The diagnostic utility of ultrasound elastography to differentiate tuberculosis and sarcoidosis during endobronchial ultrasound-guided transbronchial needle aspiration (ebus-tbna)  

K. Madan*^a (Dr), M. Madan^a (Dr), S. Mittal^a (Dr), V. Hadda^a (Dr), A. Mohan^a (Dr), R. Guleria^a (Dr)

^a All India Institute of Medical Sciences (AIIMS), New Delhi, India, New Delhi, INDIA

* drkaranmadan@gmail.com

Introduction: Elastography is a noninvasive tool that may allow differentiation between benign and malignant lymph nodes during Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). In TB endemic areas, clinico-radiological features of mediastinal tuberculosis (TB) and Sarcoidosis often overlap, rendering an accurate diagnosis challenging. There is interest in the identification of modalities to aid in this differentiation. There are currently no published data on the utility of EBUS-elastography in differentiating between TB and Sarcoidosis.

Methods: Subjects undergoing EBUS-TBNA were prospectively enrolled, and elastography features were observed. Subjects with definitive diagnosis of TB or Sarcoidosis were enrolled. The elastography features recorded included the three-color classification patterns and strain ratio.

Results: We enrolled 96 subjects with a definitive diagnosis (53: TB and 43: Sarcoidosis). Of the 27 patients in whom the lymph nodes were classified as Type 1 on endobronchial ultrasound elastography color pattern, 17 had a diagnosis of tuberculosis (TB) (62.9%), while 10 (37%) were Sarcoidosis. For Type 2 lymph nodes, 20/45 (44.4%) were TB, and 25/45 (55.6%) were sarcoidosis. Type 3 lymph nodes were TB in 16/24 (66.7%) and sarcoidosis in 8/24 (33.3%). In classifying Type 1 as 'sarcoidosis' and Type 3 as 'tubercular,' the sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were 48.5 %, 55.6 %, 66.7%, 37 %, and 0.51, respectively. The strain ratio [Median (IQR)] was 1.29 (0.37-5.98) in TB, and 2.10 (0.83-4.52) in sarcoidosis group (p=0.48).

Conclusion: Ultrasound Elastographic lymph node characteristics have a limited diagnostic utility to differentiate between TB and Sarcoidosis during EBUS-TBNA.

Disclosure of funding source(s): none