Non randomized study with two groups. The study group includes patients with suspected malignant pleural effusion, in whom the investigation of pleural effusion begins directly with pleural biopsy by Local Anesthesia Thoracoscopy (LAT). The Control Group includes patients who come to the same hospital and are treated with the Standard of Care (SOC) strategies were used. Efficacy of LAT, Sensitivity, Hospitalization, time to diagnosis and general safety and comfort of the groups' subjects will be assessed.