Inflammatory appearance of the parietal pleura at thoracoscopy - What does it hide?

Medical thoracoscopy (MT) is a well-established diagnostic procedure in cases of unexplained exudative pleural effusions. Despite the advantages of MT, challenges remain since occasionally malignancies mimic pleural inflammation.

To assess the relationship between the macroscopic appearance of the pleura at MT, the histology of the pleural biopsy and the final diagnosis after follow up.

Data was prospectively collected on patients undergoing MT over 8 years, using a standardised electronic thoracoscopy report. We report the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of the macroscopic changes, the sensitivity of computer tomographic (CT) appearances and final outcome.

A total of 228 thoracoscopies and biopsy were performed, 70 reports described benign macroscopic changes; of these 15.7% had malignant histology. When the final outcome was taken into account, the sensitivity of macroscopic appearance at MT was 91.5%, specificity 76.0%, PPV 88.6% and the NPV 81.4%. Nodular changes were more likely to be associated with malignancy (Chi² 75.5, p < 0.05). The CT scans performed prior to thoracoscopy had a poor sensitivity for the diagnosis of malignant pleural effusion (50%) and a good specificity in the diagnosis of benign disease (90.5%).

A standardised structured report allows reliable evaluation of the macroscopic findings at MT. The PPV of the macroscopic findings for malignancy is relatively high; however, in a significant minority of cases despite benign-looking macroscopic changes the final diagnosis was malignancy. Careful consideration must be given in cases with benign histology to either monitoring or further diagnostic tests based on clinical suspicion.