Neuroectodermal Neoplasms of the Head and Neck with Emphasis on Neuroendocrine Carcinomas

Abstract

Tumors exhibiting neuroectodermal differentiation occur throughout the body, and the diverse tissues of the head and neck give rise to a wide assortment of these neoplasms. Neuroectodermal neoplasms may be divided into lesions showing primarily epithelial differentiation (Group I, neuroendocrine carcinomas) and a more diverse group (Group II) of nonepithelial neoplasms. This article reviews these neuroectodermal tumors of the head and neck with emphasis on the neuroendocrine carcinomas and their nomenclature. The author believes that with regard to Group I tumors, the older terminology of carcinoid, atypical carcinoid, and small cell carcinoma should be replaced by subclassifications of well-differentiated, moderately differentiated, and poorly differentiated neuroendocrine carcinoma. The latter category should be further subdivided into small cell and large cell variants. Neuroendocrine carcinomas, particularly the moderately differentiated subtype, are often underdiagnosed in the head and neck region. In the larynx, these tumors are the most common form of nonsquamous carcinoma. Poorly differentiated neuroendocrine carcinoma of small cell type is most common in the salivary glands but can occur elsewhere in the region. The large cell subtype of poorly differentiated neuroendocrine carcinoma has not been well documented in this region. However, the most likely candidate for this tumor category is the so-called sinonasal undifferentiated carcinoma. Group II tumors discussed include olfactory neuroblastoma, malignant melanoma, and Ewing's sarcoma. In addition, differential diagnostic problems related to Group I and II tumors are reviewed in detail. This article reviews and updates our understanding of neuroectodermal neoplasms arising in the head and neck. The focus is on tumors that exclusively involve this region or show a strong predilection to occur here.

Thyroid transcription factor-1, but not p53, is helpful in distinguishing moderately differentiated neuroendocrine carcinoma of the larynx from medullary carcinoma of the thyroid

“…Although the morphologic findings of these tumors have not varied, the nomenclature of laryngeal neuroendocrine neoplasms has changed since the time that they were first recognized. [2][3][4]6,17,18 In 1993, the World Health Organization (WHO) subdivided laryngeal neuroendocrine tumors into carcinoid, atypical carcinoid and small cell carcinoma. 17 More recently, it has been suggested 2 that the following nomenclature would more accurately represent morphologic and biologic differences between laryngeal neuroendocrine neoplasms: well-differentiated neuroendocrine carcinoma (typical carcinoid), moderately differentiated neuroendocrine carcinoma (atypical carcinoid), poorly differentiated neuroendocrine carcinoma-small cell type and poorly differentiated neuroendocrine carcinoma-large cell type.…”

“…1,2 Moderately differentiated neuroendocrine carcinomas of the larynx and medullary carcinomas of the thyroid demonstrate morphological overlap, and can be microscopically indistinguishable, particularly when presenting as a metastasis. Currently, serum calcitonin is the only objective means for distinguishing primary moderately differentiated neuroendocrine carcinoma of the larynx from metastatic medullary carcinoma, as calcitonin immunohistochemistry is reportedly positive in both tumors.…”

Management of nonsinonasal neuroendocrine carcinomas of the head and neck

“…Two tumors were hybrids, with a component of squamous cell carcinoma within an extensive background of small cell carcinoma. Tumors that potentially could be confused 8 with NSNEC (including paraganglioma, 9 medullary carcinoma, 10 basaloid squamous cell carcinoma, 11 melanoma, 12 pituitary adenoma/carcinoma, 13 or Merkel cell carcinoma 14 ) were excluded from the current analysis.…”

Olfactory Neuroblastoma: A Case Report

“…Occasionally, the dendritic processes of these cells may be noted within the tumor lobules. In high grade tumors, the sustentacular cells may be sparse or absent [14]. Of note, approximately 30 % of ONBs will exhibit focal staining for cytokeratins, including low molecular weight cytokeratins (Cam 5.2) [5,14].…”

“…In high grade tumors, the sustentacular cells may be sparse or absent [14]. Of note, approximately 30 % of ONBs will exhibit focal staining for cytokeratins, including low molecular weight cytokeratins (Cam 5.2) [5,14]. This staining pattern may occur in areas of obvious divergent glandular differentiation; however, the cytokeratin immunoreactivity is never diffuse throughout the tumor cell population.…”