A18.4

Clinical Causes: Mycobacterium tuberculosis bacteria spreading from the lungs or other infected sites through the bloodstream or lymphatic system Infection through direct contact with an individual who has active, contagious tuberculosis Reactivation of dormant tuberculosis bacteria within the skin tissues Less commonly, through contaminated medical equipment or skin injuries Associated conditions such as lupus vulgaris, scrofuloderma, or erythema induratum may influence the presentation

Key Symptoms: Chronic skin nodules or ulcers that may be firm or indurated Localized swelling, redness, or inflammation, especially around affected areas Discoloration of the skin, sometimes showing a reddish or bluish hue Formation of abscesses or discharging ulcers in certain cases Possible involvement of eyelids, external ears, or other specific regions depending on the type Signs of systemic illness like fever, weight loss, or fatigue are less common but can occur

Diagnosis Path: The diagnosis often involves a combination of clinical examination, histopathology, and microbiological tests. Skin biopsies are examined microscopically for granulomatous inflammation, and cultures or molecular tests like PCR can identify Mycobacterium tuberculosis. Imaging studies or chest X-rays may be used to detect concurrent tuberculosis in other parts of the body. A positive tuberculin skin test or interferon-gamma release assay can support the diagnosis, but are not definitive alone.

Treatment Protocols: Treatment typically includes a prolonged course of multi-drug anti-tuberculosis therapy, following standard guidelines. This usually involves a combination of antibiotics such as isoniazid, rifampicin, ethambutol, and pyrazinamide over several months. Management may also include supportive care like wound cleaning and preventing secondary infections. Close monitoring for drug side effects and treatment adherence is essential to ensure successful resolution.