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Merkel cell carcinoma update: the case for two tumours
Author(s) -
Nirenberg A.,
Steinman H.,
Dixon J.,
Dixon A.
Publication year - 2020
Publication title -
journal of the european academy of dermatology and venereology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.655
H-Index - 107
eISSN - 1468-3083
pISSN - 0926-9959
DOI - 10.1111/jdv.16158
Subject(s) - merkel cell carcinoma , merkel cell polyomavirus , merkel cell , medicine , skin cancer , carcinoma , incidence (geometry) , pathology , oncology , cancer , dermatology , cancer research , physics , optics
Abstract Merkel cell carcinoma ( MCC ) is an aggressive tumour with neuroendocrine differentiation. Clinically significant differences within the entity we know as MCC are apparent. This review aims to evaluate the evidence for differences in tumours within Merkel cell carcinoma and to stratify these. A literature search of research pertaining to various characteristics MCC was undertaken from 1972, when Merkel cell carcinoma was first described, to 2018, using PubMed and similar search engines. A total of 41 papers were analysed, including clinical trials, laboratory‐based research and reviews. A proportion of MCC has Merkel cell polyomavirus genome integrated ( MCP yV+) while others do not (MCPyV−). Both types have a different mutation burden. MCP yV+ tumours are likely true neuroendocrine carcinomas, with a dermal origin, probably from fibroblasts which have been transformed by integration of the viral genome. MCP yV−tumours are likely derived from either keratinocytes or epidermal stem cells, are probably squamous cell carcinomas with neuroendocrine differentiation, and are related to sun damage. Prognostic factors (apart from tumour stage) include the MCP yV status, with MCP yV+ tumours having a better prognosis. P63 expression confers a worse prognosis in most studies. CD 8+ lymphocytes play an important role, providing a possible target for PD 1/ PD ‐L1 blockade treatment. The incidence of MCC varies from country to country. Countries such as Australia have a high rate and a far greater proportion of MCP yV− tumours than places such as the United Kingdom. MCC doubtlessly encompasses two tumours. The two tumours have demonstrated differences in prognosis and management. One is a neuroendocrine carcinoma related to MCP yV integration likely derived from fibroblasts, and the other is a UV ‐related squamous cell carcinoma with neuroendocrine differentiation, presumptively derived from either keratinocytes or epidermal stem cells. We propose naming the former Merkel type sarcoma and the latter squamous cell carcinoma, Merkel type.