TP53 and Merkel cell skin cancer: Previously, single institution and small case series have described smaller sets of genomic analysis from patients with MCC.13,14,15,16,17,18,19 A review by Erstad et al13 noted that the most common variant genes in patients with MCC included RB (a restrictor of the cell cycle), TP53, and PIK3CA. In a small set of tumors, Harms et al14 showed that MCPyV-negative tumors were TMB-H and had an ultraviolet signature with additional oncogenic alterations in HRAS, PRUNE2, and NOTCH family genes, whereas MCPyV-positive tumors were TMB-L and had no ultraviolet signature.