What is secondary tuberculosis?
Secondary Tuberculosis (Reactivation or Post-primary TB) Secondary tuberculosis is the form of TB that occurs in a person who has previously been infected with Mycobacterium tuberculosis . It may result from reactivation of latent TB or reinfection with a new strain, usually in the lungs . Causes Reactivation of dormant bacilli from a previous primary infection (common) Reinfection from external sources (less common, but possible) Occurs when: Immunity weakens (e.g., HIV, malnutrition, old age, diabetes, immunosuppressive therapy) Common Sites Apex of the lungs (upper lobes) Higher oxygen tension here favors mycobacterial growth Pathological Features Feature Details Lesion type Caseating granulomas, cavitary lesions Cavity formation Due to caseous necrosis and tissue destruction Fibrosis and scarring Seen in chronic cases Possible spread Local (to other lung areas) or systemic (via blood or lymph) Clinical Features Symp...