Benign lymph nodes can often be differentiated from malignant nodes based on size, morphology, and vascularity, although there is a wide range of reported sensitivity and specificity for axillary US. The reported sensitivity can range from 26.4% to 94% and specificity from 53% to 98% [58,81,82]. Axillary US alone has a relatively low NPV and sensitivity to be useful as a 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]. US-guided core needle biopsy was superior to US- guided FNA in a meta-analysis of 1,353 patients with newly diagnosed invasive breast carcinoma, with a reported sensitivity of 88% for core biopsy and 74% for FNA [86]. US features associated with a higher likelihood of malignancy include short-axis lymph node size >1 cm, cortical thickness of >0.3cm, and absence of a fatty hilum [87-90]. However, these imaging features are not specific enough to avoid the need for histologic sampling. Since the Z0011 trial, there continues to be variability in incorporating axillary US into practice. Those in favor of performing axillary US routinely argue that >3 abnormal nodes or a positive axillary lymph node on needle biopsy warrant ALND rather than SLNB because these patients tend to have a high nodal tumor burden [58,91]. Those not in favor of performing axillary US recommend proceeding with SLNB, even if the preoperative US identify malignant-appearing lymph node(s) because the specificity of US is relatively low. Variant 5: Female. Newly diagnosed breast cancer, greater than 2 cm, with clinical node-negative. Initial imaging of the axilla following diagnostic mammography or DBT. Lymph node staging is crucial in the management of breast cancer, and several multicenter trials have impacted the approach to axillary lymph node treatment in breast cancer patients.
Imaging of the Axilla. Benign lymph nodes can often be differentiated from malignant nodes based on size, morphology, and vascularity, although there is a wide range of reported sensitivity and specificity for axillary US. The reported sensitivity can range from 26.4% to 94% and specificity from 53% to 98% [58,81,82]. Axillary US alone has a relatively low NPV and sensitivity to be useful as a 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]. US-guided core needle biopsy was superior to US- guided FNA in a meta-analysis of 1,353 patients with newly diagnosed invasive breast carcinoma, with a reported sensitivity of 88% for core biopsy and 74% for FNA [86]. US features associated with a higher likelihood of malignancy include short-axis lymph node size >1 cm, cortical thickness of >0.3cm, and absence of a fatty hilum [87-90]. However, these imaging features are not specific enough to avoid the need for histologic sampling. Since the Z0011 trial, there continues to be variability in incorporating axillary US into practice. Those in favor of performing axillary US routinely argue that >3 abnormal nodes or a positive axillary lymph node on needle biopsy warrant ALND rather than SLNB because these patients tend to have a high nodal tumor burden [58,91]. Those not in favor of performing axillary US recommend proceeding with SLNB, even if the preoperative US identify malignant-appearing lymph node(s) because the specificity of US is relatively low. Variant 5: Female. Newly diagnosed breast cancer, greater than 2 cm, with clinical node-negative. Initial imaging of the axilla following diagnostic mammography or DBT. Lymph node staging is crucial in the management of breast cancer, and several multicenter trials have impacted the approach to axillary lymph node treatment in breast cancer patients.