US-guided core needle biopsy of axillary lymph nodes in patients with breast cancer: why and how to do it.

Axillary lymph node status is an extremely important prognostic factor in the assessment of new breast cancer patients. Sentinel lymph node biopsy is now often performed instead of axillary dissection for lymph node staging but raises numerous issues of practicality. Sentinel lymph node biopsy can be avoided if lymph node metastasis is documented presurgically, making an alternative staging method desirable. Although not widely performed for axillary lymph node staging, ultrasonography (US)-guided core needle biopsy is a well-established procedure for the breast and other organs, with a higher success rate in terms of tissue diagnosis than fine-needle aspiration biopsy. Improvements in US have established it as a valuable method for evaluating lymph nodes. US findings in abnormal lymph nodes include cortical thickening and diminished or absent hilum. In addition, color Doppler US of abnormal axillary lymph nodes often shows hyperemic blood flow in the hilum and central cortex or abnormal (nonhilar cortical) blood flow. US-guided core needle biopsy of axillary lymph nodes in breast cancer patients can yield a high accuracy rate with no significant complications, given the use of a biopsy device with controllable needle action, a clear understanding of anatomy, and good skills for controlling the needle. Copyright RSNA, 2007.