Plevritis (pleurisy) is a serious condition. It could be life-threatening if the pleural drain is massive and disturbs lung function. In cases of massive pleural drain, an emergency procedure (pleural drainage) is performed. It is very important to find out the reason for your pleurisy. The most common reasons are lung inflammation (pneumonia) and lung cancer. An X-ray image of the lungs detects pleural drain but it could also detect its origin. An X-ray, blood picture, pleural punition and microbiological examinations are ample diagnostic procedures for identifying pneumonia. If there are suspicions that lung cancer is present, a bronchoscopic biopsy and a thoracic CT-scan can be performed.