Background: About 10% of patients with Merkel cell carcinoma (MCC) suffer from an associated squamous cell carcinoma (SCC). In European patients, Merkel cell polyomavirus (MCPyV) is detectable in 60%–88% of the MCC tumors. In combined lesions, MCPyV was not detectable so far.
Methods: We investigated 2 combined tumors of MCC and SCC for the presence of MCPyV and human papillomavirus (HPV) by polymerase chain reaction and immunohistochemistry.
Results: In both lesions, MCPyV DNA was found, and in 1 case, HPV DNA was also detected. This is the first report of a coinfection with HPV and MCPyV in combined MCC–SCC tumors.
Conclusions: The results underline the hypothesis of cocancerogenesis of 2 oncogenic viruses in nonmelanoma skin cancer. Technical reasons and a low viral copy number of MCPyV hampering immunohistochemical detection may be responsible for the negative results in the literature.
*Department of Dermatology, Venereology and Allergology, Klinikum Hildesheim GmbH, Hildesheim, Germany
†Kempf and Pfaltz Histological Diagnostics, Research Unit, Zurich, Switzerland
‡Cantonal Institute of Pathology Liestal, Liestal, Switzerland
§Department of Pathology, University Hospital Germans Trias i Pujol, Badalona, Spain.
The authors declare no conflicts of interest.
Reprints: Christina Mitteldorf, MD, Department of Dermatology, Venerology and Allergology, Klinikum Hildesheim GmbH, Weinberg 1, D-31134 Hildesheim, Germany (e-mail: firstname.lastname@example.org).