Immunohistochemical markers include positive results for cytokeratin 7, gross cystic disease fluid protein-15 (GCDFP-15), and CEA and negative results for P63 and SOX10 [1]. The immunohistochemical marker SOX10 is important in the evaluation of an EMPD biopsy as it helps differentiate it from other neoplasms with similar histopathological features, particularly melanoma in situ or metastatic melanoma. The gene discussed is SOX10; the disease is extramammary Paget disease.