Primary Neuroendocrine Carcinoma Combined with Squamous Cell Carcinoma of the Soft Palate: A Case Report and Review of Literature

Abstract

Background: Neuroendocrine carcinomas (NECs) are rare neoplasms that widely occur in various organs. They are heterogeneous and vary from low to high grade malignant. NEC presenting with a squamous cell carcinoma (SCC) component is referred to as a composite tumor. Thus far, few cases of this composite tumor in the oral cavity have been reported in the literature; thus, the histogenesis remains unclear. ase Presentation: We encountered a rare case of a primary NEC combined with SCC, occurring at the soft palate in a 59-year-old man. A resected specimen of the tumor was composed of two components: NEC and SCC. The NEC area contained small round to oval atypical cells arranged in nests with a glandular-like-pattern, hyperchromatic molded nuclei, a high nuclear-to-cytoplasmic ratio, and a scant eosinophilic cytoplasm. The SCC area was composed of non-keratotic, dysplastic oval to spindle-shaped squamous cells with indistinct cell borders and large nuclei that were hyperchromatic and pleomorphic. Immunohistochemically, the tumor cells of the NEC component were positive for chromagranin A, synaptophysin, CD56, and p16, whereas those of the SCC component were positive for 34βE12, p63, and p16. Conclusion: In consideration of the morphological and immunohistochemical results, the final diagnosis was a primary NEC combined with SCC of the soft palate.