To date, the different biopsy methods, such as CT-guided pleural biopsy, mediastinal biopsy, endosonography and thoracoscopy have their limitations in diagnosing pleural malignancies, such as mesothelioma. Sampling errors frequently occur resulting in the common histological finding of 'non-specific pleuritic/fibrosis', which presents a great uncertainty for clinicians and patients. Confocal laser endomicroscopy (CLE) provides real-time imaging on a cellular level, however data of CLE in pleural malignancies are lacking.

Novel optical imaging techniques such as confocal laser endomicroscopy (CLE) have emerged in recent years as techniques that actually enable in vivo real-time microscopic analysis of malignancies of the GI-tract and lung cancer. Through recent advances the probe became small enough to fit through a biopsy needle and can be used during CT-guided and endosonographic guided biopsies (EUS-FNA). Patients with intra-thoracic malignancies often require invasive procedures such as bronchoscopy, thoracoscopy, mediastinoscopy, transthoracic needle aspiration or surgical exploration to obtain a diagnosis. Intra thoracic malignancies encompass lung cancers, thymomas and malignant pleural mesothelioma. These tumors often present with pleural thickening, unilateral pleural effusion, mediastinal enlargement or a peripheral located mass in the lungs. Tissue collection of the suspected pleural thickening is required to assess a diagnosis and differentiate between the tumor types, to classify and to stage in a proper manner. To date, the different biopsy methods, such as CT-guided pleural biopsy, mediastinal biopsy, endosonography and thoracoscopy have their limitations in diagnosing these malignancies. Sampling errors frequently occur resulting in the common histological finding of 'non-specific pleuritic/fibrosis', which presents a great uncertainty for clinicians and patients. Novel microscopic imaging techniques such as CLE are capable of real time imaging on a cellular level. Data of CLE in intra-thoracic malignancies are lacking.

Inclusion Criteria:

• ≥18 years of age
• Supected intra-thoracic malignancies with pleural involvement and referred for a diagnostic procedure by thoracoscopy, CT guided biopsy or endosonography

Exclusion Criteria:

• Inability and willingness to provide informed consent
• Patients with known allergy for fluorescein or risk factors for an allergic reaction
• pregnancy or lactating women

Patients with suspected intra-thoracic malignancies, who are referred for diagnostic work-up by either transthoracic, thoracoscopic or endosonographic biopsy.

CLE imaging