Merkel Cell Carcinoma of the Buccal Mucosa and Lower Lip

Abstract

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.

MicroRNA dysregulations in Merkel cell carcinoma: Molecular mechanisms and clinical applications

“…MCC was first described in 1972 by Cyril Toker as a trabecular skin carcinoma. Later, the tumor name was modified to MCC given the similarity in appearance and ultrastructure between tumor cells and Merkel cells, the mechanoreceptors of the basal epidermal layer of the skin 20 . Both MCC subtypes are characterized by different stages, including localized, regional, and distant metastasis 21 .…”

Merkel cell carcinoma of the oral cavity: A case report

“…The estimated three-year survival of MCC has been reported as low as 50%. [4] In conclusion, mucosal MCC is an uncommon and aggressive neuroendocrine neoplasm with a high risk for recurrence and distant metastasis. It should be considered in the differential diagnosis of head and neck mucosal lesions.…”

“…At time of diagnosis most lesions have metastasized to the regional lymph nodes. [4] Histopathologically, the tumor shows small, round to ovoid primitive looking cells with a strong acidophilic staining with a salt-andpepper-like nuclei and inconspicuous nucleoli. The IHC staining is an important ancillary test for diagnosing MCC.…”

“…[3] Primary MCCs of the oral cavity are extremely rare, with only 26 cases reported in the literature to date. [4] In this article, we present an oral MCC case and discuss its histological and immunohistochemical features in the light of literature data.…”

Merkel Cell Carcinoma of the Mandible: A Case of Spontaneous Acceleration of the Growth

“…In 2008, a cohort study following 195 patients found 88% of MCCs were nontender [9]. Merkel cell carcinoma of the mandibular or submandibular glad is extremely rare and there are only a handful of case reports on this topic, although MCC is well known to affect the skin of the head and neck [10,11].…”