Polyomavirus-positive Merkel cell carcinoma derived from a trichoblastoma suggests an epithelial origin of Merkel cell carcinoma

To assess the lineage of origin of MCPyV-positive MCC, genetic analysis of a rare tumor combining benign trichoblastoma and MCPyV-positive MCC was conducted by massive parallel sequencing. Although MCPyV was found to be integrated in only the MCC part, six somatic mutations were shared by both tumor components. The mutational overlap between trichoblastoma and MCPyV-positive MCC part of the combined tumor implies that MCPyV integration occurred in an epithelial tumor cell prior to MCC development. Therefore, it appears likely that cells of the epithelial lineage are the origin of MCPyV-positive MCCEGA study EGAS00001003784