Abstract:

Objective To explore the clinical value of polymerase chain reaction (PCR) test in diagnosis of pulmonary tuberculosis (PTB) by using CT-guided lung biopsy specimens.Methods A retrospective study was conducted by collecting information and data from a total of 111 patients, who visited Shanghai Pulmonary Hospital from January 2017 to March 2018 and were suspected to have PTB at beginning, finally, by pathological test or experimental therapy with anti-TB drugs, 73 (65.8%) cases were confirmed to be PTB patients and 38 (34.2%) cases were non-TB patients (3 patients had sarcoidosis, 17 patients had lung cancer, 3 patients were infected by cryptococcus, 4 patients were infected by aspergillus, 3 patients had lung abscess, 2 patients had foreign body granuloma and 6 patients had bronchiectasis). The biopsy specimens were obtained from all enrolled 111 patients by using CT-guided lung puncture and smear cytopathology examination was performed; among them, the biopsy specimens were obtained from 13 cases by using CT-guided coarse needle lung puncture and histopathological examination was performed because the diagnosis of those patients couldn’t be confirmed after cytopathology examination had been conducted for 2 times. At the same time, PCR test was also performed to those biopsy specimens to detect Mycobacterium tuberculosis (MTB) DNA. The final clinical diagnosis was regarded as a standard. Based on the clinical diagnosis results, the sensitivity, specificity, positive and negative predictive values, correct indices (consistency) of TB-PCR test in diagnosis of PTB by using cytopathological specimens, as well as the effects of TB-PCR test by using histopathological specimens were explored. SPSS 21.0 software was used for statistical analysis of the data. Count variables were analyzed by χ² test and P<0.05 was regarded as statistically significant difference. Results Regarding the final clinical diagnosis as a standard, the sensitivity, specificity, positive predictive value, negative predictive value and correct indices of TB-PCR test in PTB diagnosis by using cytopathological specimens were 83.6% (61/73), 89.5% (34/38), 93.8% (61/65), 73.9% (34/46) and 0.73 respectively. The positive rate of TB-PCR for PTB was 83.6% (61/73), which was significantly higher than that of single cytopathological examination (39.7% (29/73) (χ²=29.663, P=0.000). Among 73 cases with PTB, TB-PCR test by using histopathological specimens were performed in 13 cases and the results were positive in 8 cases; the results of TB-PCR test by using cytopathological specimens were positive in 12 cases. Among the PTB patients, 9 patients (12.3%, 9/73) were not diagnosed as TB by cytopathological and histopathological examinations, as well as the traditional tests (such as sputum smear microscopy and sputum culture); however, 4 patients were positive through TB-PCR test by using cytopathological specimens. Conclusion The diagnosis rate of PTB can be improved by using TB-PCR test with CT-guided lung biopsy specimens and this method has valuable of clinical application.

Key words: Tuberculosis, pulmonary, Biopsy, fine-needle, Polymerase chain reaction, Sensitivity and specificity, Evaluation study