Sentinel Lymph Node Detection in Contralateral Axilla at Initial Presentation of a Breast Cancer Patient: Case Report.

The main basin for breast lymphatic drainage is ipsilateral axilla. However, extra-axillary drainage may be seen in some patients. The most common extra-axillary site is internal mammary chain, while contralateral axillary drainage is an extremely rare situation in previously untreated patients. We describe a case of untreated right breast retroareolar carcinoma with contralateral axillary drainage detected on preoperative lymphoscintigraphy. Contralateral axillary dissection was performed based on the result of frozen section examination of the sentinel lymph node (SLN) which turned out to burden micrometastasis. Postoperative histopathological examination revealed invasive ductal carcinoma metastasis in 17 out of 22 lymph nodes from the ipsilateral axillary dissection, whereas 14 lymph nodes from contralateral axillary dissection other than the SLN were nonmetastatic. In our opinion, determination of contralateral axillary metastasis in primary staging process had a major contribution to the management of the patient.