If a breast primary is of concern, mammography and/or DBT may assist in identifying a primary breast malignancy. Mammography is not optimal for evaluating the axilla. Valente et al [162] found that mammography has a high FNR in the detection of axillary metastatic lymphadenopathy. US Axilla If mammogram or DBT identifies a primary breast malignancy, then axillary US after mammogram and/or DBT may evaluate the nodal size, nodal cortical, and hilar morphology. The sensitivity and specificity for axillary US for differentiating benign from malignant nodes is variable, with reported sensitivity ranging from 26% to 94% and specificity from 53% to 98% [58]. Axillary US alone has relatively low NPV and sensitivity and therefore is not a reliable predictor of axillary nodal burden [83,84]. When combined with needle biopsy, however, the sensitivity improves from 61% to 79% in a meta-analysis of 21 studies [54,62,85]. Some US features that are more likely to be associated with malignancy include short-axis diameter >1 cm, cortical thickness >0.3 cm, and absence of a fatty hilum [87-90]. The absence of a fatty hilum has the highest PPV (90% to 93%) for malignancy [103,104]. A suspicious node on US warrants percutaneous biopsy because a positive axillary US helps to identify those patients at risk for higher tumor burden [54,55]. However, a negative axillary US with or without biopsy does not rule out nodal disease [58]. US-Guided Core Biopsy Axillary Node Based on a meta-analysis of 1,353 patients with newly diagnosed breast cancer, US-guided core needle biopsy is superior to US-guided FNA with a reported sensitivity of 88% for core biopsy and 74% for FNA [86]. The overall sensitivity of US-guided biopsy ranges from 52% to 90%, whereas the specificity ranges from 98% to 100% [59- 63]. Imaging of the Axilla
Imaging of the Axilla. If a breast primary is of concern, mammography and/or DBT may assist in identifying a primary breast malignancy. Mammography is not optimal for evaluating the axilla. Valente et al [162] found that mammography has a high FNR in the detection of axillary metastatic lymphadenopathy. US Axilla If mammogram or DBT identifies a primary breast malignancy, then axillary US after mammogram and/or DBT may evaluate the nodal size, nodal cortical, and hilar morphology. The sensitivity and specificity for axillary US for differentiating benign from malignant nodes is variable, with reported sensitivity ranging from 26% to 94% and specificity from 53% to 98% [58]. Axillary US alone has relatively low NPV and sensitivity and therefore is not a reliable predictor of axillary nodal burden [83,84]. When combined with needle biopsy, however, the sensitivity improves from 61% to 79% in a meta-analysis of 21 studies [54,62,85]. Some US features that are more likely to be associated with malignancy include short-axis diameter >1 cm, cortical thickness >0.3 cm, and absence of a fatty hilum [87-90]. The absence of a fatty hilum has the highest PPV (90% to 93%) for malignancy [103,104]. A suspicious node on US warrants percutaneous biopsy because a positive axillary US helps to identify those patients at risk for higher tumor burden [54,55]. However, a negative axillary US with or without biopsy does not rule out nodal disease [58]. US-Guided Core Biopsy Axillary Node Based on a meta-analysis of 1,353 patients with newly diagnosed breast cancer, US-guided core needle biopsy is superior to US-guided FNA with a reported sensitivity of 88% for core biopsy and 74% for FNA [86]. The overall sensitivity of US-guided biopsy ranges from 52% to 90%, whereas the specificity ranges from 98% to 100% [59- 63]. Imaging of the Axilla