Sentinel lymph nodes in breast cancer can be falsely positive

The presence of epithelial cells in axillary sentinel lymph nodes does not necessarily mean the patient has metastatic breast carcinoma.  Cells (and other material) can be transported to the sentinel lymph nodes by physiologic drainage of a biopsy site after iatrogenic displacement.  We reported 25 cases in which the cytologic and immunohistochemical features of epithelial cells in sentinel lymph nodes were completely different from those of their respective patient’s carcinomas.  Most of the patients had intraductal carcinoma without evident invasion.  In the majority of cases the cells appeared to originate from intraductal papillomas which had been core biopsied causing their cells to be displaced into stroma and subsequently transported to the nodes.  Without careful pathologic analysis, this phenomenon can lead to a false positive diagnosis of metastasis; however, the process may not be limited to benign cells, and, in theory, it could account for some of the discrepant literature regarding the clinical relevance of micrometastases.  The development of a metastasis-specific marker would be crucial in this regard.   

Bibliographical reference:

Bleiweiss IJ et al.: "Axillary sentinel lymph nodes can be falsely positive due to iatrogenic displacement and transport of benign epithelial cells in patients with breast carcinoma", J Clin Oncol. 2006 May 1;24(13):2013-8

Ira J Bleiweiss

Lillian and Henry Stratton/Hans Popper Department of Pathology, Mount Sinai School of Medicine, New York, NY, USA