Preoperative Sonographic Assessment of Axillary Lymph Nodes in Newly Diagnosed Invasive Breast Cancer

Objective: To assess the sonographic features and fine needle aspiration of ipsilateral metastatic axillary lymph nodes of newly diagnosed invasive breast cancer. Methods: This was a retrospective review of the sonographic features of ipsilateral axillary lymph nodes of patients with newly diagnosed invasive breast cancers, attending a single radiology centre from January 2014 to December 2016. Among 449 axillae review, 362 axillae of 355 breast cancer patients with available sonographic images and surgical histopathology or positive fine needle aspiration cytology were analysed. Qualitative morphological assessments and quantitative measurements of the axillary lymph nodes were performed. Results: Various dimensions, areas, and ratios of the entire lymph node and its cortex were associated with nodal metastasis (p < 0.001), with the maximal cortical thickness showed superior performance. Using a 4-point grading system, the sonographic morphological features including focal cortical thickening, hilar displacement or replacement, and perinodal infiltration were associated with nodal metastasis (p < 0.001) with sensitivity 65.2% (95% confidence interval [CI] = 58.2%-71.8%) and specificity 96.9% (95% CI = 92.9%-99.0%). With the surgical histopathological result as the reference standard, the ultrasound-guided fine needle aspiration cytology showed moderate sensitivity 74.7% (95% CI = 63.3%-84.0%) and high specificity 100% (95% CI = 92.3%-100%). Conclusion: Axillary ultrasound helps in preoperative axillary nodal staging of patients with invasive breast cancer. Ultrasound-guided fine needle aspiration cytology offers additional information to the metastatic nodal status with high specificity.