ABSTRACT
The vast majority of pleural effusions in the United States, as in many parts of the world, are caused by congestive heart failure, pulmonary infections, malignancy, and pulmonary embolism. These are common disease processes, especially in older populations. Therefore, distinguishing benign from malignant pleural effusions is a common challenge in the practice of chest medicine and is of wide interest to many physicians and their patients. The intent of this chapter is to summarize methods, both proven and experimental, for achieving this goal. For the purposes of this discussion, we define malignant effusion in a broad sense to include any pleural effusion associated with malignancy by cytology, pleural biopsy, or autopsy as well as those effusions associated with a known malignancy with no other explanation for their formation, even in the absence of positive fluid cytology, pleural biopsy, or autopsy (some authors prefer to call these paramalignant effusions). Benign effusions are pleural effusions arising from all other disease processes.
