ABSTRACT
The clinical recognition of a pleural effusion, either on physical examination or radiologically, as a marker of an abnormal physiological state has resulted in greater formation than removal of pleural fluid. Disease in virtually any organ system can be the cause of a pleural effusion (1). In the approach to the patient with a pleural effusion, the clinician must be cognizant that not only can disease in the thorax be causative, but disease of organs juxtaposed to the diaphragm, such as the liver or spleen, can as well. Furthermore, systemic diseases, such as systemic lupus erythematosus and rheumatoid arthritis, may involve the pleura, as can diseases of the lymphatic system, such as yellow nail syndrome. Therefore, the evaluation of a pleural effusion must begin with a complete history and physical examination and follow with pertinent laboratory tests to formulate a prethoracentesis diagnosis.
