## Extrapulmonary TB in Children: Site Distribution **Key Point:** Hilar and mediastinal lymphadenitis is the most common form of extrapulmonary TB in children, accounting for approximately 40–50% of all pediatric TB cases. ### Why Hilar/Mediastinal Lymphadenitis Predominates Children have immature immune systems and develop primary TB following initial infection. The bacilli lodge in the regional lymph nodes draining the site of entry (usually lungs via inhalation). These nodes enlarge and may cause: - Bronchial compression and atelectasis - Bronchial obstruction leading to hyperinflation - Rarely, erosion into bronchi (broncholiths) ### Frequency of Extrapulmonary TB Sites in Children | Site | Frequency | Clinical Significance | | --- | --- | --- | | Hilar/mediastinal lymphadenitis | 40–50% | Most common; often asymptomatic | | Tuberculous meningitis | 10–15% | Most serious; high mortality if untreated | | Skeletal TB (spine, long bones) | 5–10% | Subacute; may cause deformity | | Tuberculous peritonitis | 3–5% | Ascites, abdominal distension | | Miliary TB | 1–3% | Acute dissemination; poor prognosis | **High-Yield:** Lymphadenitis in primary TB is often self-limited and may resolve without specific treatment, whereas disseminated forms (meningitis, miliary) require urgent chemotherapy. **Clinical Pearl:** Hilar lymphadenitis in a child with a positive tuberculin skin test (TST) and no respiratory symptoms is often diagnosed incidentally on chest X-ray and represents primary TB complex. **Mnemonic:** **HELM** — Hilar/mediastinal Extrapulmonary is the Largest/most common in pediatric TB.
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