Needle Based Confocal Laser Endomicroscopy (nCLE) for Diagnosing Malignant Pleural Mesothelioma

Background: Pleural biopsies in patients with malignant pleural mesothelioma (MPM) are frequently inconclusive and feature fibrosis. Needle based confocal laser endomicroscopy-(nCLE)- enables real-time imaging on a cellular level. It has potential as a guiding technique to increase the rate of representative biopsies by identification of areas with malignant cells (smart needle). Methods: Prospective study in patients with (suspected) MPM based on (PET)-CT imaging scheduled for pleural biopsies, received 2.5ml fluorescein intravenously immediately preceding the procedure. In-vivo nCLE imaging (AQ19-flex,Mauna Kea Technologies,Paris,France) of the pleura and ex-vivo imaging of the biopsies were performed and correlated with pathology. Results: 14 diagnostic biopsy procedures (surgery (n=2), thoracoscopy (n=2), CT- (n=3) , ultrasound-(n=6), EUS-guided (n=1)) including nCLE measurements were performed (pathology diagnosis: MPM n=6 (epithelial n=5, mesenchymal n=1), connective tissue/fibrosis n=5, NSCLC n=3. CLE imaging could clearly distinguish fibrotic pleural tissue (bright linear bands) from tumor-areas (dark enlarged pleomorphic cells/dark clumps) (Figure 1). No study related adverse events occurred. Conclusion: Needle-based pleural CLE distinguished groups of MPM cells from fibrotic pleural tissue. Therefore, nCLE has potential as a real-time guidance tool and might decrease the high current false negative biopsy rate.