Lung pathology lecture Flashcards
What is bronchial asthma?
Episodic and reversible airway constriction
What are the two main types of asthma?
extrinsic and intrinsic
What is the pathogenesis of extrinsic asthma?
It is more common in children and due to exposure to allergens
First time the allergen is encountered this stimulates T cells to produce antibody production
Second time it is encountered antibodies react to allergen which causes mast cell degranulation and bronchoconstriction
What histological changes occur in the bronchi and bronchioles in asthma?
Get thickening of the basement membrane and hypertrophy of smooth muscle cells in the bronchi.
Get mucus plugs in the bronchioles
What are the clinical findings in asthma?
Episodic expiratory wheeze
Nocturnal cough
Diagnosis is generally made through PEFR which is 20% variability generally lowest in morning and is reversible with treatment
How is asthma treated?
Treated with beta 2 agonists e.g. salbutamol
In more severe disease corticosteroids e.g. beclometasone, are used and leukotriene inhibitors
What is the pathology behind intrinsic asthma?
This is non immune
Can be caused by viral respiratory infections, air pollutants or drug sensitivity
What is COPD?
Progressive largerly irrevversible obstruction to airflow out of the lungs
Majority of patients with COPD have both emphysema and chronic bronchitis
What is emphysema?
Permanent enlargement of part or all of the respiratory unit (respiratory bronchioles, alveolar ducts and alveoli
What are the main causes of emphysema?
Smoking
Alpha 1 antitrypsin deficiency (AAT)
What is the pathogenesis of emphysema?
There is increased compliance and decreased elasticity
Smoking is chemotaxic for neutrophils and macrophages
Destruction of elastic tissue means small airways collapse
These collapsing typically terminal bronchioles prevent air leaving on expiration causing dilation and decreased elasticity of the alveoli.
What are the two types of emphysema and what are their differences?
Centrilobular emphysema is most common and it involves dilation of the respiratory bronchioles
It is most severe in the upper lobes
Panacinar effects the whole lobule and it all becomes distended, mainly affects the lower lobes
What are the clinical findings in emphysema?
Dyspnea is severe and occurs early in the disease
Hypoxemia occurs later hence ‘pink puffers’
Breath sounds are diminished from hyperinflation
What treatment options are there for COPD?
Stopping smoking most important Pulmonary rehab program oxygen with nasal prongs to maintain 88-92% Bronchodilators Anticholinergics
What is chronic bronchitis?
Productive cough for at least 3 months for 2 consecutive years
What are the two main causes of chronic bronchitis?
Smoking
Cystic fibrosis
What is the pathogenesis behind chronic bronchitis?
Hypersecretion of mucus in bronchus and subdivisions
Irreversible fibrosis may occur in the chronically inflamed bronchi
Lose ciliated epithelium and often squamous metaplasia
What are the clinical findings in chronic bronchitis?
Productive cough Dyspnea late in the disease Hypoxemia and resp acidosis occur early hence 'blue bloater' Expiratory wheeze Cor pulmonale is commonly present
What is bronchiectasis?
Permanent dilation of the bronchi and bronchioles causing repeated episodes of airway infection and inflammation.
What are the main causes of bronchiectasis?
Cycstic fibrosis is most common cause
Infections e.g. TB and haemophilus Influenzae
Obstruction in a primary bronchus e.g. carcinoma causes bronchiectasis distal to this
Primary ciliary dyskinesea
What are the gross findings in bronchiectasis?
Most commonly occurs in lower lobes
Dilated bronchi and bronchioles filled with pus
What are the clinical findings in bronchiectasis?
Cough productive with lots of sputum
Haemoptysis
Clubbing
Cor pulmonale
What are the imaging findings for bronchiectasis?
On chest X ray may see tram line signs
On CT there is signet ring sign
What is the pathogenesis of interstitial fibrosis?
The earliest signs are an alveolitis
The fibrosis causes decreased lung compliance and decreased expansion of the lung during inspiration
The elasticity of the lung increases so recoil on expiration is increased
What is a pneumoconioses?
A group of lung diseases in which inhalation of mineral dust leads to interstitual fibrrosis
Which particles that can be inhaled are fibrinogenic and which are not?
Coal dust is the least fibrinogenic
Silica and asbestos are very fibrinogenic
What is the cause of coal workers pneumoconioses and how do they appear on imaging?
Caused by inhaling coal dust, usually asymptomatic
Appears as fibrotic opacities on imaging
What is the pathogenesis of silicosis and what are the imaging findings?
It is caused by breathing in quartz dust (crystalline silicon dioxide)
This is highly fibrinogenic and activates macrophages causing fibrosis
It is mainly deposited in the upper lungs
This causes a ground glass appearance on cxr acutely
Chronic exposure causes nodular opacities caused by concentric layers of collagen
What can asbestosis lead to?
Lung cancer, interstitial fibrosis and mesothelioma
What is the definition of sarcoidosis?
A multisystem noninfectious granulomatous disease that produces chronic interstitial fibrosis
What is the pathogenesis of sarcoidosis and some of the clinical findings?
It is due to a disorder of immune regulation in which cd4 t cells interact with unknown airborne antigens e.g. mold and release cytokines to cause granulomas
The clinical findings include:
-dyspnea is most common symptom
-skin lesions including nodular granuloma lesions, rash on the nose and cheeks, erythema nodosum (nodules on lower extremities)
-uveitis
-liver lesions - granulomatous hepatitis
-granulomas in bone marrow and spleen
What would a chest radiograph of sarcoidosis show?
Enlarged hilar and mediastinal nodes (potato nodes)
Reticulo-nodular densities in lung parenchyma
What are the treatments for sarcoidosis?
Majority have spontaneous remission in 3 years and do not require treatment
Corticosteroids e.g. prednisolone
Tumour necrosis factor inhibitors (tnf) used rarely e.g. infliximab
What is the pathogenesis for interstitial pulmonary fibrosis?
Repeated cycles of alveolitis trigfered by an unknown agent cause cytokine release which causes an interstitial pulmonary fibrosis
What are the clinical findings in idiopathic pulmonary fibrosis?
Fever
Dyspnea with exertion
Chronic non productive cough
Late inspirtory crackles
What is the treatment available for idiopathic pulmonary fibrosis?
No real treatment options available
Steroids advised against unless you think it may be some other cause
Monoclonal antibody therapies beginning to become available
What are some systemic causes of interstitial lung disease?
Systemic sclerosis
Systemic lupus erythematosus
Rheumatoid arthritis
What is hypersensitivity pneumonitis? What is its pathogenesis?
It is an extrinsic allergic allveolitis associated with exposure to a known inhaled antigen
It does not involve IgE antibodies (type 1 hypersensitivity)
What are the main causes of extrinsic allergic alveolitis?
Bird fanciers lung (droppings)
Farmers lung from mouldy hay
What are the main treatments for extrinsic allergic alveolitis?
Remove allergens and treat with steroids