A 6-year-old child from rural India presents with a 3-month history of cough and fever. Chest X-ray shows hilar lymphadenopathy with minimal parenchymal involvement. Tuberculin skin test (TST) is negative. Which feature best distinguishes primary progressive tuberculosis from progressive primary TB with endobronchial disease?

Explanation

## Discriminating Feature: Endobronchial Involvement ### Primary Progressive TB vs. Endobronchial TB **Key Point:** Endobronchial tuberculosis (EBT) is a specific manifestation of primary TB in children characterized by direct invasion of the bronchial wall by caseous material from adjacent lymph nodes, leading to airway obstruction. ### Comparison Table | Feature | Primary Progressive TB | Endobronchial TB | | --- | --- | --- | | **Lymph node involvement** | Hilar/mediastinal | Hilar/mediastinal (eroding into bronchus) | | **Parenchymal disease** | Progressive consolidation | Distal atelectasis/collapse | | **Cavitation** | Rare in children <5 yrs | Rare in children | | **Airway obstruction** | Absent | **Present (hallmark)** | | **TST status** | Often negative initially | Often negative initially | | **Clinical presentation** | Fever, cough, weight loss | Persistent cough, wheezing, stridor, lobar collapse | **High-Yield:** Endobronchial TB is the **best discriminator** because it represents direct erosion of a caseating lymph node into the bronchial lumen, causing: - Segmental/lobar atelectasis (collapse) - Bronchial stenosis - Recurrent lower respiratory tract infections - Persistent cough despite anti-TB therapy if stricture develops **Clinical Pearl:** In a child with TB and sudden onset of wheezing or stridor, or lobar collapse on imaging, suspect endobronchial disease. This requires bronchoscopy for confirmation and may need endoscopic intervention (balloon dilation, stent placement) in addition to chemotherapy. **Warning:** Do not confuse endobronchial TB with miliary TB (hematogenous dissemination). Endobronchial TB is a **local airway complication** of primary TB lymphadenitis, not a disseminated form. [cite:Park 26e Ch 8]