Male Accessory Breast Cancer Successfully Treated With Single-Agent Trastuzumab: A Case Report
Wencai Ji1,2, Wenbin Guo1
1Department of Surgery, The Breast Center, Dalian Central Hospital, Dalian Medical University, Dalian, China.
Abstract:
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.
Insights
This study reports a rare case of male accessory breast cancer. Single-agent trastuzumab effectively treated metastatic disease in a patient with HER2-overexpressing cancer.
Area of Science:
- Oncology
- Endocrinology
Background:
- Male accessory breast cancer is exceptionally rare, with limited data on monotherapy outcomes before 2022.
- This case involves a 76-year-old male diagnosed with adenocarcinoma of the axillary accessory mammary gland.
Observation:
- Initial tumor was estrogen receptor (ER) negative, progesterone receptor (PR) negative, and human epidermal growth factor receptor type 2 (HER2) negative.
- Two years post-surgery, the patient developed a pulmonary metastasis.
Findings:
- The metastatic lesion was identified as ER negative, PR negative, and HER2 positive (3+).
- The patient achieved successful treatment outcomes with single-agent trastuzumab therapy.
Implications:
- Single-agent trastuzumab presents a viable therapeutic option for metastatic accessory breast cancer with HER2 overexpression.
- This approach is suitable for patients ineligible for chemotherapy or endocrine therapy.
