Primary ectopic breast cancer of the vulva, treated with local excision of the vulva and sentinel lymph node biopsy: a case report

Primary breast cancer fairly infrequently occurs in ectopic breast tissue, and primary ectopic breast cancer of the vulva is particularly rare. Only 26 cases have been published in the English-language literature, and there has been no report of primary breast carcinoma of the vulva in Japan. We report a rare case of primary ectopic breast cancer of the vulva that was treated with local excision of the vulva and sentinel lymph node biopsy (SLNB). The patient was a 72-year-old woman who had noticed a right vulvar tumor 10 years earlier. The tumor was excised by the Department of Plastic Surgery of our hospital. The histology of the vulvar tumor revealed an invasive ductal carcinoma of the breast, and immunohistochemical staining of the vulvar specimen showed the tumor cells to be 100% estrogen-receptor-positive and 100% progesterone-receptor-positive. All margins of resection were positive for neoplastic involvement. An additional local excision of the vulva and right inguinal SLNB were performed in our department. The intraoperative frozen section was negative for metastasis, and lymph node dissection was not performed. The final pathology was negative for residual disease, and a partially normal ductal component was present. Adjuvant hormonal therapy with an aromatase inhibitor was indicated post-operatively. The patient was asymptomatic and free of detectable disease at a 6-month follow-up. Due to the rarity of this diagnosis, there are no established guidelines for treatment. Although cases in which SLNB was performed are rare, we consider SLNB to be an effective alternative to inguinal node dissection for ectopic primary breast cancer of the vulva.