Pathology of Lung Infection

Question 1

What are the two patterns of acute bacterial pneumonia in the lung?

Answer 1

Acute bronchopneumonia and acute lobar pneumonia

Question 2

What is acute bronchopneumonia?

Answer 2

• Tends to be low virulence organisms - Multiple lobes involved - Produces multiple discrete inflammations - Inflammation usually starts in the terminal bronchiole

Question 3

What is lobar pneumonia?

Answer 3

• Inflammatory oedema spreads throughout the entire lobe - Often high virulence organisms (80% with strep. pneumoniae) - Bronchial breath sounds - More likely to cause pleurisy - Consolidation

Question 4

What is acute bronchopneumonia?

Answer 4

• Tends to be low virulence organisms - Multiple lobes involved - Produces multiple discrete inflammations - Inflammation usually starts in the terminal bronchiole - Consolidation

Question 5

What is a lung abscess?

Answer 5

Cavity containing pus Causes: - aspiration - obstruction of the bronchial tree - certain types of bacterial infections - strep. pyogenes, staph aureus, klebsiella pneumoniae - acute bronchopneumonia in a debilitated host

Question 6

What are the differences between viral and bacterial pneumonia?

Answer 6

Viral - acute inflamm with lymphocytes rather than neutrophils - no consolidation - can cause bronchiolitis and inflammation of the alveolar septa - cytopathic - kill epithelial cells, predispose to secondary bacterial infection

Question 7

What is acute bronchopneumonia?

Answer 7

• Tends to be low virulence organisms - Multiple lobes involved - Produces multiple discrete inflammations - Inflammation usually starts in the terminal bronchiole - Consolidation

Question 8

What is bronchiectasis?

Answer 8

Permanent and irreversible dilation of the bronchi

• weakening of the bronchial wall by inflammation
• scar tissue deposition
• dilation
• pooling of secretions

Question 9

What are the complications of bronchiectasis?

Answer 9

• Copious offensive sputum production
• recurrent bacterial pneumonia and abscesses
• rupture of vessles in bronchial walls leads to haemoptysis
• pulmonary fibrosis leading to RV failure (cor pulmonale)
• cerebral abscesses
• amyloidosis

Question 10

What is Pulmonary Tuberculosis?

Answer 10

Chronic bacterial infection (Mycobacterium Tuberculosis) that often infects the lungs

• characterised by granulomatous inflammation and caseous necrosis (what destroys the lung parenchyma)

Question 11

What is primary TB?

Answer 11

Pattern of TB which occurs in previously unexposed indiviuals

• peripheral area of granulomatous inflammation and caseation = Ghon focus
• bacteria drain to hilar lymph nodes which also caseate
• Ghon focus + invovled node = Ghon complex
• in most patients, immune response controls the infection and the Ghon complex heals by fibrosis

Question 12

What is secondary TB?

Answer 12

Occurs in previousy infected indivudal - immune system sensitised

• apical areas of the upper lobes
• tubercles and caseation
• cavitation occurs - caseous necrosis erodes into the wall and discharges throuh the bronchial tree
• healing by fibrosis (immune response or treatment)
• dystrophic calcification

Question 13

What are some complications of secondary TB?

Answer 13

• progressive spread of caseation into surrounding lung
• erosion of blood vessels (haemoptysis)
• spread of infection via airways
• pleural inflammation and fibrous
• lung scarring

Question 14

What is miliary TB?

Answer 14

Numerous small tubercles/granulomas widely scattered throughout the lung parenchyma/other organs

• disseminated tuberculosis, very high mortality
• more common in patients with compromised immune system