[Diagnosis of pleurisy].

Diagnosis of pleural effusion, suggested by chest pain or dyspnea, is assessed by physical examination, chest X-ray sometimes completed by other imaging techniques, and mainly by thoracentesis. Thoracentesis is mandatory for the diagnostic of pleural effusion as three diagnosis are associated with an emergency treatment: pulmonary embolism; hemothorax; empyema. If the fluid is a transudate, no further invasive studies are necessary. If the cause of pleural exsudat cannot be established by a careful history, physical examination and fluid analysis, generally closed pleural biopsy should be done, followed, in absence of an established diagnosis, by thoracoscopy. At this time, less than 10% of the cases remain without explanation, leading to a careful follow-up of patients since a carcinomatous lesion may develop in 1/3 of them.