A case of lymph node dissection for contralateral axillary lymph node metastasis of ipsilateral breast tumor recurrence after identifying the primary lymphatic drainage by lymphoscintigraphy.

We report a case of total mastectomy and contralateral axillary lymph node dissection (ALND) in a patient with ipsilateral breast tumor recurrence (IBTR) and contralateral axillary lymph node metastasis (ALNM), with lymphoscintigraphy, confirming that the primary lymphatic flow was directed to the contralateral ALNM. The patient in the present case study is a 63-year-old woman. At the age of 46 years, the patient underwent lumpectomy and sentinel lymph node biopsy (SLNB) for left breast cancer. After surgery, she underwent whole-breast irradiation and hormone therapy (tamoxifen) for 5 years. On follow-up, she did not have recurrence. When she underwent breast ultrasound examination at the 17-year checkup after the initial surgery, she was diagnosed with tumor recurrence in the left conserved breast and with contralateral ALNM, without distant metastasis to any other organ. When re-SLNB is performed in patients with IBTR, the primary lymphatic flow is directed toward a lymph node other than the ipsilateral axillary lymph node (ALN). Therefore, it is necessary to discuss whether or not the contralateral ALNM in our case should be treated as stage IV. Therefore, we performed ALND after confirming that the primary lymphatic flow was directed toward the contralateral ALN as observed on lymphoscintigraphy and considering the contralateral ALNM as a localized lesion. Lymphoscintigraphy and intraoperative fluorescence imaging aid in the identification of the primary lymphatic flow. Lymph node metastases beyond the altered primary lymphatic flow are treated as localized lesions, and aggressive surgery is expected to be effective. There is a need to formulate guidelines on the treatment of IBTR considering changes in primary lymphatic flow. © The Japan Society of Clinical Oncology 2021.