Ultrasound imaging of the normal axilla: Anatomical characteristics of lymph nodes and age-related variations

To describe the ultrasound characteristics of axillary lymph nodes in healthy individuals and analyse how these characteristics vary with age.

Between February and April 2021, we enrolled a total of 91 healthcare professionals from our centre with no relevant medical history. All participants underwent an axillary ultrasound before participating in the COVID-19 vaccination campaign. The following parameters were recorded: total number of visible lymph nodes, maximum longitudinal diameter and cortical thickness, Bedi classification, and signal intensity on colour Doppler evaluation. We compared the data collected between two age groups [young (<45 years) vs middle-aged (≥45 years)] using the Student's t-test for continuous quantitative variables and the Mann-Whitney U test for ordinal variables. Variables with a p-value < 0.05 were considered statistically significant.

An average of 2.96 lymph nodes was observed, with mean maximum longitudinal diameter and cortical thickness of 15.8 mm and 1.6 mm, respectively. Regarding the Bedi classification and colour Doppler scale, types 2 and 1 were the most common. A comparative analysis between the two age groups showed significantly higher values for cortical thickness, Bedi classification, and colour Doppler classification in the younger volunteers (p < 0.05).

Our study highlights the radiological differences between lymph nodes in young and middle-aged volunteers under baseline conditions, emphasizing the importance of careful assessments of borderline-appearing nodes in older patients, especially in oncological contexts.