Respiratory Pathology Flashcards
Describe the pathology of asthma?
Type I hypersensitivity reaction (allergens/ cold/ exercise).
-Degranulation of IgE bearing mast cells: histamine initiated bronchoconstriction & mucus production, obstructing air flow. Also eosinophil chemotaxis.
What are the persistent/ irreversible changes of asthma?
- Bronchiolar smooth wall hypertrophy
- Mucus gland hyperplasia
- Respiratory bronchiolitis leading to centrilobar emphysema
What is bronchiectasis?
Permanent dilation of bronchi & bronchioles caused by destruction of the muscle and elastic tissue.
Results from chronic necrotizing infection (like from CF, primary ciliary dyskinesia, bronchial obstruction)
What is COPD?
A combination of emphysema & chronic bronchitis (basically chronic inflammation and infections).
What are the 3 classifications of emphysema?
1) Centrilobar (centiacinar) - coal dust, smoking
2) Panlobar (panacinar) - >80% are antitrypsin deficient, severest in lower lobe bases.
3) Paraseptal (distal acinar) - upper lobe subpleural bullae adjacent to fibrosis.
How can you tell if the COPD is predominantly bronchitis or emphysema?
Bronchitis: 40-45, cough with copious sputum, common infections, prominant vessels & larger heart on xray, blue bloater.
Emphysema: 50-75, late cough, infections rare, small heart & hyperinflated lungs on xray, pink puffer.
Characteristics of interstitial lung disease?
Restrictive lung disease. Increased tissue in alveolar-capillary wall. Inflammation and fibrosis Decreased lung compliance Increased gas diffusion distance
What is acute interstitial lung disease?
Diffuse alveolar damage- exudate & death of type I pneumocytes –> form hyaline membranes lining alveoli, followed by type II pneumocytes.
What is chronic interstitial lung disease?
Dyspnoea increasing for months to years.
Interstitial fibrosis & chronic inflammation with varying radiological & histological patterns.
Common end-stage fibrosed ‘honey-comb lung’
Describe the histological appearance of Idiopathic Pulmonary Fibrosis?
(sub-pleural, lower lobes affected most)
- Interstitial chronic inflammation & variably mature fibrous tissue
- Similar pattern in asbestos
- Bosselated ‘cobblestone’ pleural surface
What is sarcoidosis?
(typically young adult females)
- Non-caseating perilymphatic pulmonary granulomas, then fibrosis. Hilar nodes involved.
- Hypercalcaemia & elevated serum ACE
What are the types of coal worker’s pneumoconiosis?
1) Anthracosis (asymptomatic, milder type- caused by accumulation of carbon)
2) Simple (macular) CWP (nodular aggregations in lungs)
3) Progressive massive fibrosis (if prolonged exposure. Large masses of dense fibrosis in the lungs).
What is silicosis, and what might it lead to?
(silica= sand and stone dust). Kills phagocytosing macrophages. Fibrosis & fibrous silicotic nodules.
- Possible reactivation of TB
- Increased risk of lung carcinoma (prescribed occupational disease in UK)
What is Hypersensitivity Pneumonitis? (aka extrinsic allergic alveolitis)
Type III hypersensitivity reaction, repeated episodes lead to interstitial fibrosis.
- FARMER’S LUNG= actinomycetes in hay
- PIGEON FANCIER’S LUNG= pigeon antigens
What aspects of the GI system are affected by Cystic Fibrosis?
Small Bowel: mucus plugging- meconium ileus
Liver: plugging of bile cannaliculi- cirrhosis
Salivary glands & pancreas: atrophy & fibrosis
What are the 4 major types of primary malignant lung tumours (mostly carcinomas)?
- Squamous cell carcinoma (20-30%)
- Small cell carcinoma (15-20%)
- Adenocarcinoma (30-40%)
- Large cell undifferentiated carcinoma (10-15%)
Aetiology of Lung tumours?
Tobacco smoking Occupational/ Industrial hazards (eg asbestos, arsenic) Radiation (mines- radon) Lung fibrosis Genetic Mutations (EGFR, KRAS, ALK)
What are the electrolytic disturbances of small cell carcinoma?
Hyponatraemia
Hypokalaemia
Hypercalcaemia
What happens in a normal pleural mesothelium?
Single layer of mesothelial cells lines the pleural cavity
Secrete hyaluronic acid rich mucinous pleural fluid (lubricates movement of visceral & parietal pleura)
What are the 2 types of asbestos associated pleural fibrosis?
- Parietal pleural fibrous plaques
- Diffuse pleural fibrous
Characteristics of Parietal pleural fibrous plaques?
- Associated with low level asbestos dust exposure
- Asymptomatic, may be visible of chest radiographs
- Dense poorly cellular collagen
- Not eligible for Industrial Injuries Disablement Benefit