KRT20 and Merkel cell skin cancer: Cytokeratin 20 (CK20) and neuroendocrine markers such as chromogranin A, synaptophysin, CD56, neuron-specific enolase, and neurofilaments are expressed in MCC.3, 14, 21 Paranuclear dot-like immunopositivity for CK20 is highly suggestive, whereas the neuroendocrine markers are non-specific.3