Benign transport of breast epithelium into axillary lymph nodes after biopsy.

The most important prognostic indicator of distant metastasis in breast cancer is histologic documentation of axillary lymph node metastasis. Controversy exists about the importance of micrometastases (< 0.2 cm), and current pathology practice includes a careful search for their presence. We describe the histologic findings in a series of axillary lymph node dissections taken approximately 2 weeks after breast biopsy. Each case has limited presence of epithelial cells in the subcapsular sinus of a draining lymph node that we attribute to mechanical transport of tumor and/or normal breast epithelium secondary to the previous surgical or needle manipulation. These cells were accompanied by hemosiderin-laden macrophages and damaged RBCs. While the clinical implication of these findings is unknown, we believe that it will be of no clinical significance and have no untoward prognostic effect.