Breast, Chest Wall, and Thoracic Surgery Practice Test

Persistent unilateral pleural effusion that keeps reaccumulating after repeated drainage points to malignant involvement of the pleura. Cancer can infiltrate the pleural surfaces and obstruct lymphatic drainage, driving ongoing fluid production even after tapping. These effusions are typically exudative, and cytology may reveal malignant cells, with imaging often showing pleural thickening or nodularity.

By contrast, cardiogenic pleural effusions are usually bilateral and arise from elevated hydrostatic pressure in heart failure; they are transudative rather than exudative. A transudative effusion reflects systemic factors like CHF or hypoalbuminemia, not cancer, and empyema denotes an infected, pus-filled pleural space with signs of infection rather than ongoing malignant fluid production.