Interstitial Lung Diseases Flashcards
What is an interstitial lung disease?
Any disease process affecting lung interstitium (ie alveoli, terminal bronchi).
Are interstitial lung diseases restrictive or obstructive?
restrictive
What is sarcoidosis?
Granulomatous (type 4 hypersensitivity) disease of unknown cause
(non ceaseating granuloma)
What are the signs of acute sarcoidosis?
erythema nodosum bilateral hilar lymphadenopathy arthritis uveitis, parotitis fever.
What are the signs of chronic sarcoidosis?
lung infiltrates (alveolitis) skin infiltrations peripheral lymphadenopathy hypercalcaemia Other organs: renal, myocardial, neurological, hepatitis, splenomegaly
What investigations should be carried out for sarcoidosis?
Chest X-ray (BHL)
CT scan of lungs (peripheral nodular infiltrate)
Tissue biopsy (eg transbronchial, skin, lymph node) non-caseating granuloma.
Pulmonary function: Restrictive defect due to lung infiltrates.
Blood test:
- Angiotensin Converting Enzyme (ACE) levels as activity marker (NOT diagnostic test).
- raised calcium
- increased inflammatory markers
What is the treatment for acute sarcoidosis?
self-limiting condition - usually no treatment
Steroids if vital organ affected (eg impaired lung function, heart, eyes, brain, kidneys)
What is the treatment for chronic sarcoidosis?
oral steroids usually needed
Immunosuppression (eg azathioprine, methotrexate)
What is extrinsic allergic alveolitis?
Type 2 hypersensitivity in reaction to antigen
What are examples of extrinsic allergic alveolitis?
farmer’s lung, bird fancier’s lung
What are the symptoms and signs of acute extrinsic allergic alveolitis?
cough, breathless, fever, myalgia –
Classically symptoms occur several hours after acute exposure (flu-like illness)
Signs: +/- pyrexia, crackles (no wheeze!), hypoxia
CxR: widespread pulmonary infiltrates
How can acute extrinsic allergic alveolitis be treated?
oxygen, steroid and antigen avoidance
What are signs and symptoms of chronic extrinsic allergic alveolitis?
progressive breathlessness and cough
Signs: may be crackles, clubbing is unusual
CxR pulmonary fibrosis - most commonly in the upper zones
PFTs: restrictive defect (low FEV1 & FVC, high or normal ratio, low gas transfer - TLCO)
How is chronic extrinsic allergic alveolitis diagnosed?
history of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if in doubt
How is chronic extrinsic allergic alveolitis treated?
remove antigen exposure, oral steroids if breathless or low gas transfer
What is the most common interstitial lung disease?
IDIOPATHIC PULMONARY FIBROSIS
What are the clinical features of idiopathic pulmonary fibrosis?
Clinical presentation: progressive breathlessness (several years), dry cough
OE: clubbing, bilateral fine inspiratory crackles
Ix: restrictive defect on PFT’s - reduced FEV1 and FVC with normal or raised FEV1/FVC ratio, reduced lung volumes, low gas transfer
CxR - bilateral infiltrates;
CT scan - reticulonodular fibrotic change, worse at the lung bases. The presence of “ground-glass” suggests reversible alveolitis; fibrosis is irreversible.
lung biopsy – not necessary if CT scan is diagnositic
What is the pathology of idiopathic pulmonary fibrosis?
chronic inflammatory infiltrate (neutrophils and fibrosis in alveolar walls ± intra-alveolar macrophages
What is the treatment for idiopathic pulmonary fibrosis?
oral steroids ± immunosuppressive drugs
What does silicosis result from exposure to?
quartz
