interstitial lung disease Flashcards
what is interstitial shadowing
Reticular eg linear, lace like patter
Too many lug markings
May be focal or diffuse
what is the interstitium
Refers to supporting structures of the lung
Includes: alveolar endothelium, capillary endothelium, basement membrane, connective tissue
In disease it can be thickened by
Fluid, cells, fibrosis
what is the extracellular matrix
3D fibre mesh filled with macromolecules eg. Collagen, elastin
Several functions
Tensile strength/elasticity
Low resistance for effective gas exchange
Tissue repair/remodelling
In fibrosis, aberrant wound healing leads to excessive deposition in the interstitium
how are ILDs classified
Environmental exposures Occupational lung disease Silicosis (silica exposure) Coal miners lung (coal dust exposure) Asbestosis (asbestos exposure) Hypersensitivity pneumonitis (mould and bird proteins are common causes) Idiopathic Idiopathic pulmonary fibrosis is the prototypical ILD Systemic inflammatory diseases Connective tissue disease-ILD Sarcoidosis
how can classification be simplified
connective tissue disease, hypersensitivity pneumonitis, sarcoidosis, drug, occupational
no cause- idiopathic
how does idiopathic pulmonary fibrosis present
Symptoms and clinical signs of IPF appear gradually and include
Slowly progressive exertional dyspnoea
Non-productive cough
Dry, inspiratory bibasal ‘velcro’ crackles
Possibly clubbing
Abnormal pulmonary function test results (restriction and impaired gas exchange)
what is the IPF HRCT pattern
basal distribution, sub pleural, honeycombing, traction bronchiectasis
if present - no biopsy needed
how can IPF be summarised
Progressive, irreversible fibrosis and is fatal
Limited to lungs – unlike other ILDs like sarcoidosis
Affects lower and peripheral lungs
Minimal inflammation – no role for steroids
Disease of older age (median age of 66)
2x as common in men
More common in smokers (60%)
HRCT = most diagnosis but lung biopsy may be needed
how does IPF impact the UK
Approx 6000 new cases each year
Increasing by 5% each year
>32000 living with it
1/100 deaths
what is the prognosis of IPF
Median survival is 3 years from diagnosis
But 20% still alive after 5
No reliable way to predict
Live with considerable uncertainty
How is IPF managed
Assess suitability for anti fibrotic drugs
Pirfenidone or nintedanib
Can only be prescribed by specialist centres
Aim to slow rate of progression
what is the criteria for IPF treatment
Diagnosis of IPF
FVC 50-80% predicted
drugs often poorly tolerated – weight loss, GI upset and photosensitivity
Assess suitability for lung transplant (<65, no sig comorbidities)
Offer best supportive care to all
how can the best supportive care for IPF be provided
stepwise decline- intervene and treat (acute infection, PE, pneumothorax, acute exacerbation) treat comorbidities (GORD, COPD, lung cancer) Palliate symptoms (LTOT, Pulmonary rehab, benzos, opiates) refer to palliative care
what is hypersensitivity pneumonitis
Diffuse inflammation of parenchyma is response to inhaled antigen – teds to involve upper lobes Bird-fanciers (bird droppings) Farmers lung (thermophilic) Aspergillus (ubiquitous fungus) Antigen unknown in 50%
how does HP present
Acute
SOB, cough, fever and crackles within 4-6 hours of heavy exposure
Often misdiagnosed as infection
Most develop after years of continuous or intermittent inhalation of inducing aget
Sub-acute
Gradual onset of symptoms, wight loss common
Chronic
Insidious onset, history of acute episodes may be absent
Incomplete resolution with removal of antigen
May lead to irreversible fibrosis
how is HP diagnosed
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 result does not exclude HP
how is HP managed
Avoid inciting antigen
Usually steroid-responsive in early disease
May progress to irreversible fibrosis
how is drug-induced ILD diagnosed
Medication history important – specific questions
Many common drugs are nitrofurantoin, amiodarone, methotrexate
Always consider if medication may be implicated
Association between initiation of drug and onset of disease important but ILD may develop months-years after starting the drug
what is connective tissue disease-related ILD
Rheumatoid arthritis, sjogrens, scieroderma, polymyositis
Younger patients, female predominance
Detailed history – dry eyes/mouth, raynaud’s, joint pain/swelling, rashes
Bloods – antinuclear antibodies, rheumatoid factor
Management – liaise with rheumatology, treat underlying disease (biologics, steroids, immunosuppression)
How are ILDs diagnosed
Clinical assessment – identifiable cause
CTD symptoms, drugs, exposures
Bloods – ANA, RF, angiotensin-converting enzyme (ACE)
Spirometry/lung function tests
FVC, FEV1/FVC ratio (normal or high), gas transfer (may have co-existent COPD)
CXR – reticular shadowing
HRCT pattern of disease – cornerstone of diagnosis but only 60% are diagnostic
Lung biopsy – enhances diagnosis but risk often outweighs the benefit, may differentiate IPF from other potentially reversible causes
how are ILDs treated
MD1 for diagnosis
Respiratory physician, respiratory radiologist, rheumatologist (+ specialist histopathologist)
Combo of history, HRCT pattern of disease, auto-immune bloods
Remove cause.
Immunosuppression (prednisolone, hydroxychloroquine, mycophenolate mofetil, methotrexate)
Anti-fibrotics for IPF
what is sarcoidosis
Multisystem granulomatous disorder – non-necrotising granulomas
Cause unknown – 3x more common in afro-caribbeans, more severe disease, some familial clusters
Disease of the young – 75% 30-60 years
Unpredictable clinical course
what is the histology of sarcodosis
Characterised by granulomatous inflammation
Unknown foreign antigen stimulates immune response including
CD4+ cells, alveolar macrophages, multi-nucleate giant cells
Organise 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
how does sarcoidosis manifest
Can effect any organ – lung involvement 90%
Lung and thoracic lymph nodes – dyspnoea, cough, chest pain, pulmonary hypertension, mixed pulmonary function test, abnormalities (obstruction, restriction, diffusion, deficits)
