Pathology of lung disease Flashcards
Asthma definition
> irritability of the bronchial tree -temporary reversible narrowing of airways due to inflammatory process occurring within those airways Paroxysmal airway narrowing Reversible -spontaneous -after treatment
Atopic asthma
Triggered by environmental agents e.g. dust
Family history of asthma, hay fever etc.
Type I hypersensitivity reaction
Atopy
Refers to genetic tendency to develop allergic diseases
-such as allergic rhinitis, asthma and atopic dermatitis (eczema)
Typically associated with heightened immune responses to common allergens, especially inhaled allergens and food allergens
Inflammatory reaction (DIAGRAMS)
Caused by mast cells in bronchi
-on surface of these are IgE antibodies formed to some sort of allergen, usually some component of house dust
Upon inhaling allergen, it binds to specific IgE on surface of mast cell and cross links those antibodies
Cross-linking triggers mast cell to de-granulate
-releases large number of inflammatory mediators from mast cell into surrounding cells in bronchus causing acute inflammatory reaction
Treating atopic asthma
Avoidance of the allergen
-e.g. cat/ dog allergy
-not possible for many e.g. pollen
Get rid of inflammatory mast cells from lungs
-inhaled steroid drugs e.g. beclomethasone
Prevent mast cells from granulating when antigen binds to specific IgE antibodies
-disodium cromoglycate
Reverse effects of chemical mediators released when mast cells degranulate
-salbutamol (beta-adrenergic stimulant)
Chronic obstructive airways disease
Emphysema
Chronic bronchitis
Chronic bronchitis definition
Cough and sputum for 3 months in 2 consecutive years
Chronic bronchitis aetiology
Mainly cigarette smoking Air pollution (Clean Air Act 1956)
Chronic bronchitis - clinical features
Middle-aged men
Heavy cigarette smokers
Chronic bronchitis - pathology
Mucous hypersecretion
Chronic inflammation
Squamous metaplasia
Dysplasia (but a feature of the causative agent)
Chronic bronchitis - microbiology (infections/ acute exacerbations on top of chronic bronchitis)
Bacteria -haemophilia influenzae -streptococcus pneumoniae Viruses -respiratory syncytial virus -adenovirus
Definition of emphysema
Anatomical
Enlargement of airspaces distal to the terminal bronchioles with destruction of elastin in walls
-destruction of walls of alveoli can lead to coalescence of spaces to make larger air spaces
< SA for gas exchange
shows darker on radiograph
Lung cancer epidemiology - deaths per year
Males in UK - 52400 deaths/ year
Females in UK - 12600 deaths/ year
-higher incidence in areas with higher social deprivation (smoking, diet?)
Causes of lung cancer
Cigarette smoking 85-90% all cases
Asbestos exposure
Radon exposure (e.g. granite areas in Dark Peaks)
Nickel, chromate etc.
Progression of cells in lung cancer
Ciliated columnar –metaplasia–> squamous –> dysplastic –> invasive cancer
Types of lung cancer
Small cell
Non-small cell
-adeno
-squamous
Prognosis of lung cancer
Only 15-20% of lung cancer are resectable at time of presentation
All the rest are unresectable due either to locally advanced tumours (e.g. gross involvement of subcarinal lymph nodes) or metastasis
Prognosis of lung cancer
- 9% overall 5 year survival rate
- this reflects the low percentage of resectable tumours and poor response to systemic chemotherapuy
In pure economic terms does lung carcinoma have a positive or negative economic balance in Britain?
Probable +ve economic balance
- tax from cigarette purchases for 40 years
- develop disease just before or around retirement age
- treatment relatively cheap
Economics of cigarette smoking
However even in economic terms alone cigarette smoking has an overall debit due to
- COPD
- ischaemic heart disease
Industrial lung disease
Coalworker’s pneumoconiosis
-problem is the silica, not usually the coal dust
Silicosis
Silicates = inorganic minerals abundant in stone and sand
Silicates are toxic to macrophages
Nodules and fibrosis
Asbestos-related diseases
Pleural plaques Pleural fibrosis Mesothelioma Asbestosis Lung carcinoma -body's reaction to asbestos contains iron
Mesothelioma
Almost always associated with asbestos exposure especially crocidolite (Cape blue asbestos)
Malignant tumour of pleura
Long latent period
Incidence will continue to rise into 21st C
Lung carcinoma and asbestos
> in subjects with asbestos exposure
Mutiplicative effect with cigarette smoking
Pink puffers (look up)
Breathe fast
Okay oxygens
Blue bloaters (look up)
Don’t breathe as fast
Look blue
Not enough oxygen going round
Vaping
A bit safer, less carcinogens
-not burning things as much
Lung cancer risks considerably lower
May not lower risk of ischaemic heart disease
