Mucinous adenocarcinoma with neuroendocrine differentiation of the mandibular ramus: report of a case

A rare case of mucinous adenocarcinoma with neuroendocrine differentiation of the mandibular ramus is presented. The patient, an 80‐year‐old man, was referred to our hospital with chief complaint of swelling and pain in the left buccal mucosa. CT and MRI examination showed an osteolytic tumor mass occupying the upper region of the left mandibular ramus. Macroscopically, the excised tumor was a relatively well‐defined, solid mass with diffuse bone resorption, measuring 3 cm × 3.2 cm × 3 cm. Microscopical examination showed that the tumor forming glandular structures with abundant mucous production and high cellular atypia. Immunohistochemical studies demonstrated the positive reactivities for pan‐keratin, cytokeratin 7, vimentin,α‐amylase, α‐smooth muscle actin, neuron‐specific enolase, glial fibrillary acid protein, calcitonin, and somatostatin in tumor cells. These findings suggested that the tumor was originated from heterotopic or misplaced salivary gland in the mandible.