Interstitial Lung dz Flashcards
Pathophysiology of ILD
Interstitial thickening (fibrosis, inflammation) –>
Restrictive ventilatory defect (reduced TLC)
Hypoxemia: due to V/Q mismatch: low V/Q bc lung walls are not compliant; you ventilate the healthy alveoli more than the stiff, sick alveoli
Diffusion impairment due to thickened interstitium** **–> decreased exercise tolerance
Alveolar hyperventilation: triggered by hypoxemia, abnormal mechanics and load
Vascular dz: intimal hyperplasia, medial hypertrophy, pulmonary htn (consequence of interstitial lung dz, but not severe)
What is the definition of ILD?
Interstitial lung dz: a group of non-infectious, non-neoplastic lung diseases each characterized by varying degrees of inflammation and/or fibrosis of the parenchyma of both lungs
What are the subcategories of ILD’s?
Known cause: connective tissue dz, occupational causes, drug SE
Idiopathic interstitial pneumonias: 7 total
Granulamtous: sarcoidosis, hypersensitivity pneumonitis, infections
Other forms of ILD: not fibrosis or inflammation
What are the 7 IIP’s?
Idiopathic pulmonary fibrosis: typical form of the dz
Non-specific interstitial pneumonia: inflammation & or fibrosis
Desquamative interstitial pneumonia: smoking related
Respiratory bronchiolitis-ILD: smoking related
Cryptogenic organizing pneumonia
Acute interstitial pneumonia: uncommon
Lymphocytic interstitial pneumonia: uncommon
For known causes of ILD, what are the known injurious agents?
Drugs i.e. amiodarone, chemotherapy for Hodgkin’s dz, methotrexate, nitrofurantoin (antib)
Radiation induced
Connective Tissue Diseases: autoimmune mediated scar tissue deposition in the lungs- RA, systemic sclerosis, idiopathic inflammatory myopathies, dermatomyositis
Occupational/environmental: asbestosis, coal workers pneumoconiosis, silicosis; birds, molds
What are the similaritis and differences between different ILD’s?
Similarities: progressive, exertional dyspnia, non-productive cough, bibasilar crackles, restrictive vent defect, impaired gas exchange, abnormal lung imaging
Differences: extrapulmonary findings, sarcoidosis, conn tissue dz, pattern on lung CT, histopathology, serologies
What tests do you do when you suspect ILD?
PFT’s: spirometry, lung volumes, DLCO
Chest HRCT
6 Minute Walk testing
Echocardiogram
Lab data: antibodies for autoimmunity, bird/lung antigens, kidney function tests, hypersensitivity pneumonitis panel
Which lung dz do you see clubbing?
Pulmonary fibrosis, lung cancer
NEVER seen in COPD
Which skin conditions do you see in ILDs?
Detrons papules = erythematous, shiny skin esp over the joints = dermatomyocitis (dz that affects skin, lung, and skeletal sm musc)
Reynaud’s: autoimmune dz –> spontaneous/cold induced vasoconstriction –> pallor of digits, cyanosis
Sclerodactyly: thickening & ulceration of the skin; no hair on digits, thin tough skin = systemic sclerosis
- *Erythema nodosum**: red painful areas on the legs
- seen in many conditions including sarcoidosis
Lupus pernio: purple plaques on face; seen in sarcoidosis
Ground glass opacity
Reticular opacities
Intersecting lines, white areas of increased attenuation, looks like white lines
Seen in other conditions but usually indicates ILD
Honeycombing
How do you treat ILD?
Avoid lung injury i.e. inhaled agents, offending drug
Anti-inflammatory therapy: treat underlying inflammatory dz, corticosteroids
No therapies are effective for lung fibrosis
Lung transplantation
O2 therapy
PUlm rehab
Vaccinations
Treat resp infections
Drug therapy: NAC (anti-tylenol)
What is usual interstitial pneumonia?
Pattern seen on either high resolution CT or on histopatholgy. They are associated with one another.
Restrictive disease
HCRT: subpleural, lower lobe reticular changes, honeycombing, traction bronchiectasis
Histopathological pattern: spared & densely fibrotic lung side by side
- peripheral lobular fibrosis, small foci of fibroblastic proliferation, sparing of airways
- areas of fibrosis with areas of spared lung in between: grossly, looks like nodules due to preserved v. spared lung areas; histological pattern is like this too
- scarred areas of interstitial fibrosis
- “honeycomb lung” both grossly and microscopically
What is idiopathic pulmonary fibrosis?
Most common IIP
Thickening of alveolar walls & interstitium due to fibrosis
Radiologically: UIP (if you see this, diagnostic for IIP)
Histopathology: usual interstitial pneumonia (UIP)
- if you suspect IPF, but HRCT is neg
- if this is neg, rule out IPF
- if this is positive, consider IPF as diagnosis
Risk factors: older age, male gender, cig smoking, fam hist
