MUC1 and melanoma: Immunohistochemical staining to confirm this diagnosis demonstrated that the tumor cells were positive for pan melanoma, S-100 protein, Vimentin, and HMB45 (melanoma marker) (Figure 2), and were negative for cytokeratin (CK), epithelial membrane antigen (EMA), chromaffin A (CgA), synaptophysin (Syn), high molecular weight cytokeratin, small cell lung cancer (SCLC) , Desmin, smooth muscle actin (SM-actin), neuron specific enolase (NSE), leukocyte common antigen (LCA), and CD34.