Primary tuberculous lymphadenitis

Primary tuberculous lymphadenitis, also known as tuberculous peripheral lymphadenopathy or scrofula, is an extrapulmonary form of tuberculosis in which Mycobacterium tuberculosis (or occasionally other mycobacteria of the M. tuberculosis complex) primarily infects the lymph nodes without significant pulmonary involvement. It is the most common form of extrapulmonary tuberculosis worldwide. The disease predominantly affects the lymphatic system, with cervical (neck) lymph nodes being the most frequently involved, although axillary, inguinal, and mediastinal nodes may also be affected. Patients typically present with slowly enlarging, painless or mildly tender lymph node swelling that may be unilateral or bilateral. Over time, affected nodes may become matted together, form cold abscesses, or develop draining sinus tracts to the skin surface. Constitutional symptoms such as low-grade fever, night sweats, weight loss, and fatigue may or may not be present. The condition is more common in immunocompromised individuals, including those with HIV infection, but can also occur in immunocompetent persons, particularly in endemic regions. Diagnosis is established through a combination of clinical evaluation, fine-needle aspiration cytology or excisional biopsy showing granulomatous inflammation (often with caseating necrosis), acid-fast bacilli staining, mycobacterial culture, and molecular testing such as PCR. Tuberculin skin testing and interferon-gamma release assays may support the diagnosis. Treatment follows standard anti-tuberculous chemotherapy, typically consisting of a multi-drug regimen including isoniazid, rifampicin, pyrazinamide, and ethambutol for an initial intensive phase of two months, followed by a continuation phase of isoniazid and rifampicin for four additional months. Surgical excision may be considered in cases that are refractory to medical therapy or when diagnostic tissue is needed. With appropriate treatment, the prognosis is generally excellent, though paradoxical reactions (temporary worsening of lymph node swelling after starting therapy) may occur.

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