Contralateral axillary lymph node metastasis in primary breast cancer: A case report.

INTRODUCTION: Contralateral axillary lymph node metastasis (CAM) is rare, especially in primary breast cancer. PRESENTATION OF CASE: A 71-year-old woman visited our hospital after noticing a mass in her right breast. A mass of 5 cm in diameter with skin infiltration was palpable on the medial side of the right breast. She underwent a needle biopsy and was diagnosed with invasive ductal carcinoma. On various imaging modalities, there were no distant metastases but bilateral axillary lymph node metastases were found. She underwent preoperative chemotherapy and showed a clinical partial response. After thorough discussion, she opted for surgery and underwent partial mastectomy of the right breast and bilateral axillary lymph node dissection. Histopathological examination revealed residual breast tumor and one metastatic axillary lymph node on each side. Postoperative radiotherapy and hormone therapy were performed. The patient is alive and recurrence-free as of 1 year after the start of treatment. CONCLUSION: CAM is often regarded as distant metastasis, but can be considered curable if there is no distant metastasis to other organs. CAM without distant metastasis to other organs should be treated with curative intent in order to avoid a disadvantage to the patient.