As ATOH1 is expressed in Merkel cells and most Merkel cell carcinomas (MCCs),34 we checked whether ATOH1 CDXs were, in fact, derived from CTCs from misdiagnosed MCC primary tumors characterized by oncogenic Merkel cell polyoma virus (MCPyV) (found in 80% of cases).35 The gene discussed is ATOH1; the disease is Merkel cell skin cancer.