Male Accessory Breast Cancer Successfully Treated With Single-Agent Trastuzumab: A Case Report

• Published in: American journal of men's health 2023-05, Vol.17 (3), p.15579883231171010-15579883231171010
• Main Authors: Ji, Wencai, Guo, Wenbin
• Format: Article
• Language: English
• Subjects: Aged; Breast cancer; Breast Neoplasms; Breast Neoplasms, Male - drug therapy; Breast Neoplasms, Male - surgery; Case Report; Case reports; Humans; Male; Trastuzumab - therapeutic use
• ISSN: 1557-9883; 1557-9891
• DOI: 10.1177/15579883231171010

Male accessory breast cancer is an extremely rare tumor. There is no report about its monotherapy and subsequent outcome prior to 2022. The current study presents the case of a 76-year-old male patient with a hard mass in the left axilla. Histopathologic examination of an excisional specimen indicated an adenocarcinoma compatible with breast carcinoma. Immunohistochemical analysis demonstrated that the mass was estrogen receptor (ER) (−), progesterone receptor (PR)(−), and human epidermal growth factor receptor type 2 (HER2) (−). A diagnosis of breast cancer originating from the accessory mammary gland in the axilla was made. Two years following surgery, the patient presented with a pulmonary lesion. Core needle biopsy was performed, and the lesion was found to be ER (−), PR(−), and HER2 (3+). The patient was successfully treated with single-agent trastuzumab. Single-agent trastuzumab could be a reasonable regimen for metastatic accessory breast cancer patients with HER2 overexpression for whom chemotherapy and endocrine therapy are not suitable.