Clinical History
A 74-year-old man presented with worsening shortness of breath, hemoptysis, 20 kg weight loss, night sweats, and chronic cough. He recently moved from a TB-endemic country. Exam showed hypoxia, tachypnoea, bilateral crepitations, and dullness at the left lung base. Quantiferon Gold test positive. Chest X-ray revealed bilateral nodules and left basal pneumonia. He died from respiratory failure soon after admission.

Pathology
The right lung showed many small pale-yellow nodules (tubercles) scattered throughout the parenchyma and subpleural areas—typical of miliary tuberculosis. Bronchi were mildly dilated.

Further Information
Tuberculosis (TB) is a chronic infection caused by Mycobacterium tuberculosis, spread by inhalation of droplets. Risk factors include living in endemic areas, immunosuppression, chronic lung disease, alcoholism, and malnutrition.

90% develop latent TB, which can reactivate. 10% (especially immunocompromised) get primary active TB with pulmonary and extrapulmonary symptoms.

Secondary TB is latent TB reactivation, causing cough, hemoptysis, fever, night sweats, and weight loss.

Miliary TB occurs when bacteria spread hematogenously, seeding lungs and other organs.

Immunity involves TH1 cells activating macrophages, forming granulomas with caseous necrosis. Disease may heal with fibrosis or progress to cavitation and hemoptysis.

Diagnosis uses history, chest X-ray, sputum culture, Mantoux, and interferon gamma tests. Treatment requires long-term multi-drug antibiotics.