According to RNTCP surveillance data, which is the most common site of extrapulmonary tuberculosis reported in India?

Explanation

## Most Common Site of Extrapulmonary TB in RNTCP **Key Point:** Lymph node tuberculosis (TB lymphadenitis) is the most frequent form of extrapulmonary TB reported under RNTCP surveillance, accounting for approximately 40–50% of all extrapulmonary TB cases in India. ### Epidemiological Profile | Site | Frequency in RNTCP | Clinical Features | | --- | --- | --- | | **Lymph node TB** | 40–50% | Painless, progressive lymphadenopathy; often cervical | | Abdominal TB | 15–20% | Peritoneal, mesenteric involvement; ascites | | Skeletal TB | 10–15% | Spine (Pott's disease), hip, knee | | TB meningitis | 5–10% | Acute/subacute CNS infection; high mortality | | Pleural TB | 5–10% | Pleural effusion; often with pulmonary TB | ### Why Lymph Node TB Is Most Common 1. **Hematogenous dissemination** — bacilli lodge in regional lymph nodes during primary TB 2. **Ease of diagnosis** — lymph node biopsy/FNA is accessible; AFB smear/culture often positive 3. **Lower virulence requirement** — does not require severe immunosuppression (unlike TB meningitis) 4. **Age distribution** — common in children (primary TB) and adults with recent infection ### Clinical Presentation **High-Yield:** Cervical lymphadenopathy is the most common presentation of lymph node TB in India. Nodes are: - Painless, rubbery, matted - May show caseation and sinus formation - Often unilateral or bilateral ### Diagnostic Approach Under RNTCP 1. **Clinical examination** — palpable cervical/axillary nodes 2. **Imaging** — Chest X-ray (hilar nodes), ultrasound, CT 3. **Confirmation** — FNA cytology (caseating granuloma), culture, GeneXpert MTB/RIF 4. **Treatment** — Standard 6-month anti-TB regimen (same as pulmonary TB) **Clinical Pearl:** Lymph node TB may present as the sole manifestation of TB disease or coexist with pulmonary TB. In children, it is often the only sign of primary TB. ### Why Other Sites Are Less Common - **TB meningitis:** Occurs in ~5–10% of extrapulmonary TB; requires hematogenous spread to meninges; high mortality and morbidity; less frequent than lymph node involvement - **Abdominal TB:** Represents 15–20% of extrapulmonary TB; requires ingestion or hematogenous spread to GI tract and peritoneum; less accessible for diagnosis - **Skeletal TB:** Accounts for 10–15% of extrapulmonary TB; usually involves spine (Pott's disease); requires direct hematogenous seeding to bone