## Most Common Site of Extrapulmonary TB in RNTCP **Key Point:** Lymph node tuberculosis (TB lymphadenitis) is the most common form of extrapulmonary TB, accounting for 40–50% of all EPTB cases in India. ### Epidemiology of EPTB Sites | Site | Frequency (%) | Clinical Features | | --- | --- | --- | | Lymph node | 40–50 | Painless, mobile, matted nodes; cervical > axillary | | Pleural | 15–20 | Pleural effusion; chest pain; breathlessness | | Abdominal | 10–15 | Ascites, pain, obstruction; peritoneal/intestinal involvement | | Meningeal | 5–10 | Severe; high mortality; CSF lymphocytosis | | Bone & joint | 5–10 | Pott's disease (spine), TB arthritis | | Genitourinary | 3–5 | Hematuria, dysuria | | Other (pericardial, cutaneous) | <5 | Rare | **Clinical Pearl:** TB lymphadenitis is often the first manifestation of TB in children and immunocompromised individuals (including HIV+). It may occur with or without pulmonary involvement. ### Why Lymph Node TB is Most Common 1. **Anatomical proximity:** Lymph nodes are the first line of immune defense; mycobacteria lodge here early 2. **Hematogenous dissemination:** Occurs early in primary TB, especially in children 3. **Diagnosis:** More readily accessible for biopsy and culture compared to deep organs 4. **Reporting bias:** RNTCP surveillance captures lymph node cases more easily than occult abdominal TB **High-Yield:** Under RNTCP, EPTB cases are notified separately and tracked. Lymph node TB is the gateway diagnosis for identifying TB in the community. **Mnemonic: LEAP** — **L**ymph node (most common), **E**ssudative pleural, **A**bdominal, **P**ulmonary (in order of EPTB frequency) **Warning:** Do not confuse "most common EPTB site" with "most severe EPTB." Meningeal TB is rare but has the highest mortality and morbidity. [cite:Park 26e Ch 9]
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