interstitial lung diseases Flashcards
1
Q
what is interstitial shadowing? 3
A
- reticular pattern
- too many lung markings
- may be local or may diffuse
2
Q
what is the interstitium? 5
A
- supporting structures of the lung
- alveolar endothelium
- capillary endothelium
- basement membrane
- connective tissue
3
Q
what can the interstitium be thickened by? 3
A
- fluid
- cells
- fibrosis (aberrant wound healing leads to excessive deposition in the interstitium)
4
Q
what is the extracellular matrix?
functions? 3
A
3D fibre mesh filled with macromolecules (collagen, elastin)
- tensile strength/elasticity
- low resistance for effective gas exchange
- tissue repair/modelling
5
Q
name environmental exposure ILDs? 2
A
- occupational lung disease
- hypersensitivity pneumonitis
6
Q
name an idiopathic ILD?
A
-idiopathic pulmonary fibrosis (prototypical ILD)
7
Q
name 2 systemic inflammatory disease?
A
- connective tissue disease
- sarcoidosis
8
Q
what is the presentation of idiopathic pulmonary fibrosis? 5
A
- slowly and progressive exertional dyspnoea
- non productive cough
- dry inspiratory bibasal velcro crackles
- +/- clubbing on fingers
- abnormal pulmonary function test results- restriction and impaired gas exchange
9
Q
what is the HRCT pattern of idiopathic pulmonary fibrosis? 4
A
- basal distribution
- sub-pleural
- traction bronchiectasis
- honeycombing
10
Q
give a general summary of IPF? 9
A
- unknown cause
- causes progressive, irreversible fibrosis and is fatal
- limited to the lungs
- affects lower and peripheral lung
- minimal inflammation–> no role for steroids
- is a disease of older age
- more common in men
- more common in smokers
- biopsy may be needed
11
Q
describe IPF in the UK? 5
A
600 new cases each year
- 1/100 deaths in the UK
- median survival is 3 years from diagnosis
- 20% still alive at 5 year
- no reliable way to predict prognosis so patients live with massive uncertainty
12
Q
what is the management for IPF? 3
A
- assess suitability for anti-fibrotic drugs: can only be prescribed at specialist centres, aim is to slow disease progression, often poorly tolerated–> weight loss, GI upset
- assess suitability for lung transplant, <65, no significant co-morbidities
- offer best supportive care to all
13
Q
what is hypersensitivity pneumonitis? 6
A
- diffuse inflammation of parenchyma in response to inhaled oxygen
- involve upper lobes
- bird droppings
- farmers lung= thermophilic fungi
- aspergillus= ubiquitous fungi
- antigen is unknown in 50% of cases
14
Q
what is the presentation of hypersensitivity pneumonitis? 4
A
-acute= SOB, cough, fever, crackle within 4-6 hours of heavy exposure, often misdiagnosed as infection
most cases develop only after may years of continuous or intermittent inhalation of inciting agent
- subacute= gradual onset of symptoms, weight loss is common
- chronic= insidious onset, history of acute episodes may be absent, incomplete resolution with removal of antigen, may lead to irreversible fibrosis
15
Q
how do we diagnose hypersensitivity pneumonitis ? 4
A
- serum precipitins (circulating IgG antibody-antigen complexes) to specific antigen may be helpful
- infinite number of possible antigens
- may be positive in asymptomatic individuals
- negative results do not exclude HP
16
Q
how do we manage hypersensitivity pneumonitis? 3
A
- avoidance of enticing antigen
- usually steroid responsive in early disease
- may progress to irreversible fibrosis
17
Q
describe drug induced ILD? 4
A
- medication history is very important
- many drugs but the most common are nitrofurantoin, amiodarone and methotrexate
- always consider if medication may be implicated-> association between initiation of drug and disease onset is important
- ILD may develop months-years after starting the drug
18
Q
describe connective tissue disease related ILD? 7
A
- Rheumatoid arthritis
- Scleroderma
- Sjogren’s
- Polymyositis
- Younger patients
- Female preponderance
- Detailed Hx: dry eyes/ mouth, joint pain/ swelling, rashes
19
Q
describe what you would see in the bloods of connective tissue disease related ILD?
