Pathology of pulmonary infections

Question 1

What is pneumonia?

Answer 1

infection involving the distal airspaces usually with inflammatory exudation (localised oedema). And the fluid filled spaces then lead to consolidation (dull to percuss and crackles heard)

Question 2

What is the difference between influenza and Haemophilus influenzae type b?

Answer 2

Haemophilus influenzae type b is a polysaccharide-encapsulated bacteria that causes a variety of invasive diseases, such as meningitis, epiglottitis, and pneumonia. Influenza is a virus that causes the disease influenza.

Question 3

What organisms can cause pneumonia?

Answer 3

Viruses most commonly - influexna, RSV
Bacterial
Fungi

Question 4

Describe lobar pneumonia?

- and what are some organisms that can cause it

Answer 4

Confluent consolidation involving a complete lung lobe
Most often due to Strep, pneumonia
Also other organisms such as Klebsiella

Question 5

What is the pathology of pneumonia?

Answer 5

Acute inflammation response

• exudation of fibrin-rich fluid
• neutrophil infiltration
• macrophage infiltration
• resolution

Question 6

What are some complications of pneumonia?

Answer 6

Organisation - scarring (fibrous)
Accesses
Bronchiectasis
Empyema

Question 7

Describe bronchopneumonia?

Answer 7

Infection starting in airways and spreading to adjacent alveolar lungs
Usually seen in pre-existing diseases
Results in little patches of inflammation in the lung

Question 8

What are some common diseases that bronchopneumonia occurs in?

Answer 8

COPD
cardiac failure (elderly)
Complication of viral infections such as influenza
Aspiration of gastric contents

Question 9

What are some organisms involved in bronchopneumonia?

Answer 9

Varied

Strep. pneumonia, H.influenza, staph etc

Question 10

What are some complications of bronchopneumonia?

Answer 10

Organisation
Abscess
Bronchiectasis
Empyema

Question 11

Roughly describe lung abscess?

Answer 11

Localised collection of pus
chronic malaise and fever
usually in aspiration

Question 12

Describe bronchiectasis?

Answer 12

Form of chronic pus formation in lung.
Abnormal fixed dilatation of the bronchi
Usually due to fibrosis scarring following infection (pneumonia, TB, CF)
Dilated airways accumulate purulent secretions which can accumulate and turn into pus - thus coughing up sputum

Bronchiectasis is a long-term condition where the airways of the lungs become abnormally widened, leading to a build-up of excess mucus that can make the lungs more vulnerable to infection.

Question 13

Describe TB roughly?

Answer 13

Infection due to mycobacterial
Chronic infection that you can get anywhere in the body
Characterised by delayed type 4 hypersensitivity reaction (granulomas with necrosis)

Question 14

What organisms cause TB?

Answer 14

M. bovis

M. TB

Question 15

Describe what the T cell response is in both terms of immunity and hypersensitivity?

Answer 15

Immunity - T cell response to organism enhances macrophage ability to kill the mycobacteria

Hypersensitivity - T cell response causes granulomatous inflammation, tissue necrosis and scarring

Question 16

Describe primary TB?

Answer 16

!st exposure to the pathogen
The inhaled organism is phagocytksed by macrophages and carried to the hilar lymph nodes. Immune activation ( few weeks) leads to a granulmonatous response in nodes (and also in lung) usually with killing of organisms.

Question 17

Describe secondary TB?

Answer 17

Reinfection and reactivation of disease in a person with some immunity
Disease tends initially to remain localised often in the apices of the lung
can progress to spread by airways and/or bloodstream

Question 18

Describe what tissue changes you see in primary TB?

Answer 18

Ghon focus in periphery of mid zone of lung

Large hilar notes

Question 19

Describe what tissue changes you see in secondary TB?

Answer 19

Fibrosisng and cavitating apical lesion

Question 20

Why might disease reactivate?

Answer 20

Decrease T cell function

• age
• conincident disease (HIV)
• immunosuppressive therapy (steroids, cancer treatment etc)