Correlation between sonographic features of mediastinal lymph nodes and presence of malignancy when performing EBUS-TBNA

Introduction: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has been replacing the surgical method in the study of mediastinal lymph nodes. Many studies have tried to define typical ultrasound criteria for malignant mediastinal lymph nodes. These features include size >10mm, absence of echogenic hilar structure and nodal vessel, heterogeneous echo pattern and distinct margins. Objective: To study the correlation between endosonographic features of lymph nodes and malignancy. Methods: Retrospective study carried out on patients with mediastinal adenopathies under investigation, admitted for EBUS-TBNA, between January 2020 and December 2021. Lymph node features, number of punctures and histology were analysed. Results: A total of 561 lymph nodes from 343 patients were analysed. 257(74,9%) were male patients. The most frequently punctured lymph node station was 7 (n=217; 38.7%), followed by 4R (n=143; 25.5%) and 4L (n=52; 9,3%). The mean size of the short axis was 13.2mm (min:3.5, max:54.8, median 14.4). Among the characteristics studied (shape, size, presence of hilar structure, presence of vessels, margins, echogenicity, lymph node station), the following were statistically associated with malignancy: short axis size >10mm (p=0.0001), heterogeneous echo pattern (p=0.003) and lymph node stations 2R, 2L, 4R and 11R (p=0.001). Conclusion: The size of lymph nodes, its echogenicity and lymph node’s location have shown correlation with malignancy. Better defined sonographic criteria are needed to help select the lymph nodes to be punctured.