A
- antinuclear antibodies (ANA)
- rheumatoid factor (RF)
20
Q
how do we manage connective tissue disease related ILD? 2
A
- liaise with rheumatology
- treat underlying disease (biologics, steroids, immunosuppression)
21
Q
how do we diagnose ILD (summary)? 4
A
- clinical assessment–> is there an identifiable cause? CTD symptoms, drugs, exposures
- bloods –> antinuclear antibodies, rheumatoid factors, angiotensin-converting enzyme, spirometry/lung function tests
- CXR–> reticular shadowing
- HRCT pattern of disease—> the cornerstone of diagnosis, only 60% are diagnostic
- lung biopsy–>enhances diagnosis but risk often outweighs benefit, may differentiate IPF from other potentially reversible causes
22
Q
how do we treat ILD (summary)? 3
A
- remove cause
- immunosuppression
- anti-fibrotics for IPF
23
Q
what is sarcoid? 7
A
- Multisystem granulomatous disorder
- Non necrotising granulomas
- Cause is unknown
- 3x more common in Afro-Caribbean’s, more sever disease
- Some familial clusters
- Disease of the young (30-60)
- Unpredictable clinical course
24
Q
what is the histology of sarcoid? 7
A
- Characterised by granulomatous inflammation
- Unknown foreign antigen stimulates immune response including:
CD4+ T cells - Alveolar macrophages
- Multi-nucleate giant cells
- Organised into granulomas
- Granulomas occur in TB and fungal infections, but in sarcoidosis they are non-necrotising
- A biopsy demonstrating granulomas along with clinical picture is needed to confidently diagnose sarcoidosis
25
describe lofgren's syndrome? 5
- Erythema nodosum
- Bilateral lymphadenopathy
- Arthralgia
- Excellent prognosis
- Usually, self-limiting
26
describe pulmonary sarcoidosis? 5
- May be symptomatic
- Cough
- Dyspnoea with exertion
- Chest tightness
- Systemic symptoms: fatigue, sweats, weight loss, fever
27
how do we diagnose pulmonary sarcoidosis? 9
- No single diagnostic test
- Combination of clinical picture, exclusion of alternative diagnoses and ideally biopsy of affected tissue
- Baseline tests: renal function, liver function, calcium, serum ACE, CXR, ECG
- Serum angiotensin-converting enzyme (ACE):
- Secreted by activated alveolar macrophages in granulomas
- Low sensitivity, poor specificity
- Polymorphisms in ACE gene variation in peripheral blood ACE levels
- No correlation with CXR stage of disease
- Biopsy everything! Skin, lymph nodes, blind endobronchial biopsies
28
how do we treat pulmonary sarcoidosis with major organ involvement? 3
- ocular disease not responding to topical treatment
- cardiac
- neurological
29
how do we treat pulmonary sarcoidosis with pulmonary disease? 5
- Often less severe than extra-thoracic disease with spontaneous remission common
- Short-term symptomatic benefit
- Long term effect on natural history of disease is not known
- Corticosteroids for 6-24 months are mainstay:
inhaled corticosteroids may provide symptomatic benefit
- Additional immunosuppressants may be necessary
30
explain obstructive spirometry? 4
- Indicates the problem is in the airways
- Useful diagnostically:
- Reversible airflow of obstruction asthma
- Fixed airflow obstruction in a smoker COPD
only a few other diseases of the airways
31
explain restrictive spirometry? 7
- Indicates there is a problem, but is not useful diagnostically
- Useful for monitoring change (acutely, chronically, indicates risk of ventilatory failure)
- Severity indicator for ILD
- Treatment criteria for IPF anti fibrotic only if FVC 50-80% predicted
- Restriction of lung expansion or loss of lung volume
- Directly measured by TLC requires a lung function lab
- FVC reflects the TLC? Can be done in clinic and is useful for disease monitoring
32
explain lung function tests in ILD? 6
- Fibrotic lungs are small and stiff
- Higher elastic recoil than expected for volume
- FEV1/FVC ratio may be high, but may be normal
- Decreased TLCO (gas transfer)
- Impaired gas exchange due to disruption of alveolar- capillary interface
- Reduced total surface area for gas exchange
