Islam Mohammed N, Chehal Hardeep, Smith Molly Housley, Islam Sarah, Bhattacharyya Indraneel
Department of Oral and Maxillofacial Surgery and Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL, 32610, USA.
Department of Oral Diagnostic Sciences, Creighton University, School of Dentistry, Omaha, NE, USA.
Head Neck Pathol. 2018 Jun;12(2):279-285. doi: 10.1007/s12105-017-0859-1. Epub 2017 Oct 4.
Merkel cell carcinoma (MCC) is an uncommon relatively aggressive neuroendocrine dermal neoplasm first described in 1972 as a tumor of the sun exposed skin. Although most MCC affect the skin of the head and neck, rare primarily oral mucosal cases have been documented. Merkel cells are nondendritic neuroendocrine cells that are found not only in the skin but also the oral mucosa and give rise to MCC. Neuroendocrine cells may be found as aggregates in organs or as diffuse or isolated cells within organs and their epithelial lining. They contain peptide hormones and biogenic amines and occur in two forms: dendritic, which are not associated with nerve fibers and non-dendritic, which are associated with nerve fibers. Merkel cells as well as MCC express simple epithelium-type Cytokeratins (8, 18, 19, 20), neurosecretory substances; chromogranin A, synaptophysin, neuron-specific enolase (NSE), adhesion molecules, and villin (intermediate filament). Though weakly, they also express neural markers such as S-100 protein. Cytokeratin 20, and Cluster of differentiation 56, are the two key diagnostic markers for Merkel cells and MCC. Etiology includes UV radiation, the recently described Merkel cell polyomavirus, and long term systemic immunosuppression. The cutaneous and mucosal variants of MCC are considered aggressive tumors with a high risk for local recurrence and metastasis and should be considered in the differential diagnosis of head and neck mucosal lesions. We present two cases of primary Merkel cell carcinoma, one on the buccal mucosa and the other on the lower lip, and discuss the salient histologic, immunohistochemical and clinical features.
默克尔细胞癌（MCC）是一种罕见的、相对侵袭性的神经内分泌性皮肤肿瘤，于1972年首次被描述为一种暴露于阳光下皮肤的肿瘤。尽管大多数MCC发生于头颈部皮肤，但也有罕见的原发性口腔黏膜病例的记录。默克尔细胞是一种非树突状神经内分泌细胞，不仅存在于皮肤中，也存在于口腔黏膜中，并可引发MCC。神经内分泌细胞可作为器官中的聚集物存在，也可作为器官及其上皮内衬中的弥漫性或孤立性细胞存在。它们含有肽类激素和生物胺，有两种形式：与神经纤维无关的树突状和与神经纤维相关的非树突状。默克尔细胞以及MCC表达简单上皮型细胞角蛋白（8、18、19、20）、神经分泌物质；嗜铬粒蛋白A、突触素、神经元特异性烯醇化酶（NSE）、黏附分子和绒毛蛋白（中间丝）。尽管表达较弱，但它们也表达神经标志物，如S-100蛋白。细胞角蛋白20和分化簇56是默克尔细胞和MCC的两个关键诊断标志物。病因包括紫外线辐射、最近发现的默克尔细胞多瘤病毒和长期的全身免疫抑制。MCC的皮肤和黏膜变体被认为是具有局部复发和转移高风险的侵袭性肿瘤，在头颈部黏膜病变的鉴别诊断中应予以考虑。我们报告两例原发性默克尔细胞癌，一例发生于颊黏膜，另一例发生于下唇，并讨论其显著的组织学、免疫组化和临床特征。
