Fibrotic lung disease (RESP) Flashcards
Define interstitial lung disease.
Group of disorders characterised by inflammation and progressive scarring (fibrosis) of the lungs
What are some causes of interstitial lung disease? (5)
- idiopathic pulmonary fibrosis (IPF)
- hypersensitivity pneumonitis (extrinsic allergic alveolitis) - people with chronic exposure to bird droppings
- pneumoconiosis (asbestosis) - people in coal mining industry
- substance-induced (amiodarone, nitrofurantoin, methotrexate, bleomycin - chemo drug)
- secondary to underlying disease e.g. connective tissue disorders, sarcoidosis, vasculitis
Who can hypersensitivity pneumonitis (interstitial lung disease) occur in?
People with chronic exposure to bird droppings
What is the pathophysiology of hypersensitivity pneumonitis (interstitial lung disease)?
Type 3 hypersensitivity-induced lung damage due to variety of inhaled organic particles
Who does pneumoconiosis AKA asbestosis (interstitial lung disease) happen in?
People in the coal mining industry
How does pneumoconiosis (interstitial lung disease) present?
Asymptomatic but may lead to progressive massive upper zone fibrosis which is symptomatic
What underlying diseases can cause interstitial lung disease? (3)
- connective tissue disorders
- sarcoidosis
- vasculitis
What is the most common type of interstitial lung disease?
Idiopathic pulmonary fibrosis - diagnosed when there is no other identifiable cause, rare form of fibrotic lung disease with no known aetiology
Who does idiopathic pulmonary fibrosis tend to affect?
Men 50-70 years old
What is idiopathic pulmonary fibrosis characterised by?
Scar tissue formation within lungs, dyspnoea, significantly shortened lifespan after diagnosis
List the causes of upper zone fibrosis. (6)
CHARTS
- Coal workers pneumoconiosis
- Histiocytosis/Hypersensitivity pneumonitis
- Ankylosing spondylitis
- Radiation
- Tuberculosis
- Sarcoidosis/silicosis
List the causes of lower zone fibrosis. (4)
DIAL
- Drugs - amiodarone, nitrofurantoin, methotrexate, chemo (bleomycin)
- Idiopathic pulmonary fibrosis
- Asbestosis
- Lupus (and other CTDs except ankylosing spondylitis)
Describe the aetiology of interstitial lung disease.
- occurs in genetically predisposed individuals
- recurrent injury to alveolar epithelial cells –> secretion of cytokines and growth factors by pneumocytes especially TGFb1
- usually there is interstitial tissue in between alveoli and capillaries containing fibroblasts and macrophages
- cytokines cause fibroblast activation, recruitment, proliferation, differentiation into myofibroblasts and increased collagen synthesis and deposition –> thickened interstitial layer –> problems with ventilation and oxygenation + stiffer alveoli
Is interstitial lung disease obstructive or restrictive?
Restrictive - restricted lung expansion due to fibrosis of interstitium
What is interstitial lung disease characterised by?
Honeycombing: loss of alveoli –> fluid-filled cysts surrounded by thick wall