Diagnostic yield of endoscopic ultrasound-guided fine-needle aspiration of tubercular lymphadenitis using combination of cytology and Gene Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) genes

Abstract

Diagnostic yield of an automated molecular test, Gene Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF), was evaluated in this study to simultaneously detect the MTB gene and resistance to rifampicin (RIF) on cytology samples acquired via endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNAC) in suspected tubercular lymphadenitis. Microscopy, cytology, Gene Xpert MTB/RIF assay data on Acid-fast bacillus (AFB), and traditional culture of lymph nodes were retrospectively analyzed. Thirty-one patients (median age 33.5 years, inter-quartile range [IQR] 21-66, 18, 58% female) presented with fever (28, 90%), dysphagia (2, 7%), and recurrent subacute intestinal obstruction (1, 3%). Gene Xpert showed higher sensitivity (30, 97%) compared to the other tests: cytology (23, 77%; odds ratio [OR] 8.8, 95% confidence interval [CI] 1.0-76.9; p = 0.05), AFB smears (12, 39%; OR 50, 95% CI 5.9-420.4; p = 0.00001), and conventional culture (4, 13%; OR 188.5, 95% CI 19.7-1796.3; p = 0.0000). We conclude that Gene Xpert MTB/RIF test on EUS-guided FNAC samples is very useful to diagnose tubercular lymphadenitis.

Keywords: Acid-fast bacillus; Acquired immunodeficiency syndrome; Anti-tubercular treatment; Drug-resistant tuberculosis; Mediastinum; Pyrexia; Tuberculosis; Ziehl-Neelsen (ZN) stain.