**Question:** Which of the following is not a feature of tuberculous pleural effusion?

A. Pleural thickening
B. Pleural effusion with loculations
C. Aspiration of purulent fluid
D. Pleural thickening without effusion

**Correct Answer: D (Pleural thickening without effusion)**

**Core Concept:** Tuberculous pleural effusion (TPE) is a common complication of extrapulmonary tuberculosis, characterized by the accumulation of fluid in the pleural space.

**Why the Correct Answer is Right:** Pleural thickening without effusion is not a feature of TPE, as it involves the accumulation of fluid in the pleural space, which is a defining characteristic of TPE. The presence of purulent fluid is also common in TPE, as it is typically an exudative effusion with high protein content and low glucose levels.

**Why Each Wrong Option is Incorrect:**

A. Pleural thickening: Pleural thickening is a common finding in tuberculous pleural effusion, as it is a result of inflammation and scarring caused by Mycobacterium tuberculosis infection.

B. Pleural effusion with loculations: Loculations occur when fluid-filled cavities or septa form within the pleural cavity, which is less specific to Tuberculous pleural effusion. Other causes, such as empyema, can also lead to loculated effusions.

C. Aspiration of purulent fluid: Aspiration of purulent fluid is a common feature of tuberculous pleural effusion, as it reflects the presence of a pathogenic infection in the pleural space.

**Clinical Pearl:** Tuberculous pleural effusion is a critical differential diagnosis for pleural effusions, especially in endemic areas, as appropriate treatment can significantly improve patient outcomes and prevent complications such as pleural fibrosis.

**Why Each Wrong Option is Incorrect:**

A. Pleural thickening: Pleural thickening is a more general feature of pleural fibrosis, which can be caused by several conditions, not just Tuberculous pleural effusion.

B. Pleural effusion with loculations: As explained above, loculations can be seen in pleural effusions due to various causes, not solely Tuberculous pleural effusion.

C. Aspiration of purulent fluid: Aspiration of purulent fluid is a common feature of Tuberculous pleural effusion, reflecting the presence of a pathogenic infection in the pleural space.

**Clinical Pearl:** Thoracentesis (aspiration of pleural fluid) should be considered in a differential diagnosis of pleural effusions, especially in endemic areas, as appropriate treatment can significantly improve patient outcomes and prevent complications such as pleural fibrosis.