Accessory breast cancer: a case report and review of the Japanese literature.

The case of a 31-year-old woman with accessory breast cancer in the left axilla is described. She had noticed a swelling in the left axilla during her three pregnancies. The preoperative diagnosis of accessory breast cancer was made on the basis of ultrasound-guided fine-needle aspiration biopsy (US-FNAB) and clinical history. She was treated by wide local resection and regional lymph node dissection. Although cancer originating from accessory breast tissue has been reported very rarely, knowledge of this disorder may facilitate the correct diagnosis of axillary tumors. US-FNAB is a useful and simple technique for the tissue diagnosis of axillary tumors.