The present study was approved by the Institutional Review Board of Chang Gung Memorial Foundation (IRB No.: 201902075B0). We retrospectively recruited 117 patients from April 2016 to August 2018 at Linkou Chang Gung Memorial Hospital, Taiwan, which is a tertiary referral medical center. Consecutive patients who underwent semi-rigid pleuroscopy within the study period were identified from the database and their demographic characteristics were recorded.
Diagnostic criteria of TB pleurisy
Patients with TB pleurisy were defined according to a previous study. They included patients with confirmed as well as probable TB pleurisy . A patient with confirmed TB pleurisy was defined as a patient with pleural fluid sample that was culture-positive for M. tuberculosis and/or a histopathological finding consistent with TB on pleural biopsy. A patient with probable TB pleurisy was defined as a patient with at least one of the following characteristics: 1) sputum specimen that was culture-positive for M. tuberculosis, 2) other biologic specimens that were culture-positive for M. tuberculosis, 3) raised pleural lymphocytes and protein levels, and 4) a positive response to anti-tuberculosis medication with absence of other possible causes of pleural effusion. According to previous studies [8, 9], patients with positive M. tuberculosis culture results represent a relatively small portion of all cases of TB pleurisy. The present study employed a combination of pleural M. tuberculosis culture, pleural pathologic analysis, and clinical diagnosis as the reference method for diagnosing TB pleurisy. To confirm the diagnosis of TB pleurisy, two senior physicians independently reviewed each patient’s clinical and laboratory records.
Procedure and Equipment
All patients underwent pleuroscopy performed by an experienced operator and two trained assistants. All patients received moderate sedation with fentanyl and midazolam with or without propofol during the procedure. Before starting the examination, chest ultrasound was performed to identify the optimal entry site with the patients in the decubitus position. After local administration of 2% lidocaine for anesthesia, a 1.0-cm skin incision was made followed by thoracotomy with an 8-mm flexible trocar (MAJ-1058, Olympus Medical Systems Corp., Japan). A semi-rigid thoracoscope (LTF-240; Olympus, Tokyo, Japan) was initially used for draining the effusion and for exploring the pleural cavity. Cryoprobe or a pair of forceps (FB-15C-1; Olympus, Tokyo, Japan) were used for biopsy through the working channel of the semi-rigid thoracoscope. A 1.9 or 2.4-mm flexible cryoprobe (Erbokryo CA, Erbe, Germany) was used to perform cryobiopsy with carbon dioxide as the cryogen. The cooling time of each cryobiopsy was approximately 3 seconds and the temperature of the probe tip reached approximately −70°C. At least three biopsies were considered the standard procedure in each patient. The biopsy area was restricted in parietal pleura. For histopathological analyses, all biopsy samples were transported in separate formalin containers. The biopsy samples were processed according to standard protocols for histopathological and immunohistochemical staining. After completing the biopsies, a drainage tube with a 16 Fr pigtail catheter (BT-PDS-1630-W-NK1; Bioteq, Taipei, Taiwan) was placed to monitor and drain the pleural effusion. The timing of catheter removal was decided by clinicians’ judgment based on the amount of pleural effusion (less than 50 ml) and the clinical condition.
The pleural and sputum specimens were processed according to the procedure described in a previous report . Briefly, pleural fluid and sputum specimens were stained with Ziehl-Neelsen stain for microscopic examination. Decontamination was performed using N-acetyl-L-cysteine-sodium hydroxide (BBL MycoPrep; Becton Dickinson, Cockeysville, MD, USA). The samples were cultured in BACTEC 12B vials (radiometric BACTEC 460TB system; Becton Dickinson, Franklin Lakes, NJ) and Lowenstein-Jensen medium (Bio-Rad, Marnesla-Coquette, France).
Each pleuroscopy image was evaluated for three features, namely the character of nodules, adhesion, and the distribution of the lesions. Three characteristic features were adopted for differentiating TB pleurisy from non-TB pleurisy: (1) lesions with sago-like nodules (Fig. 1A) or micronodules (Fig. 1B), (2) presence or absence of adhesion (Fig. 2), and (3) the distribution of the lesions (discrete or fused together) (Fig. 3). To define the absence or the presence of these three features among subjects, two senior pulmonologists evaluated and discussed each pleuroscopy image to arrive at a consensus.
Data were expressed as mean ± standard error of the mean. Student’s t-test was used for the comparison of continuous variables between patients with TB pleurisy and those with non-TB pleurisy, while Mann-Whitney U test was used for non-normal distributions. Categorical variables were compared with chi-squared test or Fisher’s exact test. Univariate logistic regression analysis with odds ratios and 95% confidence interval (CI) were used to assess the difference in diagnostic yields between the groups. The sensitivity, specificity, positive predictive value, and negative predictive value were expressed as 95% CI. Statistical significance was set at p < 0.05. Statistical Analyses were performed using SPSS version 13.0 (SPSS Inc.; Chicago, IL, USA).