Pathology and Histology Flashcards
What is pneumonia?
Infection involving the distal aspects of the respiratory tree including localised oedema
What is lobar pneumonia?
Pneumonia involving a complete lung lobe
What are the different types of pneumonia (based on where infection was acquired)?
- Community acquired
- Hospital aquired
- Aspiration
During a classical acute inflammatory response what are the main stages in a pneumonia?
- Exudation - emission of fibrin-rich fluid through pores or wounds
- Infiltration by neutrophils
- Infiltration by macrophages
- Resolution
Why is pneumonia potentially able to cause long term damage?
Organisation of tissues during healing can cause fibrous scarring
Abcesses can form
Bronchiestasis can occur - abnormal dilation of bronchi
Empyema - collection of pus in body cavity most commonly the pleura
What is bronchopneumonia?
This is when infection causing pneumonia starts in the airways and proceeds to infect the alveolar lung
This is common when the patient has pre-existing disease
Which pathogens can cause bronchpneumonia?
Strep. pneumoniae, Haemophilius influenza, S. aureus, anaerobes and coliforms
What is an abscess?
A local collection of pus
Can cause chronic malaise and fever
Caused by aspiration of pathogens
What is bronchiestasis?
Fixed dilatation of bronchi
This is due to fibrous scarring after infection, or chronic obstruction
Which pathogen is most likely to cause Tb?
Mycobacterium tuberculosis
(M.bovis can also cause Tb)
What is a key sign of Tb?
Granuloma formation
Caseating ācheesyā necrosis
This is due to a delayed hypersensitivity (type IV) reaction
What is primary Tb?
The first exposure to Tb
The pathogen is phagocytosed and taken to hilar lymph nodes which provokes an immune reaction leading to a granulomatous response
What is secondary Tb?
This is a secondary encounter with Tb and involves reinfection and reactivation
A degree of immunity will be present
Generally the disease will still remain localised to the lung apices
Describe the tissue changes in primary Tb
Small focuses (Ghon focuses) occur which are small lesions caused by the mycobacterium
Large hilar nodes will develop due to the granulomas forming
Describe the tissue changes in secondary Tb
Fibrosis and cavitating of apical lesions will occur
This worsens the damage already present
Why may reactivation with Tb occur?
Decrease in T cell function due to:
- Age
- Immunosuppression due to disease (HIV)
- Immunosuppression due to therapy - steroids, chemo
How may a patient be diagnosed with Tb?
- History
- Broncho-alveolar lavage - bronchoscope is passed into the lungs and squirts fluid into the lungs which is subsequently collected for study
- Biopsy
What is the pulmonary interstitium
This is where gas exchange occurs
Contains alveolar type I and II cells as well as thin connective tissue high in elastin
How does ILD commence?
Any form of injury that leads to alveolitis - inflammation of the alveoli
What are the two umbrella causes for ILD?
- Environmental - minerals (asbestos), drugs, radiation
- Idiopathic
How can ILD be diagnosed?
- Transbronchial biopsy
- Thoracoscopic biopsy - more invasive - thoracoscope enters through an incision between ribs allowing for visual inspection of the lungs
What are some forms of ILD?
- Fibrosing alveolitis
- Sarcoidosis
- Extrinsic allergic alveolitis (hypersensitivity pneumonitis)
- Pneumoconiosis - occupational lung disease
- Connective tissue disease
What is fibrosing alveolitis?
A type of idiopathic pulmonary fibrosis
Inflammation is usually associated with the condition
Finger clubbing is a common symptom
What is the pathology of fibrosing alveolitis?
A sub-pleural and basal fibrosis occurs due to inflammation
In the terminal stages the lung structure becomes composed of large dilated spaces surrounded by fibrous walls - this is honeycombing
These thick walla and dilated spaces hinder gas exchange
What is extrinsic allergic alveolitis?
Chronic inflammation due to a type III and type IV hypersensitivity reaction
Airways become small and granulomas can be formed from collections of activated macrophages
What are some causes/forms of extrinsic allergic alveolitis?
- Thermophilic bacteria - Farmerās lung
- Avian proteins - Pigeon fancierās lung
- Fungi - Malt workerās lung
How can extrinsic allergic alveolitis diagnosed?
The presence of antibodies called precipitins can be detectable in the blood serum which indicate hypersensitivity reactions
Biopsies can be utilised to diagnose more difficult conditions
What is sarcidosis?
A multisystem granulomatous disorder commonly affecting the pulmonary system
In what ways can sarcoidosis manifest itself?
- Uveitis - inflammation of iris
- Erythema nodosum - inflammation of fat cells under the skin causing red patches
- Lympthadenopathy
- Hypercalcaemia
What effects can connective tissue diseases have on the pulmonary system?
- Interstitial fibrosis
- Pleural effusions
- Rheumatoid nodules - local swelling or lumps most often associated with rheumatoid arthritis
What is pneumoconiosis?
An umbrella term for ādust diseasesā
Characterised by inalation of ādustā, inflammation and fibrosis
What are three types of pneumoconiosis?
- Asbestosis
- Coal workerās lung
- Silicosis