From January 2005 to December 2012 a total of 57 patients out of 185. 479 women (0.03%) from the Screening Program in Cantabria, Spain, were found to have suspicious axillary lymph nodes with an otherwise normal mammogram,that required an ultrasound evaluation and a fine needle aspiration (44 cases) and/or a core needle biopsy (20 cases).

All patients underwent ultrasound scanning of the axilla that was carried out with a lineal 7 -12 Mhz transducer (MyLab 70XV, Esaote, Biomedica, Genoa, Italy).

The normal axillary node appear on the mammogram as a round or oval well-defined mass, isodense or hypodense compared with breast parenchyma, and containing a central area of hilar fat.

Lymph node cortical thickness and uniformity were the most im­portant criteria for distinguishing between normal and abnormal nodes. Normal lymph nodes have a reniform shape, a uniformly hy­poechoic cortex with a maximal thickness of 3 mm, smooth margins, and a central fatty hilum. Findings of cortical thickness in excess of 3 mm, eccentric thickening, irregular margins, and encroachment on or displacement of the fatty hilum are suggestive of a pathologic process.

All biopsies and fine needle aspirations were ultrasound-guided with a free hand  approach.

Core needle biopsies were performed with an automated fourteen-gauge needle with a 22 mm throw (Acecut, TSK, Laboratory; Japan). A minimum of three biopsy samples were obtained with additional samples collected at the discretion of the radiologist.