The Origins of Merkel Cell Carcinoma: Defining Paths to the Neuroendocrine Phenotype.

Two recent reports leverage careful genomic analysis to show that human Merkel cell carcinomas (MCCs) arising from squamous cell carcinoma in situ bear hallmarks of genetic relatedness, suggesting that a subset of MCCs can arise from pre-existing intraepithelial keratinocytic proliferations in human skin. This has important implications for our understanding of cells of origin and the diverse drivers of MCC formation.