A 62-year-old woman with lung cancer undergoes bronchoscopy for biopsy. Post-procedure, she develops acute dyspnoea. Chest X-ray shows opacification of the right upper lobe with the right heart border remaining visible. The right hilum is elevated, and the trachea is shifted rightward. The right upper lobe appears smaller in volume compared to the left. What is the primary radiological finding?

Explanation

## Radiological Diagnosis: Collapse (Atelectasis) with Mediastinal Shift **Key Point:** The combination of volume loss (elevated hilum, smaller lobe, rightward tracheal shift) with opacification indicates collapse, not consolidation. Collapse results from bronchial obstruction or loss of elastic recoil, causing alveolar air to be resorbed. **High-Yield:** Mediastinal shift TOWARD the lesion = collapse. Mediastinal shift AWAY from the lesion = large effusion or tension pneumothorax. Volume loss is the hallmark of collapse. ### Classic Signs of Collapse | Sign | Mechanism | Appearance | |------|---|---| | **Mediastinal shift toward lesion** | Loss of volume pulls structures | Trachea, heart shift to affected side | | **Elevated hilum** | Lobe shrinks vertically | Hilum higher than contralateral side | | **Decreased hemithorax volume** | Alveolar air resorbed | Lobe appears smaller, crowded vessels | | **Silhouette sign** | Loss of normal borders | Heart/mediastinal border obscured if adjacent | | **Absence of air bronchograms** | Bronchi are obstructed | No lucent lines within opacity | **Clinical Pearl:** Post-bronchoscopy collapse is common due to mucus plugging or bronchial edema causing obstruction. The rightward tracheal shift and elevated right hilum are cardinal signs of right upper lobe collapse. ### Pathophysiology of Collapse 1. Bronchial obstruction (mucus plug, tumour, oedema) or loss of elastic recoil 2. Alveolar air is resorbed into pulmonary capillaries 3. Loss of air volume → lobe shrinks 4. Mediastinal structures shift toward the collapsed lobe 5. No new air enters → no air bronchograms **Mnemonic:** **SLIM** = **S**hift toward lesion, **L**oss of volume, **I**ncreased density, **M**ediastinal shift **Warning:** Do not confuse collapse with consolidation. Consolidation has air bronchograms and NO volume loss. Collapse has NO air bronchograms and marked volume loss with mediastinal shift. ### Differential: Why Not Consolidation? Consolidation would show: - Air bronchograms (absent here) - Normal or increased hemithorax volume (volume is decreased here) - No mediastinal shift (shift is present here) - No elevation of hilum (hilum is elevated here)