Miliary tuberculosis
Summary
Miliary tuberculosis is widespread haematogenous dissemination of Mycobacterium tuberculosis producing innumerable small granulomas throughout the lungs and other organs. The chest radiograph shows a diffuse pattern of tiny nodules resembling millet seeds, from which the name derives.
Detail
Dissemination follows erosion of a tuberculous focus into a pulmonary vein or lymphatic, seeding organs with high blood flow: lungs, liver, spleen, bone marrow, kidneys, adrenals, and meninges. It occurs either during progressive primary infection, typically in infants and young children, or on reactivation in the immunosuppressed, the elderly, and patients on TNF-alpha inhibitors, which is why screening for latent tuberculosis is mandatory before starting infliximab or similar agents. Presentation is often insidious with fever, night sweats, weight loss, and a normal or near-normal early chest film; choroidal tubercles on funduscopy are highly suggestive. The tuberculin skin test is frequently falsely negative because of anergy. Complications include tuberculous meningitis, which characteristically involves the basilar meninges causing cranial nerve palsies and hydrocephalus, and adrenal involvement causing Addison disease. Treatment is standard four-drug therapy with rifampin, isoniazid, pyrazinamide, and ethambutol, extended in duration for meningeal disease, with adjunctive corticosteroids for meningitis and pericarditis.
Sources
- Harrison's Principles of Internal Medicine
- Robbins Basic Pathology
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