Introduction: Minimally invasive diagnosis of chest wall tuberculosis remains a challenge. Fine needle aspiration (FNA) is a simple and safe method of sampling. However, previous studies have shown that conventional tuberculosis tests had poor diagnostic performance in the needle aspirates. With the popularization of molecular detection application, the value of FNA in the diagnosis of chest wall tuberculosis needs to be reevaluated.
Methods: We retrospectively studied patients with suspected chest wall tuberculosis at admission who underwent FNA for diagnosis and reported the diagnostic efficacy of acid-fast bacilli smear, mycobacterial culture, cytology and Xpert MTB/RIF (GeneXpert) when testing FNA specimens. A composite reference standard (CRS) was used as the diagnostic gold standard for this study.
Results: Among 89 included FNA specimens, acid-fast bacilli smear, mycobacterial culture, and GeneXpert were positive in 15 (16.85%), 23 (25.8%), and 61 (68.5%), respectively. Thirty-nine (43.8%) had cytologic features suggestive of tuberculosis. According to CRS, 75 (84.3%) cases were categorized as chest wall tuberculosis, 14 (15.7%) were not diagnosed with tuberculosis. Using CRS as the gold standard, acid-fast bacilli smear, mycobacterial culture, cytology and GeneXpert exhibited sensitivity of 20%, 30.7%, 52% and 81.3%, respectively. Specificity in these four tests was found to be 100%. Sensitivity of GeneXpert was significantly higher than that of smear, culture and cytology, X₂=66.3, p < 0.001.
Conclusion: GeneXpert achieved higher sensitivity as compared to cytology and conventional TB tests in the chest wall FNA specimens. The implementation of GeneXpert may increase the diagnostic efficacy of FNA in the diagnosis of chest wall TB.
Keywords: chest wall tuberculosis, fine needle aspiration, Xpert MTB/RIF, cytology, culture