A Rare Presentation of Primary Breast Carcinoma in the Vulva: A Case Report and Literature Review.

Background Mammary gland carcinoma arising from ectopic mammary tissue in the vulva is an extremely rare occurrence with only 28 cases reported in the literature and carrying an uncertain prognosis. Case Presentation This report describes the case of a 58 year old woman presenting with a 1.5 cm lesion on the transition between the right labia minora and majora. The patient was treated with wide vulvar resection and right inguinal lymphadenectomy. Pathology review revealed a 1.2cm, grade 3, invasive carcinoma, positive for estrogen receptor and human epidermal growth factor receptor 2, and tumor characteristics indicating a mammary gland carcinoma. The patient is being treated with adjuvant with anthracycline-taxane chemotherapy, trastuzumab, and hormonal therapy. Conclusions Mammary gland carcinoma of ectopic tissue in the vulva is an extremely rare occurrence. As such, clinicians should carefully consider differential diagnoses, such as primary or metastatic breast carcinoma, Bartholin’s gland carcinoma, invasive Paget’s disease, primary carcinoma of the major and minor vestibular glands, and carcinoma originating from the sweat gland. Surgical procedures generally include a radical vulvectomy or wide local excision with lymph node assessment, and adjuvant treatment with radiation, chemotherapy, or hormonal therapy. A tailored therapy guided by the tumor’s histological and molecular characteristics should be considered for these patients.