Oropharyngeal Mixed Neuroendocrine-Nonneuroendocrine Neoplasm (MiNEN): A Case Report and Literature Review.

Primary mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN) of the head and neck region is a rare biphasic tumor with an aggressive biological behavior. This report highlights an additional case of oropharyngeal MiNEN in a 46-year-old male patient with a previous long-term smoking history. Histologic evaluation revealed a biphasic tumor infiltrating the lamina propria. The first component consisted of a classic keratinizing squamous cell carcinoma. The second component consisted of small-to-intermediate sized cells with neuroendocrine features. Synaptophysin and CD56 immunohistochemical stains confirmed neuroendocrine lineage in this component. The presence of two morphological components with neuroendocrine and nonneuroendocrine features on histologic assessment should alert the pathologist to consider a MiNEN in their case work-up.