## Extrapulmonary TB Sites — Frequency Distribution **Key Point:** Lymph node TB (tuberculous lymphadenitis) is the most common form of extrapulmonary tuberculosis, accounting for approximately 40–50% of all extrapulmonary TB cases in India. ### Epidemiological Pattern The frequency of extrapulmonary TB sites in descending order: | Site | Frequency (%) | Clinical Features | |------|---------------|-------------------| | **Lymph node (TB lymphadenitis)** | **40–50** | **Painless, mobile, matted lymph nodes; often cervical** | | Pleural TB | 15–20 | Pleural effusion, chest pain, cough | | Abdominal TB | 10–15 | Ascites, peritonitis, intestinal strictures | | Skeletal TB | 8–10 | Spine (Pott's disease), hip, knee | | TB meningitis | 5–8 | Acute/subacute meningitis, high mortality | | Genitourinary TB | 3–5 | Hematuria, dysuria | | Other sites | <5 | Pericardial, cutaneous, ocular | **High-Yield:** In India, TB lymphadenitis is the single most common extrapulmonary presentation, particularly in children and young adults. It is often seen with or without concurrent pulmonary TB. ### Clinical Pearl **Key Point:** Cervical lymphadenitis ("scrofula") is the most frequent presentation of TB lymphadenitis. Diagnosis is confirmed by fine-needle aspiration cytology (FNAC) showing caseating granulomas or TB culture. ### Why Other Sites Are Less Common - **TB meningitis** (5–8%): Serious but relatively rare; occurs early in primary TB or reactivation TB. - **Abdominal TB** (10–15%): More common in endemic areas but still less frequent than lymph node involvement. - **Skeletal TB** (8–10%): Pott's disease (spinal TB) is the most common skeletal manifestation but overall accounts for <10% of extrapulmonary TB. [cite:Park 26e Ch 7]
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