Probe-based confocal laser endomicroscopy for pleural malignancies diagnosis

Probe based confocal laser endomicroscopy (pCLE) is an optical imaging technique allowing live tissue imaging at a cellular level. Currently, this tool remains experimental. Two studies regarding pleural disease have been published and suggest that pCLE could be valuable for pleural disease investigations. However, normal and malignant pleural pCLE features remain unknown. Therefore, we conducted a prospective trial of pCLE during medical thoracoscopy to study and describe the malignant and benign pleural pCLE features.

Every patient >18 years referred to our department for medical thoracoscopy was eligible. Medical thoracoscopy was performed under sedation, allowing spontaneous breathing. Five millilitres of fluorescein (10%) was intravenously administrated 5 min before image acquisition. The pCLE was introduced through the working channel of the thoracoscope and gently placed on the parietal pleura to record videos. Afterwards, biopsies were performed on the corresponding sites. Malignant and benign pleural pCLE features were precisely described and compared using 11 preselected criteria.

A total of 62 patients were included in the analysis including 36 benign and 26 malignant pleura. Among our preselected criteria, 'abnormal tissue architecture' and 'dysplastic vessels' were strongly associated with malignancies (100% and 85% ss, 721% and 74% sp, respectively) whereas, the 'full chia seeds sign' and 'cell shape homogeneity' were associated with benignity (36% and 56% ss, 100% and 70% sp, respectively). No study-related adverse events occurred.

Benign and malignant pleural involvement have clearly distinct pCLE features.