A 72-year-old woman with lung cancer undergoes rigid bronchoscopy for tumor debulking. Post-procedure chest X-ray shows a wedge-shaped opacity in the left upper lobe with the hilum and mediastinum shifted toward the left. The left hemidiaphragm is elevated. There are no air bronchograms visible. What is the most likely radiological diagnosis?

## Radiological Diagnosis: Acute Lobar Collapse ### Classic Signs of Collapse (Atelectasis) **Key Point:** The triad of **mediastinal shift toward the lesion**, **elevated hemidiaphragm**, and **absence of air bronchograms** are hallmark features of lobar collapse. ### Consolidation vs Collapse: Differential Diagnosis | Finding | Consolidation | Collapse | |---------|---|---| | **Air bronchograms** | Present | Absent ✓ | | **Mediastinal shift** | None | Toward affected lobe ✓ | | **Hemidiaphragm** | Normal | Elevated ✓ | | **Hilum position** | Normal | Displaced toward lesion ✓ | | **Volume change** | Minimal | Decreased ✓ | | **Costophrenic angle** | Sharp | Blunted ✓ | ### Mechanism of Post-Procedure Collapse **High-Yield:** Rigid bronchoscopy can cause lobar collapse through: 1. **Airway obstruction** from tumor debris, blood clot, or mucus plugging 2. **Direct airway trauma** during instrumentation 3. **Aspiration** of secretions or foreign material **Clinical Pearl:** In the immediate post-operative period after bronchoscopy, acute collapse is more common than consolidation because the process is mechanical (obstruction) rather than inflammatory. ### Why This Is NOT Consolidation - **Absent air bronchograms:** Consolidation always shows air bronchograms; their absence rules out alveolar filling. - **Mediastinal shift and elevated hemidiaphragm:** These indicate volume loss, the hallmark of collapse, not consolidation. - **Wedge-shaped opacity:** While both can present as opacities, the associated signs of volume loss (shift, elevated diaphragm) point to collapse. ### Management Implications **Mnemonic: COLLAPSE MANAGEMENT = AIRWAY CLEARANCE** - **C**ough and deep breathing / incentive spirometry - **L**ateral positioning (affected side down) - **A**irway suctioning - **P**ositive pressure ventilation (if needed) - **S**urgical airway evaluation (if persistent) - **E**ndoscopic re-evaluation (if obstruction suspected) [cite:Felson's Principles of Chest Roentgenology Ch 3]