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

Mixed neuroendocrine-nonneuroendocrine (MiNEN) neoplasms in the head and neck are exceptionally rare biphasic tumors with unclear pathogenesis and an aggressive clinical behavior. This is the first reported case of an oropharyngeal MiNEN with the nonneuroendocrine component being an HPV-associated adenocarcinoma. The tumor arose in a 56 year-old male with history of long-term cigarette smoking and was composed of an adenocarcinoma intermixed with a small cell neuroendocrine carcinoma. P16 immunohistochemical stain and HPV16/18 in-situ hybridization were strongly and diffusely expressed in both components.