TB Flashcards
What is pulmonary tuberculosis?
Chronic granulomatous pneumonia due to infection with MTB
What kind of necrosis is seen within granulomatous tubercles in TB?
Caseous
What is a granuloma?
Central caseous necrosis surrounded by an aggregate of epithelioid macrophages, lymphocytes and multinucleated giant cells
What is a Ghon focus?
Peripheral area of granulomatous inflammation and caseation in the lung, seen in primary TB
What is a Ghon complex?
Ghon focus + caseated hilar LN draining bacteria
How is primary TB resolved in most patients?
Immune response controls infection
Ghon complex heals by fibrosis, often with some calcification
What is secondary TB? What are the complications?
Reactivation of dormant infection or reinfection
How are granulomas formed?
Via a type IV hypersensitivity reaction
What lung changes occur with secondary TB?
Lobar pneumonia of apical areas of upper lobes
Tubercles and caseation
Dystrophic calcification and fibrosis in attempt to localise infection
What are the possible complications of secondary TB?
Progressive spread of caseation into surrounding lung
Erosion of blood vessels can cause haemoptysis
Erosion into bronchial tree can cause cavitation and spread
Pleural inflammation and fibrosis
Lung scarring
What are the classical symptoms of TB?
Weight loss Malaise Fevers, rigors Night sweats Haemoptysis Dyspnoea Chronic cough
Describe the structure and defining characteristics of Mycobacterium tuberculosis
Aerobic rods
Cell wall composed of mycolic acid (acid-fast; ZN stain used to visualise)
What is miliary TB? Does it occur in primary or secondary TB?
Form of progressive tuberculosis caused by dissemination of bacteria via the bloodstream
Can occur in primary and secondary TB
What organs are involved in miliary TB?
Lung
Multiple other organs, e.g. liver, spleen, bone marrow, brain
What is the defining pathological feature seen in miliary TB?
Numerous small (2-3mm) granulomas in lungs or other organs
