A Case of Accessory Breast Cancer Arising on the Left Anterior Chest Wall

Abstract

Accessory breast cancer is rare, and most cases arise in the axial breast tissue. Accessory breast cancer arising on the caudal side of the inframammary fold is extremely rare. Herein, we report a case of accessory breast cancer on the caudal side of the inframammary fold on the anterior chest wall. A 48-year-old woman presented to our hospital with a tumor on the caudal side of the inframammary fold on the anterior chest wall. The supernumerary nipple existed on the milk line on the inframammary fold. The tumor was located on the caudal side of the supernumerary nipple. Excisional biopsy of the tumor revealed that the tumor was histologically similar to invasive ductal carcinoma in the breasts. Imaging studies did not reveal any tumors in the breasts. Therefore, the patient was diagnosed with accessory breast cancer. Since the surgical margin of the resected tumor was suspected to be positive, the patient underwent additional resection, followed by administration of tamoxifen as adjuvant therapy. She is currently alive 2 years and 6 months after the surgery without recurrence. No standard treatment has been established for accessory breast cancer. Therefore, it is necessary to review more cases to establish standard treatments.