Differentiating tuberculosis from sarcoidosis by sonographic characteristics of lymph nodes on endobronchial ultrasonography: A study of 165 patients

Abstract

The differential diagnosis of sarcoidosis and tuberculosis is difficult, especially in countries with a high tuberculosis burden. We hypothesized that sonographic features on endobronchial ultrasonography (EBUS) would help in differentiating tuberculosis from sarcoidosis. In this study, the endosonographic features of tuberculosis and sarcoidosis are compared. This was a retrospective analysis of prospectively collected data of patients with intrathoracic lymphadenopathy who underwent EBUS-guided transbronchial needle aspiration (TBNA), and were finally diagnosed with sarcoidosis or tuberculosis. Sonographic features such as size, shape (round or oval), margin (distinct or indistinct), echogenicity (heterogeneous or homogeneous), presence or absence of a central hilar structure, and coagulation necrosis sign were recorded and compared in the 2 groups. During the study period, 249 EBUS-guided TBNA procedures were performed and a diagnosis of sarcoidosis (n=118) or tuberculosis (n=47) was made in 165 patients. A total of 358 lymph node stations were examined. Heterogeneous echotexture (53.4% vs 12.6%, P<.001) and coagulation necrosis (26.1% vs 3.3%; P<.001) were significantly higher in tuberculous lymph nodes. A combination of a positive tuberculin skin test (TST) and either heterogeneous echotexture or coagulation necrosis sign had specificity of 98% and positive predictive value of 91% for a diagnosis of tuberculosis. Sonographic features of heterogeneous echotexture or coagulation necrosis in the lymph nodes on EBUS are fairly specific for tuberculosis. Along with a positive TST, these features strongly favor a diagnosis of tuberculosis over sarcoidosis.