Given that majority of male axillary accessory breast degenerate, there are few cases of male axillary accessory breast (6). The incidence of male axillary accessory breast cancer is very low. For this reason, no large-scale prospective randomized clinical trials have been conducted to determine effective therapy for this condition (7). Currently, male axillary accessory breast cancer is treated similar to female breast cancer (8).
Operable male axillary accessory breast cancer is comprehensively treated with surgery (8). In general, mastectomy with sentinel lymph nodes biopsy is performed (8, 9). For patients suspected with axillary lymph node metastasis, axillary lymph nodes dissection can be performed directly instead of sentinel lymph node biopsy. Compelling evidence indicates that breast conserving surgery is safe and feasible for male breast cancer (10–12). However, in clinical practice, male breast cancer occurs near the nipple in most cases and majority of patients with male breast cancer do not have a strong need undergo a breast-conserving surgery. Most patients with male breast cancer receiving treatment in our department agreed to undergo breast resection. In the present case, with the clinical suspicion of axillary lymph nodes metastasis, the patient underwent accessory breast resection and axillary lymph node dissection.
The application of chemotherapy and radiotherapy in male patients with axillary accessory breast cancer is similar to that of female patients with breast cancer (8, 12). The prognosis of patients with male breast cancer is worse compared to female patients with breast cancer. In our clinical practice, most male patients with breast cancer are given chemotherapy containing anthracycline or paclitaxel. We often assess the prognosis of patients using oncotype DX and other gene prognostic models to decide the appropriate chemotherapy (13, 14). The adjuvant radiotherapy applied to male breast cancer is similar to that used for female patients with breast cancer. Adjuvant radiotherapy is recommended for patients with axillary lymph nodes metastasis or undergoing breast conserving surgery. Postoperative radiotherapy is also recommended for patients with tumors larger than 5cm. In our case, the patient was diagnosed with T2N2M0, IIIA stage male triple negative axillary accessory breast cancer. Ki-67 was 30%. He received 8 cycles of chemotherapy comprising anthracycline and paclitaxel. We recommended a high dosing of chemotherapy for every 2 weeks but the patient refused due to poor tolerance. We adjusted the cycle of chemotherapy to every 3 weeks. With 5 out of 27 lymph nodes metastasis, the patient received adjuvant radiotherapy after chemotherapy.
Pathological examination confirmed invasive ductal carcinoma with apocrine metaplasia. Less than 90% of the cancer cells showed morphological and immunohistochemical characteristics of apocrine gland cells. Hence, the patient was diagnosed with invasive ductal carcinoma with apocrine metaplasia instead of apocrine carcinoma (15). The cancer was estrogen receptor negative and progesterone receptor negative, possibly due to the apocrine metaplasia, which is rare in male breast cancer. This is a rare case of male triple negative axillary accessory breast cancer.