Molecular Testing on Pleural Fluid Samples.

Pleural effusions are a common manifestation of both malignant and nonmalignant diseases. The sampling of pleural fluid helps categorize effusions as transudative or exudative and helps differentiate paramalignant from malignant disease. Accurate pleural fluid analysis is critical to the appropriate staging of cancers with significant prognostic and treatment implications. However, the etiology of pleural effusions remains unclear in a significant number of cases after routine thoracentesis and pleural fluid analysis. For malignant pleural effusions, cytologic evaluation of pleural fluid has a relatively low sensitivity. We describe the evolving field of molecular pleural fluid analysis in the setting of malignant disease as an active area of investigation with both diagnostic and therapeutic implications.