KRT20 and Merkel cell skin cancer: Because the malignancies shared neuroendocrine markers with Merkel cells, such as cytokeratin-20 (CK20) and neuron-specific enolase (NSE), the disease was named Merkel cell carcinoma (De Wolff-Peeters et al., 1980; Gu et al., 1983; Moll et al., 1992).