Mini-Invasive Pleural Probe-Based Confocal Laser Endomicroscopy for Malignant Pleural Effusion Diagnosis

Introduction: Probe-based confocal laser endomicroscopy (pCLE) is an optical imaging tool which allows live imaging tissues at cellular level. pCLE proved to be able to discriminate malignant from benign pleura during medical thoracoscopy and can identify malignant cells in pleural fluids. Since pleural fluid cytology has limited sensitivity for malignant pleural effusion diagnosis, we wanted do determine the feasibility, the safety, and the yield of mini-invasive close-blinded pleural pCLE.

We conducted a single-center prospective trial. Every patient referred to medical thoracoscopy because of pleural effusion was eligible. Thoracocentesis for pleural fluid analysis was performed first with a Boutin's needle. Second, the probe was introduced in the pleural space through the Boutin's needle for mini-invasive pleural pCLE. Finally, the medical thoracoscopy and invasive pleural pCLE were performed. Seven pCLE criteria were prospectively rated to assess the sensitivity and specificity of mini-invasive pleural pCLE for malignant pleural effusion diagnosis.

Fifty-two patients were enrolled. Mini-invasive pleural pCLE was feasible and safe. Pathological pleural fluid analysis identified malignant effusion with 42% sensitivity and 100% specificity. For the mini-invasive pleural pCLE, five of 7 criteria proved to be significantly discriminant between malignant and benign pleura. Overall, mini-invasive pleural pCLE had 87% sensitivity for malignant pleural effusion identification. The specificity is 52%, and the positive and negative predictive value were 73% both.

Mini-invasive pleural pCLE was safe and feasible and its sensitivity for malignant pleural infiltration diagnosis was much higher than pleural fluid cytology.