What is a distinguishing feature of exudative pleural effusion?

• A. Low hyaluronidase levels
• B. High hyaluronidase levels
• C. No connection to cancer
• D. Associated with COPD

Answer: (B)

Exudative pleural effusions are characterized by the presence of high levels of proteins, inflammatory cells, and various enzymes within the pleural fluid. One of the distinguishing features is the elevated level of hyaluronidase. This enzyme, which is involved in breaking down hyaluronic acid found in connective tissues, is produced in higher quantities in conditions associated with inflammation, infection, or malignancy.

High hyaluronidase levels in the pleural fluid suggest an ongoing pathological process, such as infection (like pneumonia or tuberculosis), malignancy, or inflammatory diseases. In contrast, transudative effusions, which are often due to systemic causes such as heart failure or cirrhosis, typically exhibit low levels of protein and hyaluronidase, reflecting their non-inflammatory origin.

The other options do not accurately describe characteristics of exudative pleural effusions. Low hyaluronidase levels would suggest a transudative process. A lack of connection to cancer is misleading, as exudative effusions can arise from malignancies. Finally, while certain respiratory conditions like COPD may lead to transudative effusions due to heart failure, exudative effusions have a more complex etiology that can include inflammatory processes related