KRT20 and Merkel cell skin cancer: Commonly employed IHC stains used in the diagnosis of CK20‐negative MCC include neurofilament, chromogranin, synaptophysin, CD56, neuron‐specific enolase (NSE), Merkel cell polyomavirus large T antigen, special AT‐rich sequence‐binding Protein 2 (SATB2), paired Box 5 (PAX5), cytokeratin CAM 5.2, and AE1/AE3 [7, 8, 10–13].