All of the following are indirect radiologic signs of collapse of lung EXCEPT –
**Core Concept**
The question is testing the ability to identify indirect radiologic signs of lung collapse, which are subtle changes in the surrounding lung tissue and mediastinal structures that indicate loss of lung volume. These signs are essential for diagnosing conditions like atelectasis, pneumonia, or pulmonary embolism.
**Why the Correct Answer is Right**
Indirect radiologic signs of lung collapse include:
* **Shift of the mediastinum**: The trachea, main bronchi, and mediastinal structures are displaced away from the collapsed lung due to the increased volume of the remaining lung tissue.
* **Decreased volume of the hemithorax**: The affected hemithorax appears smaller due to the loss of lung volume.
* **Increased opacity of the surrounding lung**: The remaining lung tissue becomes more opaque due to the increased density of the alveoli.
* **Obstruction of the major bronchi**: The collapsed lung may cause obstruction of the major bronchi, leading to increased opacity of the affected area.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not an indirect radiologic sign of lung collapse. However, without knowing the actual option, we can't explain why.
* **Option B:** This option might be incorrect if it is a direct radiologic sign of lung collapse, such as the "silhouette sign" or "air bronchogram sign".
* **Option C:** This option might be incorrect if it is a radiologic sign of something else, such as a pleural effusion or a pneumothorax.
**Clinical Pearl / High-Yield Fact**
When interpreting chest radiographs, remember that indirect radiologic signs of lung collapse can be subtle and require careful observation. Pay attention to changes in the mediastinal structures, lung volume, and surrounding lung tissue to avoid missing these critical signs.
**Correct Answer:** D.