Abstract
Extra-mammary Paget disease (E-MPD) is a rare primary cutaneous carcinoma of uncertain etiology (apocrine, anogenital mammary-like glands) commonly arising in the vulva, while mammary Paget's disease (MPD) is a frequent manifestation of intra-epidermal dissemination of an underlying invasive breast carcinoma. The post-surgical recurrence rate in E-MPD is 20-40%, and metastatic E-MPD has a poor survival rate. While there is no standard systemic treatment, cases of E-MPD with amplified ERBB2/HER2 have been successfully treated with Trastuzumab, alone or in combinations. However, HER2 amplification is overall rare in E-MPD, and most cases are triple (ER/PR/HER2) negative E-MPD.