Features predicting malignancy in mediastinal lymph nodes by endobronchial ultrasound in Indian setting: Is it different?

Introduction: Various studies have evaluated ultrasound (USG) morphological characteristics to predict malignancy in endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA), primarily in staging of lung malignancies mainly in western population. The purpose of our study was to assess the utility of EBUS morphology of lymph nodes in predicting malignant cytology of transbronchial needle aspirates in Indian population with tubercular endemicity. Methods: EBUS was performed for evaluation of mediastinal lymphadenopathy irrespective of the underlying disease. Seven USG morphological features including shape, size (both short axis and long axis), margins, echogenic appearance, presence or absence of central hilar structures, coagulation necrosis sign, and central intranodal vessel were recorded. These characteristics were later correlated with the final histopathological diagnosis. Results: A total of 115 consecutive patients undergoing EBUS were studied. Of the total 199 lymph nodes evaluated, malignant cells were identified in 46 (23%) nodes, granulomas were identified in 56 (28%) nodes and nonspecific features were identified in 97 (49%) nodes. On univariate analysis size >14mm on short axis and 19mm on the long axis, presence of coagulation necrosis sign and indistinct margins were predictive of a malignant etiology. In the final multivariate model, predictive probability of 0.611 (95% CI 0.539-0.679) for malignancy was found if size was > 19 mm in long axis with indistinct margins. Conclusion: USG appearance of lymph nodes on EBUS appears to be less helpful in predicting malignancy in an Indian setting where tuberculosis is endemic.