Detection of Merkel cell polyomavirus in tumor cells and peritumoral lymphocytes of non-melanoma skin cancer by Immunohistochemistry

Merkel cell polyomavirus (MCPyV) is an oncogenic virus etiologically related to Merkel cell carcinoma and has been found in association with non-melanoma skin cancer (NMSC), with controversial results. Little is known about the role or influence of MCPyV in the development of these tumors and its prevalence in various populations. To assess the prevalence of MCPyV`s Large T Antigen and its DNA in cases of NMSC, nested-PCR and immunohistochemistry (IHC) were performed on 103 samples of NMSC from 91 patients and these results were correlated with epidemiological and demographical data. A total of 44 (42,7%) tumors were positive for the virus via PCR, 34 (77,3%) in the BCC group, 6 (13,6%) in the cSCC, 3 (6,8%) for Bowen’s disease and 1 (2,3%) for keratoacanthoma. The IHC results shows a positivity of 15 (14,6%), 7 cases of positivity in the tumor, 8 in the peri-tumoral infiltrate and 3 in both, and with 11 (73,0%) of positivity in the BCC group, 3 (20,0%) in the cSCC, 0 (0,0%) for Bowen’s disease and 1 (7,0%) for keratoacanthoma. Despite the frequent detection of MCPyV DNA and large T antigen in NMSC, its possible role in the development of NMSC is unlikely.