Interstitial Lung Disease Flashcards
What is some examples of interstitial lung disease?
- Usual Interstitial Pneumonia (UIP)
- Non-specific Interstitial Pneumonia (NSIP)
- Extrinsic Allergic Alveolitis
- Sarcoidosis
- Several other conditions
What types of lung disease is Interstitial Lung disease?
Typically, restrictive lung diseases on pulmonary function tests
What is the commonest type of interstitial lung disease?
Commonest type is Idiopathic Pulmonary Fibrosis
What are investigations does for interstitial lung disease?
- ANA – antinuclear antibody
- ENA – extractable nuclear anitgens
- Rh F – rheumatoid factor
- ANCA - vasculitis
- Anti-GBM – Goodpasture’s syndrome
- ACE
- IgG to serum precipitins (HIV)
What are examination features of Idiopathic Pulmonary Fibrosis?
- Clubbing
- Reduced chest expansion
-
Auscultation
- Fine inspiratory crepitations (like pulling Velcro slowly)
- Usually best heard basal / axillary areas
- Cardiovascular – may be features of pulmonary hypertension
What causes Idiopathic Pulmonary Fibrosis in most cases?
- Usually Interstitial Pneumonia
- It is the most common histological finding
How does Usual Intertitial Pneumonia cause Idiopathic Pulmonary Fibrosis?
- Wound healing mechanism in response to damage leads to over-production of fibroblasts and deposition of increased extracellular matrix in the interstitium with little inflammation
- Structural integrity of lung parenchyma is therefore disrupted. There is loss of elasticity, ability ot perform gas exchange impaired leading to progressive respiratory failure
What factors can be involved in pathology of Idiopathic Pulmonary Fibrosis?
- Inhalational
- Viruses (EBV)
- Drugs (methotrexate, nitrofurantoin, bleomycin)
What is the imaging of choice in Idiopathic Pulmonary Fibrosis?
High Resolution CT scan is the diagnostic imaging of Choice
What are findings shown on High Resolution CT scanning?
- Basal Distribution: abnormalities more pronounced at the bases
- Subpleural Reticulation: reticulation most evident in lung peripheries
- Traction Bronchiectasis: distortion of normal lung architect by fibrosis pulling airways open and causing bronchiectasis
- Honeycombing
What are some investigations for Idiopathic Pulmonary Fibrosis?
- Respiratory function test shows restrictive pattern
- Blood Test including antinuclear antibodies and rheumatoid factor to exclude autoimmune rheumatic disease
- HRCT is imaging of Choice
- Chest X-ray
- Bronchoalveolar Lavage is only necessary if an infective or malignant cause is suspected.
- Histological Confirmation necessary in some patients under VATS
How is Idiopathic Pulmonary Fibrosis managed?
- Pirfenidone
- Nintedanib
What is the cause of Extrinsic Allergic Alveolitis?
- Inhalation of organic antigen to which the individual has been sensitised
- One of the most common causes is farmer’s lung which can affect 9% of farmers in humid climates.
What is the pathogenesis of Extrinsic Allergic Alveolitis?
- Allergic response which involves both cellular immunity and deposition of immune complexes causing foci of inflammation through activation via classival pathway can also lead to inflammation by directly activating the alternate complement pathway.
- Leads to chronic inflammatory infiltrate, poorly defined interstitial granulomas, Interstitial fibrosis and honey comb change in chronic disease
What is the clinical presentation of Extrinsic Allergic Alveolitis?
ACUTE
- Short period from exposure(4-8 hrs).
- Usually reversible: spontaneously settle 1-3 days but can recur
- Fever common
CHRONIC
- Chronic exposure (months – years).
- Less reversible.
- Finger clubbing may be present and progression to irreversible fibrosis
