Key Points

• Diagnosis of pleural diseases is based on a comprehensive history and physical examination.
• Simple, minimally invasive techniques such as thoracentesis can provide fluid, cells, and tissue for analysis, which lead to diagnosis in the majority of cases.
• VATS or pleuroscopy can aid in diagnosis when less invasive techniques fail to yield a diagnosis. More invasive procedures such as thoracotomy are rarely required.

Diseases of the pleural space are common in a thoracic surgical practice, and although their management may seem simple, their diagnosis often presents a challenge. In patients presenting with pleural problems, a thorough history and physical examination remain the basis for the physician’s initial assessment and differential diagnosis. Radiography is helpful in providing clues to a diagnosis by distinguishing between pleural fluid and a mass and by allowing evaluation of the adjacent lung and pleura. A definitive diagnosis, however, usually requires a diagnostic procedure to provide fluid, cells, or tissue for analysis and microscopic review. This chapter reviews the range of pleural diseases in relation to the diagnostic procedures, their indications, and techniques.

Although a wide range of diseases can involve the pleura and the pleural space, these can be narrowed down to two forms: pleural fluid and pleural mass or masses (Table 1). Pleural effusions are the most common disturbances of the pleural space. Effusions may be secondary to increased capillary permeability (inflammation, infection, tumor implants); decreased oncotic pressure (liver failure, malnutrition); increased hydrostatic pressure (congestive heart failure, renal failure); increased intrapleural pressure (atelectasis); or decreased lymphatic drainage (carcinomatosis, tumor compression, radiation). Often, the effusion results from a combination of mechanisms. As a result, these processes produce fluid that may be serous, sanguineous, chylous, or purulent. Less commonly, a solid process or tumor may involve the pleural surfaces. Masses in the pleural lining are predominantly malignant. Of these, secondary malignancies are more common, most frequently from lung, breast, ovarian, or gastrointestinal primaries. Primary malignancies of the pleura and mesothelioma are seen with increasing frequency, and most cases are related to a remote asbestos exposure. Benign lesions of the pleural surface may be pleural plaques. Solitary fibrous tumors, previously called benign pleural mesothelioma, generally have indolent behaviour but may have malignant elements particularly if large..