How to differentiate mucinous eccrine carcinoma from cutaneous metastasis of breast carcinoma?

ccrine skin tumors are rare and represent only 0,05% of all cutaneaous neoplasms. They represent a pitfall especially with cutaneous metastases of carcinoma which are more frequent. We report the case of a 60-year-old woman presented with a frontal scalp mass whose histologic and immunohistochemical features concluded initially to a cutaneous metastasis of breast carcinoma. The diagnosis was reviewed because of the absence of a breast lesion. The final diagnosis was primary sweet gland carcinoma. Histologic distinction between cutaneous metastatic breast carcinoma and primary cutaneous adnexal neoplasms can be very challenging or even impossible. This case illustrates this difficulty and puts emphasis on the necessity of keeping in mind the distinctive features between these two entities