Accessory Breast Apocrine Carcinoma: Report of a Rare Case.

Axillary apocrine carcinoma may arise from cutaneous adnexal glands or breast tissue, including accessory breast tissue. Accessory breast carcinoma is rare, and apocrine carcinoma represents an uncommon histologic subtype of breast cancer. For accessory breast carcinoma, wide local excision and lymph node dissection is generally recommended. Postoperative therapy, including endocrine therapy, is considered following treatment strategies for breast cancer. We report an extremely rare case of accessory breast apocrine carcinoma (ABAC). To the best of our knowledge, this is the first case documented in the English-language literature. A 57-year-old woman presented with an enlarged cutaneous tumor in the right axilla. Initial excision revealed apocrine carcinoma arising from the cutaneous adnexal glands or accessory breast tissue. Imaging demonstrated axillary lymph node metastasis, and the patient subsequently underwent wide local excision with axillary lymph node dissection. Histopathological examination confirmed accessory breast tissue adjacent to the carcinoma, leading to a diagnosis of ABAC. The tumor showed a triple-negative phenotype, and postoperative radiation therapy was administered. At the five-month follow-up, no recurrence or lymphedema was observed.