[A Case Report of Accessory Breast Cancer in the Right Axillary Region].

An 80-year-old woman visited a previous hospital complaining of a lump in the right axillary region. Because it was suspected of accessory breast cancer from the findings of image inspection, she was referred for surgery. Based on mammography and ultrasonography, both bilateral mammary glands were reported normal, but an irregular mass was found in the right axillary region. Resection biopsy showed adenocarcinoma like invasive ductal carcinoma. In addition, ER and PgR were positive. With a preoperative diagnosis of accessory breast cancer, she underwent wide local resection of the right axillary region with lymph-node dissection(Level Ⅰ), and local pedicle flap formation. Histopathological findings revealed that the tumor was composed of invasive ductal carcinoma. The center of tumor was consisted of ductal tissue discontinuous with normal mammary gland. So, a diagnosis of accessory breast cancer in the right axillary region was confirmed. She is currently in recurrence-free survival. Accessory breast cancer is relatively rare. We report a case of accessory breast cancer in the axillary region with some review of the literature.