A 2-year-old child presents with 3 weeks of fever, weight loss, cough, and a cervical lymph node of 2 cm. Mantoux test reads 16 mm. Chest X-ray shows hilar adenopathy with right middle lobe consolidation. Which MOST accurately describes the mechanism of this pulmonary finding?

• A Hematogenous dissemination of Mycobacterium tuberculosis to the lung parenchyma
• B Primary tuberculous pleural effusion tracking along the mediastinum into the lung parenchyma
• C Reactivation tuberculosis in a previously latent site in the right middle lobe
• D Compression of the right middle lobe bronchus by enlarged hilar lymph nodes causing collapse-consolidation ✓

Explanation

In primary childhood tuberculosis, the enlarged hilar and peribronchial lymph nodes can compress adjacent bronchi, most commonly the right middle lobe bronchus (due to its long length and acute branching angle)—causing collapse-consolidation of the right middle lobe. This is the mechanism of the 'epituberculosis' or collapse-consolidation seen in the Ghon complex. This is primary tuberculosis, not reactivation. Hematogenous dissemination causes miliary TB, not lobar collapse. Pleural tracking is not the mechanism here.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.