Tuberculous Lymphadenitis: Definition and Etiology

Tuberculous lymphadenitis, also known as scrofula, is a form of extrapulmonary tuberculosis that primarily affects the lymph nodes. It is the most common manifestation of tuberculosis outside the lungs and is often seen in regions with high tuberculosis prevalence.

Etiology

The condition is caused by Mycobacterium tuberculosis, the same bacterium responsible for pulmonary tuberculosis. It can also be caused by Mycobacterium bovis in rare cases. The infection typically spreads through hematogenous or lymphatic dissemination from a primary site of tuberculosis.

Pathogenesis

The disease progresses through several stages:

Initial Infection: Mycobacteria invade the lymph nodes, triggering an immune response.
Granuloma Formation: The immune system attempts to contain the infection by forming granulomas.
Caseous Necrosis: As the infection progresses, the affected lymph nodes undergo necrosis, leading to abscess formation.
Fibrosis and Healing: In some cases, the body successfully contains the infection, leading to fibrosis and resolution.

Clinical Presentation

Patients with tuberculous lymphadenitis typically present with:

Painless swelling of lymph nodes, commonly in the cervical region
Low-grade fever and night sweats
Weight loss and fatigue
Fluctuant lymph nodes in advanced cases

Diagnosis

Diagnosis is confirmed through a combination of clinical evaluation and laboratory tests:

Fine Needle Aspiration Cytology (FNAC): Identifies granulomas and acid-fast bacilli.
Polymerase Chain Reaction (PCR): Detects Mycobacterium tuberculosis DNA.
Chest X-ray: Assesses pulmonary involvement.
Culture and Histopathology: Confirms the presence of tuberculosis.

Treatment

The standard treatment follows the WHO-recommended regimen:

First-Line Anti-Tubercular Drugs: Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol.
Duration: Typically 6 months (2 months of intensive phase followed by 4 months of continuation phase).
Surgical Intervention: Considered in cases of abscess formation or non-resolving lymphadenopathy.