KRT20 and Merkel cell skin cancer: An immunohistochemical study using specific staining techniques confirmed the diagnosis of MCC and, more specifically, cytokeratin 20 (CK20) expression, which is often evident as a paranuclear globule (Fig. 2); synaptophysin (Fig. 3); CD99; neuron-specific enolase; and negativity of the melanocytic and muscular markers.