A 28-year-old woman with a history of TB contact is found to have a right upper lobe infiltrate on screening chest X-ray. Review of her imaging shows all of the following radiological patterns EXCEPT which one is commonly seen in endobronchial tuberculosis?

## Endobronchial Tuberculosis: Radiological Patterns ### Definition and Pathophysiology **Key Point:** Endobronchial TB (EBTB) is infection of the bronchial mucosa and submucosa, causing airway obstruction, stenosis, and collapse of distal lung segments. It represents 10–15% of pulmonary TB cases. ### Characteristic Radiological Findings in EBTB | Feature | Present in EBTB | Mechanism | |---------|-----------------|----------| | Segmental/lobar collapse | Yes | Airway obstruction by granulation tissue/stenosis | | Minimal parenchymal consolidation | Yes | Collapse without extensive infiltration | | Bronchial wall thickening/stenosis (CT) | Yes | Direct mucosal inflammation and fibrosis | | Peripheral wedge-shaped consolidation | Yes | Distal parenchymal involvement from endobronchial spread | | Air bronchogram | Yes | Patent airways within consolidated distal lung | | Preserved bronchial patency on bronchoscopy | No | Hallmark finding is LOSS of patency due to stenosis | ### Why Option 3 (Atelectasis with Preserved Bronchial Patency) Is Wrong **High-Yield:** The defining feature of endobronchial TB is **bronchial obstruction and stenosis**. If bronchial patency is preserved on bronchoscopy, the collapse is not due to endobronchial disease — it would indicate parenchymal disease or other causes of atelectasis (pleural effusion, mass, etc.). **Clinical Pearl:** On bronchoscopy in EBTB, you see: - Granulation tissue and ulceration - Stenosis and narrowing of the bronchial lumen - Caseous material - **Loss of normal bronchial patency** — this is the hallmark. If the bronchus is patent, the collapse is not endobronchial in origin. ### Correct Findings in EBTB 1. **Segmental/lobar collapse with minimal consolidation** — obstruction of segmental bronchus causes distal atelectasis without extensive infiltration. 2. **Bronchial wall thickening and stenosis on CT** — direct visualization of airway involvement; highly specific for EBTB. 3. **Peripheral wedge-shaped consolidation with air bronchogram** — distal parenchymal involvement with patent airways within the consolidation.