Interstitial Lung Diseases Flashcards

1
Q

The interstitium

A
Alveolar endothelium
Capillary endothelium
Basement membrane
Connective tissue
In disease, it can be thickened by fluid, cells, fibrosis
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2
Q

Extracellular matrix

A

3D fibre mesh filled with macromolecules e.g. collagen/elastin
Functions: tensile strenght/elasticity, low resistance for effective gas exchange, tissue repair/modelling
In fibrosis, aberrant wound healing leads to excessive deposition in the interstitium

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3
Q

Classification

A

Environmental exposure: Occupational lung disease (silicosis, coal miners lungs, abestosis); hypersenstivity pneumonitis (mould and bird proteins are common causes)
Idiopathic: Idiopathic pulmonary fibrosis is the protypical ILD
Systemic Inflammatory Disease: connective tissue disease - ILD, sarcoidosis

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4
Q

Idiopathic Pulmonary Fibrosis - presentation

A

Symptoms and clinical signs often appear gradually and include:
slowly progressive exertional dyspnoea; non productive cough; dry, inspiratory bibasal crackles; +/- clubbing of fingers; abnormal pulmonary function test results

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5
Q

IPF summary

A

Unknown cause; causes progressive, irreversible fibrosis and is fatal; is limited to the lungs; affects lower peripheral lung; minimal inflammation; is a disease of older age; is more common in men; is more common in smokers; HRCT is mainstay of dx but lung biopsy may be needed

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6
Q

Management of IPF

A

Assess suitability for anti-fibrotic drugs (Pirfenidone or Nintedanib); can only be one prescribed by specialist centres; aim is to slow rate of disease progression
Criteria: diagnosis of IPF, FVC 50-80% predicted, often poorly tolerated
Assess suitability for lung transplant: age <65, no significant comorbidities

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7
Q

Hypersensitivity Pneumonitis

A

Diffuse inflammation of parenchyma in response to inhaled antigen - tends to involve upper lobes (bird fanciers, farmers lung, aspergillus, can be anything, antigen unknown in 50%)
Acute - SOB, cough, fever, malaise, crackles, often misdiagnosed
Subacute - gradual onset of symptoms, weight loss common
Chronic - insidous onset, incomplete resolution with removal of antigen, may lead to irreversible fibrosis
Serum Precipitins (circulating IgG antibody-antigen complexes - infinite number of possible antigens, may be positive in asymptomatic individuals, negative result doesn’t exclude HP
Drug induced - medication important to ask in history (nitrofurantoin, amiodarone, methotrexate)

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8
Q

Management of HP

A

Avoidance of inciting antigen
Usually steroid-responsive in early disease
May progress to irreversible fibrosis

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9
Q

Connective Tissue Disease-related ILD

A

Rheumatoid arthritis, siogrens, scieroderma, polymyositis
Younger patients
Female preponderance
Detained Hx: dry eyes/mouth, Raynaud’s, joint pain/swelling, rashes
Bloods: antinuclear antibodies, rheumatoid factor
Management: liaise with rheumatology, treat underlying disease (biologics, steroids, immunosuppression)

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10
Q

ILD Diagnosis

A

Clinical Assessment (CTD symptoms, drugs, exposures)
Bloods (antinuclear abs, rheumatoid factor, angiotensin-converting enzyme (ACE)
Spirometry (FEV, FEV/FVC ratio, gas transfer)
CXR (reticular shadowing)
HCRT pattern of disease (but only 60% are diagnostic)
Lung biopsy (enhances diagnosis, but risk often outweigh benefit, may differentiate IPF from other potentially reversible causes)

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11
Q

ILD treatment

A

MDT for diagnosis: resp physical, resp radiologist, rheumatologist, +/- specialist, histopathologist; combination of history, HRCT pattern of disease, autoimmune bloods
Treatment: remove cause, immunosuppression, anti-fibrotics for IPF

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12
Q

Sarcoid

A

Mutli-system granulomatous disorder - non-necrotising granulomas
Cause unknown (3x more common in Afro-Caribbeans & more severe disease)
Disease of the young (75% if cases 30-60 yrs)
Unpredictable clinical course

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13
Q

Histology of Sarcoid

A

Characterised by granulamatous inflammation
Unknown foreign antigen stimulates immune response including CD4+ T 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 sarcoidosis

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14
Q

Common Presentations of Sarcoidosis)

A

Chest: cough, SOB, wheeze, incidental finding on CXR (all especially common in pulmonary sarcoidosis - and some systemic symptoms)
Skin: erythema nodosum, lupus pernio, plaques, nodules
Eyes: anteror uveitis
Lymph node biopsy: performed for suspected malignancy
Hypercalcaemia
Peripheral nerves: Bell’s palsy, mononeuropathies
Systemic: fever, sweats, weight loss, fevers, arthralgia

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15
Q

Lofgren’s Syndrome

A
Erythema nodosum
Bilareral Hilar Lymphadenopathy
Arthralgia
Excellent prognosis
Usually self limiting
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16
Q

Sarcoidosis Diagnosis

A

No single diagnostic test
Combination of clinical picture, exclusion of alternative diagnoses and ideally biopsy of affected tissue
Baseline tests: renal and liver function, calcium, serum ACE, CXR, ECG
Serum Angiotensin Converting Enzyme (ACE): secreted by activated alveolar macrophages in granulomas, low sensitivity (60%), poor specificity, polymorphisms in ACE gene leads to variation of ACE levels in peripheral blood, no correlation with CXR stage of disease
Biopsy everything: lymoh nodes, skin, endobronchial

17
Q

Sarcoidosis Treatment

A

Major organ involvement: ocular disease not responding to topical treatment, cardiac, neruological
Less clear cut for pulmonary disease: often less severe, short term symptomatic benefit, long term effect on natural history of disease not known
Corticosteroids for 6-24 months are mainstay: inhaled corticosteroids for symptomatic benefit, additional immunosuppressants

18
Q

Obstructive Spirometry

A

Indicates the problem is in airways
Useful diagnostically (reversible/fixed airflow obstruction = asthma/COPD)
Oonly a few other diseases of airways (bronchiectasis, obliterative bronchiolitis)

19
Q

Restrictive Spirometry

A

Indicates a problem, but not useful diagnostically
Useful for monitoring change (acutely = Guillain Barre, chronically = MND, indicates risk of ventilatory failure)
Severity indicator for ILD
Treatment criteria for IPF (anti-fibrotics only if FVC 50-80% of predicted)
Restriction of lung expansion of loss of lung volume
Directly measured by TLC (requires lung function lab)
FVC reflects the TLC (done in clinic)