## Radiological Signs of Pneumothorax ### Correct Findings (Options 0, 1, 3) **Key Point:** The visceral pleural line is the cardinal sign of pneumothorax — a thin, sharp, white line representing the edge of the collapsed lung, with absent lung markings (bronchial and vascular) peripheral to it. **High-Yield:** In supine patients, the **deep sulcus sign** (hyperlucency in the costophrenic angle) is more sensitive than the visceral pleural line and is a key sign to recognize pneumothorax on portable chest radiographs. ### Why Option 2 is WRONG **Warning:** The **hilum sign (mediastinal shift toward the pneumothorax side) indicates SIMPLE pneumothorax, NOT tension pneumothorax.** This is a critical distinction. **Clinical Pearl:** Tension pneumothorax shows the opposite — mediastinal shift AWAY from the pneumothorax side (toward the normal lung), along with: - Compression of the ipsilateral heart and great vessels - Flattening or inversion of the ipsilateral hemidiaphragm - Contralateral mediastinal displacement ### Summary Table | Sign | Finding | Significance | | --- | --- | --- | | Visceral pleural line | Thin white line at lung edge | Diagnostic of pneumothorax | | Absent lung markings | No bronchial/vascular markings beyond pleural line | Confirms pneumothorax | | Deep sulcus sign | Hyperlucency in costophrenic angle (supine) | Sensitive in supine patients | | Hilum sign | Mediastinal shift TOWARD pneumothorax | Simple pneumothorax | | Mediastinal shift AWAY | Shift toward normal lung | Tension pneumothorax (emergency) | [cite:Felson's Principles of Chest Roentgenology Ch 8]
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