Unexpected contralateral axillary lymph node metastasis without ipsilateral involvement in triple-negative breast cancer: A case report and review of literature.

Background: Breast cancer is a leading cause of cancer-related mortality among women worldwide, with invasive ductal carcinoma (IDC) being the most prevalent subtype. Lymph node metastasis is the primary prognostic indicator, typically evaluated via biopsy of the ipsilateral sentinel or axillary lymph nodes. Contralateral axillary metastasis (CAM) without ipsilateral involvement is exceedingly rare, particularly in early-stage breast cancer. This report presents a case of CAM in a patient with triple-negative breast cancer (TNBC), underscoring diagnostic and therapeutic complexities.

Case summary: A 73-year-old female presented with left-sided early-stage IDC in February 2023. Despite a modified radical mastectomy and pathologically negative ipsilateral lymph nodes, a postoperative positron emission tomography (PET) scan detected fluorodeoxyglucose-avid nodes in the contralateral axilla. Biopsy confirmed metastatic ductal carcinoma with triple-negative status, resulting in an upstaged diagnosis of metastatic breast cancer, stage IV, M1. The patient underwent six cycles of adjuvant chemotherapy, with follow-up PET imaging showing regression of the contralateral lesion. This case highlights the importance of advanced imaging in TNBC for precise staging and treatment optimization.

Conclusion: This case highlights the aggressive nature of TNBC and the need for advanced imaging to ensure accurate staging and effective management.