Immunohistochemistry may be useful in discriminating primary EMPD (HER-2/neu positive, CDX2 negative) from EMPD secondary to anorectal adenocarcinoma (HER-2/neu negative, CDX2 positive), but not EMPD secondary to urothelial or prostatic malignancy [5]. This evidence concerns the gene CDX2 and extramammary Paget disease.