MUC1 and skin basal cell carcinoma: The differential diagnosis of extraocular SC includes basal cell carcinoma (BCC), SCC, amelanotic melanoma, Merkel cell carcinoma, and cutaneous lymphoma.1, 3 The immunohistochemical use of markers for BerEP4, EMA (negative in BCC), AE1 and AE3 (negative in melanoma, lymphomas), adipophilin (negative in SCC, Merkel), p53 and Ki-67, will aid in the diagnosis and prognosis.1, 2, 3, 4 The treatment comprises surgical resection with a 1-cm margin or the use of the micrographic surgical technique.2