Pathology of Restrictive Lung Diseases Flashcards
What happens to lung compliance in restrictive disease and why?
Reduced compliance
- Stiff lungs due to thicker interstitium
- Inflammatory process eventually leading to collagen being laid down which doesn’t stretch
What happens to FEV1 and FVC in restrictive lung disease?
Low FEV1 and FVC
FEV1/FVC normal or increased ratio
Reduced gas transfer
Ventilation/perfusions imbalance
What is the presentation of diffuse lung disease?
Discovery of abnormal CXR or CT scan
Dyspnoea
- SOB of exertion
- Progressing to SOB at rest
Respiratory failure
Heart failure
What are the main features of a CXR of interstitial lung disease?
Compressed lungs
Fluffy heart border
What is the pathology of diffuse alveolar damage (DAD or ARDS)
- Acute inflammatory response involving lots of tissue damage
- Early vascular phase producing lots of fluid (exudate stage) - may result in haemorrhage
- Cellular and proliferation - chronic inflammatory process
- Disease evolves at different stages in different parts of the lung
What is DADs associated with?
Major trauma
Chemical injury/toxic inhalation
Circulatory shock
Drugs
Infection including viruses
Autoimmune disease
Radiation
Idiopathic
What is the histology of DADs like?
Protein rich
Fibrin
Hyaline membranes
Denuded basement membranes
Attempt to remodel lung
Scarring of the lung
What is a hyaline membrane?
Layer of proteinates material becoming layered on alveolar walls.
What occurs when the lung attempts to remodel?
Epithelial proliferation
Fibroblast proliferation
What is sarcoidosis?
A multisystem granulomatous disorder of unknow aetiology
What is the prognosis of sarcoidosis?
Relatively good
- There is only a small possibility it will progress to end stage fibrosis
Stage 1 usually resolves after 2 years
Stages 2&3 may resolve, persist or progress
What is the histopathology of sarcoidosis?
Epithelioid and giant cell granulomas
Necrosis/cessation very unusual
Little lymphoid infiltrate
Variable associated fibrosis
What is the incidence of sarcoidosis worldwide and what does this suggest?
3-4/100,000 in UK
20/100,000 in African-Americans
Low in equatorial regions
*A disease of temperate climate
What organs can be involved in sarcoidosis and what is the likelihood of involvement?
Lymph node= almost 100%
Lungs >90%
Spleen 75%
Liver 70%
Skin, eyes, skeletal muscle 50%
Bone marrow 20%
Salivary glands up to 50%
How does sarcoidosis present?
Acute arthralgia
Erythema nodosum
Bilateral hilar lymphadenopathy
Incidental abnormal CXR or CT scan - if asymptomatic
SOB
Cough
What is the treatment for sarcoidosis?
Corticosteroids
How do you diagnose sarcoidosis?
Clinical findings
Imaging findings
Serum Ca++ and ACE
Biopsy
What is the interstitium?
The connective tissue potential space around the airways and vessels and the space between the basement membranes of the alveolar walls.
What does the interstitium look like in normal cells?
Very thin (see sheet) to allow for gas exchange
What happens in interstitial disease?
Interstitium is thickened by interstitial infiltrate making gas exchange harder/impossible
What is hypersensitivity pneumonitis?
Patient is exposed to particular antigen to which they are sensitive to leading to hypersensitive reaction.
How does a hypersensitive reaction come about?
Inhaled antigen that patient is exposed to
Coupled with immunogenetic make up
What are some common antigens that cause hypersensitivity pneumonitis?
Thermophilic actinomycetes (in mouldy hay)
Bird/animal proteins
Fungi
Chemicals
What is the acute presentation of hypersensitivity pneumonitis? (8)
Fever
Dry cough
Myalgia
Chills 4-9 hours after Ag exposure
Crackles
Tachypnoea
Wheeze
Precipitation antibody
What is the chronic presentation of hypersensitivity pneumonitis? (7)
Insidious
Malaise
SOB
Cough
Low grade illness
Crackles
Wheeze
What mediates the immune complex of hypersensitivity pneumonitis?
Combined Type 3 and 4 hypersensitivity reactions
What is the histopathology of hypersensitivity pneumonitis?
Soft centriacinar epithelioid granulomata
Interstitial pneumonitis
Foamy histiocytes
Bronchiolitis obliterans
What lung zones does hypersensitivity pneumonitis effect most?
Upper zones
(as this is where inhaled bacteria/antigen usually end up)
What are the response from type 3 and 4 hypersensitivity reactions?
Type 3 = lymphocytes
Type 4 = granuloma
How can idiopathic pulmonary fibrosis (IPF) be diagnosed?
Clinically - may be associated with radiological features
What is the pathology of IPF?
Usual interstitial pneumonitis
What is the aetiology of IPF? (5)
Connective tissue diseases
Drugs
Asbestos
Viruses
Idiopathic
What are the treatment options for IPF?
No treatment
One way journey to resp failure - probability of developing end stage fibrosis is very high
What is the histology of IPF? (5)
Patchy interstitial chronic inflammation
Type 2 pneumocyte hyperplasia
Smooth muscle and vascular proliferation
Evidence of old/recent injury
Proliferating fibroblastic foci
What are the signs of old/recent injury and what does this show?
Temporal heterogeneity
Spatial heterogeneity
**disease is evolving: new - moderate - old - very old all seen within the same area
What are the clinical signs of IPF? (5)
Dyspnoea
Cough
Basal crackles
Cyanosis
Clubbing
What is the prognosis of IPF?
Not good - usually ends with end stage fibrosis
Progressive disease = most dead in 5 years
What does a CXR show for IPF patients?
Basal/posterior
Diffuse infiltrates
Cysts
‘Ground glass@
What are the investigation results for IPF?
Restrictive pulmonary function tests
Reduced gas transfer
What is honeycombing of the lung?
End stage fibrotic areas of lung as a result of many different fibrosing conditions
What does an end stage lung look like?
Shrunken - fibrotic so cant expand/stretch
Non functioning
