Histo: Lung Pathology Flashcards
What type of epithelium lines the airways?
Ciliated respiratory epithelium
Which types of cells line the alveoli?
Type 1 pneumocytes
What is pulmonary oedema?
Accumulation of fluid in the alverolar spaces either due to leaky capillaries or back pressure from a failing left ventricle
This leads to poor gas exchange
List some causes of pulmonary oedema.
- Left heart failure
- Alveolar injury (e.g. drugs)
- Neurogenic following head trauma
- High altitude
What is the main histological feature of pulmonary oedema?
Intra-alveolar fluid
List some causes of acute respiratory distress syndrome in adults.
- Infection
- Aspiration
- Trauma
- Inhaled irritant gases
- Shock
- DIC
What causes hyaline membrane disease in newborns?
Lack of surfactant (mainly in premature babies)
On a cellular level, what insult results in ARDS?
Acute damage to the endothelium and/or alveolar epithelium
The basic pathology is the same regardless of cause: diffuse alveolar damage
Describe the appearance of the lungs on post-mortem examination in a patient who died from ARDS.
- Plum-coloured
- Heavy (>1kg)
- Airless
Outline the pathophysiology of ARDS.
- Exudative phase - the lungs become congested and leaky
- Hyaline membranes - form when serum protein that is leaked out of vessels end up lining the alveoli
- Organising phase - organisation of the exudates to form granulation tissue sitting within the alveolar spaces
What are the outcomes of ARDS?
- Death
- Superimposed infection
- Resolution (restoration of normal lung function)
- Residual fibrosis (leads to chronic respiratory impairment)
Define asthma.
Chronic inflammatory airway disorder with recurrent reversible episodes of widespread narrowing of the airways
What is the term used to describe a severe attack of asthma where attacks occur one after the other?
Status asthmaticus
List some non-atopic triggers of asthma.
- Air pollution
- Occupational
- Exercise
List some acute changes seen in asthma.
- Bronchospasm
- Oedema
- Hyperaemia
- Inflammation
List some chronic changes seen in asthma.
- Muscular hypertrophy
- Airway narrowing
- Mucus plugging
Describe the main histological features of asthma.
- Lots of eosinophils and mast cells
- Goblet cell hyperplasia
- Mucus plugs within airways
- Thickening of bronchial smooth muscle and dilatation of blood vessels
Define chronic bronchitis.
Chronic cough productive of sputum presents for most days for at least 3 months over 2 consecutive years
List some histological features of chronic bronchitis.
- Diluted airways
- Mucus gland hyperplasia
- Goblet cell hyperplasia
- Mild inflammation
List some complications of chronic bronchitis.
- Recurrent infections
- Chronic respiratory failure
- Pulmonary hypertension and right heart failure (cor pulmonale)
- Increased risk of lung cancer (independent of smoking)
Define emphysema.
Permanent loss of alveolar parenchyma distal to the terminal bronchiole
List some causes of alveolar damage that can lead to emphysema.
- Smoking
- Alpha-1 antitrypsin deficiency
- Rare: cadmium exposure, IVDU, connective tissue disorder
Describe how the pattern of alveolar damage is different with smoking compared to alpha-1 antitrypsin deficiency.
- Smoking - centrilobular damage
- Alpha-1 antritrypsin deficiency - panacinar (throughout the lungs)
List some complications of emphysema.
- Bullae (can rupture to cause pneumothorax)
- Respiratory failue
- Pulmonary hypertension and right heart failure
Define bronchiectasis.
- Permanent abnormal dilatation of the bronchi with inflammation and fibrosis extending into adjacent parenchyma