Respiratory - Interstitial Lung Disease Flashcards
What is interstitial lung disease?
A group of conditions that affect the lung parenchyma, causing inflammation and fibrosis.
Conditions that are classified as interstitial lung disease include:
- sarcoidosis
- hypersensitivity pneumonitis
- usual interstitial pneumonia
How is interstitial lung disease diagnosed?
High resolution CT of the thorax, showing ground glass appearance.
When diagnosis is unclear, lung biopsy can be used to confirm the diagnosis via histology.
What pattern of lung disease will ILD show on lung function tests?
Restrictive lung disease (FEV1/FVC >0.8)
How is ILD managed?
Poor prognosis and limited management as the damage is irreversible - treatment is supportive:
- home oxygen if hypoxic at rest
- smoking cessation
- physiotherapy and pulmonary rehabilitation
- pneumococcal and flu vaccine
- advances care / palliative care planning
- lung transplant
What is idiopathic pulmonary fibrosis?
Progressive pulmonary fibrosis with no clear cause, presenting with insidious onset of SOB and dry cough.
Examination can show bibasal fine inspiratory crackles and finger clubbing.
List some drugs that can induce pulmonary fibrosis.
- amiodarone
- cyclophosphamide
- methotrexate
- nitrofurantoin
Secondary to which other conditions can pulmonary fibrosis occur?
- alpha-1 antitrypsin deficiency
- rheumatoid arthritis
- systemic lupus erythematosus (SLE)
- systemic sclerosis
What is usual interstitial pneumonia (UIP)?
Commonest type of pulmonary fibrosis, usually of idiopathic aetiology.
Classic findings include:
- bibasal inspiratory crackles
- clubbing
- reduced chest expansion
- pulmonary hypertension
Outline the pathophysiology of hypersensitivity pneumonitis (AKA extrinsic allergic alveolitis).
Type 3 hypersensitivity reaction to environmental allergens causes parenchymal inflammation and destruction.
Examples of specific causes:
- bird-fanciers lung is a reaction to bird droppings
- farmers lung is a reaction to mouldy spores in hay
- mushroom worker’s lung is a reaction to specific mushroom antigens
- malt workers lung is a reaction to mould on barley
What is asbestosis?
Lung fibrosis related to the inhalation of asbestos, usually occurring decades after original exposure.
Asbestos is fibrogenic and oncogenic, so can cause several complications:
- lung fibrosis
- pleural thickening
- adenocarcinoma
- mesothelioma
What is sarcoidosis?
A granulomatous multi-system inflammatory condition, associated with chest symptoms and extra-pulmonary manifestations.
Presentation of sarcoidosis.
Two spikes in incidence - young adulthood and around age 60. Women and BAME more commonly affected.
- cough
- fever
- fatigue
- weight loss
- erythema nodosum
What are the effects of sarcoidosis on the lungs (~90%)?
- mediastinal lymphadenopathy
- pulmonary fibrosis
- pulmonary nodules
What are the effects of sarcoidosis on the liver (~20%)?
- liver nodules
- cirrhosis
- cholestasis
What are the effects of sarcoidosis on the eyes (~20%)?
- uveitis
- conjunctivitis
- optic neuritis
What are the effects of sarcoidosis on the skin (~15%)?
- erythema nodosum
- lupus pernio
What are the effects of sarcoidosis on the heart (~5%)?
- bundle branch block
- heart block
- myocardial muscle involvement
What are the effects of sarcoidosis on the kidneys (~5%)?
- kidney stones (hypercalcaemia)
- nephrocalcinosis
- interstitial nephritis
What are the effects of sarcoidosis on the central nervous system (~5%)?
- nodules
- diabetes insipidus (pituitary involvement)
- encephalopathy
What are the effects of sarcoidosis on the peripheral nervous system (~5%)?
- facial nerve palsy
What are the effects of sarcoidosis on the bones (~2%)?
- arthralgia
- arthritis
- myopathy
What is Lofgren’s syndrome?
A specific presentation of sarcoidosis:
- erythema nodosum
- bilateral hilar lymphadenopathy
- polyarthralgia (pain in multiple joints)
Give some differential diagnoses for sarcoidosis.
- tuberculosis
- lymphoma
- hypersensitivity pneumonitis
- HIV
What blood test findings would be consistent with a diagnosis of sarcoidosis?
- raised serum ACE
- hypercalcaemia
- raised CRP
What imaging findings would be consistent with a diagnosis of sarcoidosis?
CXR - hilar lymphadenopathy
HRCT - hilar lymphadenopathy; pulmonary nodules
MRI - CNS involvement
PET scan shows active inflammation
What is the GOLD STANDARD for sarcoidosis diagnosis?
Bronchoscopy with ultrasound guided biopsy of mediastinal lymph nodes.
Histology shows characteristic non-caseating granulomas, with epithelioid cells.
How is sarcoidosis treated?
No treatment is patient has no or mild symptoms, as the condition will often resolve spontaneously.
Oral steroids are first line where treatment is required; patients should be given bisphosphonates to protect against osteoporosis while on long term steroids.
What is the prognosis of sarcoidosis?
Spontaneously resolves within 6 months in approx. 60% of patients.
Can progress with pulmonary fibrosis and pulmonary hypertension.
Death in sarcoidosis usually occurs secondary to cardiac or CNS involvement.
