Tuberculous Lymphadenitis (Scrofula)

Tuberculous lymphadenitis is an infection of lymph nodes caused by Mycobacterium tuberculosis (or rarely M. bovis from unpasteurized dairy), representing 30-40% of extrapulmonary tuberculosis cases globally and the most common extrapulmonary site. The cervical chain is involved in 60-90% of cases (historically termed scrofula or 'King's evil'), followed by mediastinal, axillary, mesenteric, and inguinal nodes. Pathogenesis involves hematogenous or lymphatic dissemination from a primary pulmonary or oropharyngeal focus, with subsequent granulomatous inflammation, caseous necrosis, and potential cold abscess formation.

Clinical presentation is typically indolent: painless, firm, slowly enlarging lymph node(s) over weeks to months, often unilateral, eventually becoming matted (multiple nodes adherent to each other), then fluctuant (cold abscess), and finally rupturing through skin to form chronic discharging sinus tracts. Systemic 'B symptoms' (fever, night sweats, weight loss, malaise) are present in less than 50%, particularly in immunocompetent patients. HIV coinfection alters presentation with more disseminated disease, multifocal involvement, and atypical features.

Diagnostic workup includes detailed history (TB exposure, country of origin, BCG status, HIV risk factors), tuberculin skin test or IGRA (positive in 80-90%), chest imaging (active or healed pulmonary TB in 30-40%), and tissue diagnosis via fine-needle aspiration (FNA — first-line) with AFB smear, mycobacterial culture (gold standard, takes 6-8 weeks), Xpert MTB/RIF (rapid PCR with rifampin resistance detection), and histopathology (caseating granulomas with Langhans giant cells). Excisional biopsy is reserved for cases with non-diagnostic FNA. Treatment is standard 6-month regimen (2 months of RIPE: rifampin, isoniazid, pyrazinamide, ethambutol; followed by 4 months of RH), with longer regimens for drug-resistant TB, central nervous system involvement, or HIV coinfection. Paradoxical reactions (worsening of lymphadenopathy during treatment) occur in 20-30% and may require corticosteroids.