Clinical performance of Xpert MTB/RIF on contrast-enhanced ultrasound-guided core biopsy specimens for rapid diagnosis of superficial tuberculous lymphadenitis in high TB burden settings

The diagnosis of superficial tuberculous lymphadenitis (TBLN) remains difficult due to low detection rate of etiology. To increase the diagnostic value for TBLN, contrast-enhanced ultrasound (CEUS) guided core biopsy was introduced to obtain the specimen followed by Xpert MTB/RIF (Xpert) and other methods testing and to explore the optimum diagnostic pattern for TBLN in China. A prospective study was performed on patients with suspected superficial TBLN. All patients underwent CEUS-guided core biopsy from which specimens were tested by histopathology, Xpert, acid-fast bacilli (AFB), and MGIT960 culture (MGIT960), respectively. The diagnostic values were calculated and compared. A total of 328 patients were included the study, 272 were diagnosed as TBLN (254 definite TB, 18 probable TB) and 56 cases with Non-TBLN, and 100% (272/272) of TBLN patients obtained diagnosis sampled by CEUS-guided core biopsy. The overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of comprehensive diagnosis on the specimens by CEUS-guided core biopsy for TBLN were 100% ( 272/272, 95% CI 98.26–100.00), 94.64% (53/56, 95% CI 84.20–98.61), 98.91% (272/275, 95% CI 96.58–99.72), and 100% (53/53, 95% CI 91.58–100%), respectively. Xpert obtained 93.31% (237/254) of etiology detection rate on the specimens sampling by CEUS-guided biopsy. The etiology detection rate was associated with histopathological caseous necrosis. Current examinations on specimens by CEUS-guided core biopsy can achieve a high diagnostic efficacy for TBLN. Pathological differentiation of CEUS-guided biopsy tissue, then followed by Xpert, may be the best pattern for the diagnosis of TBLN in high TB burden areas.