Is Pre-Operative Axillary Staging with Ultrasound and Ultrasound-Guided Fine-Needle Aspiration Reliable in Invasive Lobular Carcinoma of the Breast?

Axillary ultrasound (US) with US-guided fine-needle aspiration (US-FNA) for suspicious lymph nodes is important for pre-operative staging and planning of surgical management. Invasive lobular carcinoma (ILC) metastases were previously thought to be difficult to detect, but with a limited amount of evidence. This study investigated the ability of US and US-FNA to detect ILC metastases by assessing 142 patients with ILC. The sensitivity of US in detection of metastasis was 52.3%, and US was able to exclude 96% of N2 and N3 axillary metastases. The false-negative rate of US-FNA in detection of metastasis for suspicious lymph nodes on US was 34.8%, and lymph nodes with longer maximal dimensions were associated with false-negative US-FNA results. Multiplicity of breast lesions and maximal cortical thickness ≥3.1 mm of lymph nodes were independently associated with metastasis. Although pre-operative US in ILC can reliably exclude advanced axillary nodal disease, US-FNA results should be carefully interpreted.