Pathology - Tuberculosis

Pathology - Tuberculosis
inhalation of mycobacterium tuberculosis-containing droplets

Pathophysiology: Alveolar macrophages phagocytose tuberculosis (TB) bacilli. triggering an immunological response mediated by T cells. The majority of bacilli are destroyed by macrophages and T lymphocytes, but some remain and lie latent in the Ghon complex (primary TB). The activation of these organisms occurs through immunosuppression or reinfection (secondary TB).Meningitis and Pott disease of the spine are examples of extrapulmonary TB symptoms. Tuberculosis (TB) can also spread through lymphatics or blood, resulting in miliary TB, or the seeding of distal organs.
First-line TB: Ghon complex: increased caseous hilar vmph nodes (calcified lesion in upper half of lower lobe).
Secondary tuberculosis (TB): Caseating granuloma composed of epithelioid cells; tubercle development (cavitary lesion) at lung apex or hilar lymph nodes. Giant cells and fibroblasts

While secondary TB causes constitutive symptoms such fatigue, weight loss, and fever, primary TB is asymptomatic. along with a productive cough and hemoptysis Lab results: Sputum with acid-fast bacilli, calcified Ghon complex on CXR, and positive PPD test that was validated by culture.

Treatment 
Four-drug TB regimen: ethambutol/streptomycin, pyrazinamide, rifampin, and INH; add two more medications at a time if the strains are resistant to the first two.
PPD test: Indicates post-primary tuberculosis delayed hypersensitivity.