated NE carcinoma (typical carcinoid tumor), moderately differentiated NE carcinoma (atypical carcinoid tumor), and poorly differentiated carcinoma (small cell carcinoma). Among the primary tumors, the propensity for disease to spread to the oral region varies. Although metastatic oral disease is rare, dentists should be aware of such a possibility, particularly when examining patients with a known history of malignancy. This case report describes a patient with an unknown primary NE malignancy that led to metastatic lesions in both the liver and mandibular soft tissues.