Unusual Contralateral Axillary Lymph Node Metastasis in a Second Primary Breast Cancer Detected by FDG PET/CT and Lymphoscintigraphy.

Contralateral metastatic axillary lymph nodes in a patient with breast cancer is a rare condition. Here, we present a 55-year-old woman with a second primary breast cancer. The patient underwent 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for staging work-up. Additionally, preoperative lymphoscintigraphy was performed to detect sentinel lymph nodes. FDG PET/CT demonstrated increased FDG uptake in the left nipple and right axillary lymph nodes. Lymphoscintigraphy identified the right axillary lymph nodes which was consistent with the FDG PET/CT findings. This case emphasizes the usefulness of FDG PET/CT and lymphoscintigraphy for identifying unpredictable contralateral axillary lymph node metastasis from a second primary breast cancer.