Neuroendocrine Tumors of the Head and Neck: A Selected Review with Emphasis on Terminology.

Virtually every variant of neuroendocrine neoplasia can occur, at least rarely, in the head and neck region. This review focuses on the terminology surrounding neuroendocrine carcinomas of the larynx and their distinction from morphologically similar but biologically distinctive neoplasms. It is suggested that rare typical laryngeal carcinoids be labeled as such. There is little evidence that these lesions are part of a morphologic continuum. In contrast, more common "carcinoid-like" carcinomas, previously referred to as "atypical carcinoids" are more appropriately labeled as "moderately differentiated neuroendocrine carcinomas." These neoplasms should, in turn, be distinguished from "small cell neuroendocrine carcinomas," although these latter two neoplasms do represent a morphologic and behavioral spectrum. Light microscopic and immunohistochemical features distinguishing neuroendocrine carcinomas of the larynx from paraganglioma, metastatic medullary carcinoma, malignant melanoma, and basaloid squamous cell carcinoma are presented. The second portion of this review outlines the clinicopathologic features of two head and neck neoplasms exhibiting varying degrees of neuroendocrine differentiation. Olfactory neuroblastomas have well-developed neuroendocrine differentiation, almost invariably arise from the olfactory mucosa, typically exhibit low-grade cytologic features, and may have protracted clinical course with an approximately 50% overall 5-yr survival. In contrast, sinonasal undifferentiated carcinoma is a microscopically high-grade neoplasm with minimal, abortive neuroendocrine features, a highly aggressive clinical course, and virtually 100% mortality. They can arise throughout the sinonasal region.