Exudative Pleural Effusions

1. Aetiology Exudative Pleural Effusions

2. What is an Exudate? A cloudy fluid containing proteins and cellular debris which has escaped from blood vessels and has been deposited in tissues, or on tissue surfaces, usually as a result of inflammation. • Transudative and exudative pleural effusions are distinguished by measuring the lactate dehydrogenase (LDH) and protein levels in the pleural fluid. • LDH is an enzyme which is important to the production of energy in cells. When cells die LDH is released and escapes into the blood. • Exudative pleural effusions meet at least one of the following criteria, whereas transudative pleural effusions meet none: • 1. pleural fluid protein/serum protein >0.5 • 2. pleural fluid LDH/serum LDH >0.6 • 3. pleural fluid LDH more than two-thirds normal upper limit for serum

3. Causes of Exudative Pleural Effusions • Parapneumonic causes • Malignancy (carcinoma, lymphoma, mesothelioma) • Pulmonary embolism • Collagen-vascular conditions (rheumatoid arthritis, lupus) • Tuberculous • Asbestos exposure   • Trauma • Postcardiac injury syndrome • Esophageal perforation • Radiation pleuritis • Drug use • Chylothorax Once an exudative pleural effusion has been established from the fluid test, the causes can be investigated. An exudative pleural effusion is not a pathology in itself and is always caused by something else such as:

4. Mesothelioma • Mesothelial cells are the superficial cells lining the lungs • They produce a transudate fluid to allow smooth movement of the lungs as they expand and contract whilst breathing • Mesothelioma causes pleural thickening that prevents lymphatic drainage of pleural fluid, causing fluid to build up- A pleural effusion • The Most common cause of mesothelioma is inhalation of asbestos fibres. • Asbestos fibres are very fine and once they have been inhaled they cannot be exhaled or coughed out

5. A Few Facts • Cancer research uk 2009 • 70-80% of people diagnosed with mesothelioma say they have been exposed to asbestos at some point in their life • Mesothelioma can not just affect the pleura but also the pericardium and peritoneum. • Pleural mesothelioma can spread to the pericardium quite easily due to the hearts close proximity to the pleural lining. • National Macmillan Mesothelioma Resource Centre 2008 • In the United Kingdom almost 2000 people a year are diagnosed with mesothelioma • Mesothelioma has a latency period meaning it can take from 15 to 45 years for asbestos to mesothelioma to occur and show any symptoms at all.

6. REFERENCES Goldberg, Persky and White (2009) ‘Mesothelioma Centre’ [Online rescource] available at:http://www.mesotheliomacenter.org/about/pleural-mesothelioma.php accessed 28/12/2009 Daniel L. Miller (2009) ‘Extrapleural Pneumonectomy’ CTSnet [online rescourse] Available at: http://www.ctsnet.org/sections/clinicalresources/thoracic/expert_tech-7.html accessed 2812/2009 Jeffrey Rubins (2009) ‘pleural effusion’ eMedicine [online rescource] Available at: http://emedicine.medscape.com/article/299959-overview accessed: 28/12/2009 National Macmillan Mesothelioma Resource Centre 2008 ‘mesothelioma uk’ [online rescource] available at http://www.mesothelioma.uk.com/index.php?pageno=18 accessed 28/12/2009 Cancer research UK 2009 ‘mesothelioma’ [online rescource] available at http://www.cancerhelp.org.uk/type/mesothelioma/index.htm accessed:28/12/2009 Victor L Roggli, thomas A Sporn and tim d ovry (2004) ‘pathology of asbestos associated disease’2nd Edition, springer, New York. Harvey I Pass, Nicholas J Vogelzang Michele Carbone (2005) ‘Malignant mesothelioma- advances in pathogenesis, diagnosis and translational therapies’ Springer, New York