Diagnostic utility of endobronchial ultrasound features in differentiating malignant and benign lymph nodes

Endobronchial ultrasound (EBUS) features have been shown to be useful in predicting etiology of enlarged malignant lymph nodes. However, there is dearth of evidence especially from developing countries. We assessed the EBUS characteristics across various mediastinal and hilar lymphadenopathies. In this prospective study, all patients with mediastinal and hilar lymphadenopathy on CT Chest and who were planned for EBUS-FNA (Fine Needle Aspiration) were included. EBUS features of lymph nodes studied were shape, size, margins, echogenicity, central hilar structure (CHS), coagulation necrosis sign and colour power doppler index (CPDI). These were scored and compared between benign and malignant lymphadenopathies. A total of 86 lymph nodes in 46 patients were prospectively studied of which 23 (26.7%) were malignant, 27 (31.3%) tuberculosis and 36 (41.8%) sarcoidosis. There was significant difference between malignant and benign lymph nodes in terms of CHS [central hilar structutre] (p=0.011), margins (p=0.036) and coagulation necrosis sign (p<0.001). On comparison of features of malignancy and tuberculosis, there were significant differences in margins (p=0.016) and coagulation necrosis sign (p 0.001). However, when malignancy and sarcoidosis was compared, there were differences in echogenicity (p=0.002), CHS (p=0.009) and coagulation necrosis sign (p<0.001). Only coagulation necrosis sign was found to be highly consistent with malignant lymph nodes. The other features cannot be used to distinguish malignant from benign lymph nodes, especially in a developing country like India where tuberculosis is a common cause of mediastinal lymphadenopathy.