Role of Flexi-Rigid Thoracoscopy in Undiagnosed Pleural Effusions and Correlation of Visual Appearance of Pleura on Thoracoscopy with the Final Diagnosis
Authors: Periwal Pallavi , Khanna Arjun , Talwar Deepak 
Published: November 2023

Background:
Undiagnosed pleural effusions (UPE) account for roughly 25% of cases of all pleural effusions. Minimally invasive flexi-rigid thoracoscopy has high diagnostic yield. Some previous studies have looked into the correlation of the thoracoscopic findings and the final etiological diagnosis, however, data are scarce. This study is aimed to know the role of flexi-rigid thoracoscopy in establishing etiological diagnosis in undiagnosed, treatment naïve pleural effusion patients and the correlation of thoracoscopic findings with the final diagnosis.

Materials and Methods:
A retrospective descriptive observational study was conducted on 84 newly diagnosed patients in whom pleural effusion remained undiagnosed at the Department of Respiratory, Sleep, Allergy and Critical Care Medicine at the Metro Centre for Respiratory Diseases, Metro Hospital, Noida. Data from hospital records of patients, who were subjected to flexi-rigid thoracoscopy, was collected between January 2010 and December 2013 and analyzed. The diagnostic yield of pleural biopsy using flexi-rigid thoracoscope in UPEs was assessed and the visual appearance of pleura on thoracoscopy was correlated with the final diagnosis.

Results:
The diagnostic yield of flexi-rigid thoracoscopy in UPEs is 89.28%. When nonspecific pleuritis is considered as a diagnosis, the diagnostic yield increases to 97.6%. The pleural biopsy histopathological examination revealed Nonspecific pleuritis in 14.2% of patients, granuloma consistent with tuberculosis (TB) in54.8%, malignancy in 28.6% of patients confirmed on immunohistochemistry and in 2.3% the diagnosis remained inconclusive. Out of the 12 patients, two were diagnosed to have TB on the basis of pleural biopsy acid-fast bacilli culture showing mycobacterium TB. Post coronary artery bypass graft pleuropericardial effusion, chylothorax, and congestive heart failure were diagnosed in 1 case each, while the diagnosis remained uncertain in 7. The thoracoscopic finding of adhesions had negligible and no statistically significant correlation to the final diagnosis. The presence of pleural nodularity had a negative correlation with nonspecific pleuritis and a positive correlation with malignancy although statistically insignificant. It was seen that small and uniform nodules had a positive correlation with TB. The presence of large and variable-sized nodules had a strong positive correlation with malignancy. The presence of diaphragmatic nodules has a positive correlation with malignancy. Pleural infiltration has a strong positive correlation with malignancy and negative correlation with TB.

Conclusion:
Flexi-rigid pleuroscopy is an excellent modality to investigate UPE since it has a high diagnostic yield, is minimally invasive and safe procedure. The presence of a variable distribution of nodules, large nodules, diaphragmatic nodules, visceral pleural infiltration has a strong positive correlation with malignancy and increases the likelihood of malignancy as the final diagnosis. However, the visual appearance of the pleura is a subjective finding and possibly more informative when used by an experienced pulmonologists in combination with the pleural biopsy for the final diagnosis.