Abstract
BACKGROUND: Breast cancer is the most common malignancy among women worldwide. In men, cases of breast cancer are few and account for less than 1% of all cases of breast cancer. Majority of male breast cancer is hormone receptor-positive. The incidence of male breast cancer derived from axillary accessory breast is very low. Here we report a case of male triple negative axillary accessory breast cancer. CASE DESCRIPTION: We present a case of male triple negative axillary accessory breast cancer in a 67-year-old man, which progressively increased in size through a period of 1 year. Ultrasound examination showed a 31 mm × 17 mm mass in the right axillary tail region with some accessory breast tissue around. We performed right accessory breast resection and right axillary lymph nodes dissection. Postoperative pathological analysis revealed right accessory breast invasive ductal carcinoma with apocrine metaplasia. The tumor size was 3.5 cm × 3.3 cm. In addition, 5 metastatic lymph nodes were seen in 27 axillary lymph nodes. Immunohistochemistry showed estrogen-receptor (ER) (-), progesterone-receptor (PR) (-), human epidermal growth factor receptor 2 (HER2) (2+). Fluorescence in situ hybridization (FISH) test obtained a negative result. The patient was treated with adjuvant chemotherapy and radiotherapy. Until now, no obvious signs of recurrence or metastasis have been observed during regular follow-ups. CONCLUSIONS: Male triple negative axillary accessory breast cancer is rare. Treatment of male triple negative axillary accessory breast cancer is similar to that of women. Most patients undergo surgery and adjuvant chemotherapy.