This subtype of MCC, which was found to be more prevalent in certain geographic regions with high levels of sun exposure [29,30], arises from UV-induced DNA damages and displays characteristic oncogenetic features: high TMB, inactivation of tumor suppressor genes (e.g., Rb1 and TP53) [31,32], and high frequency of mutated NOTCH1 and FAT1. This evidence concerns the gene RB1 and Merkel cell skin cancer.