Interstitial lung disease
Diffuse interstitial lung disease encompasses a large number of disorders that are characterized by cellular infiltrates in a periacinar location. While some disease processes may cause significant injury to the underlying lung parenchyma (e.g. usual interstitial pneumonia), some do not (e.g. pulmonary eosinophilia).
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Clinical presentation
Interstitial lung disease generally produce the "3Cs": cough, clubbing of the nails and coarse crackles on auscultation 6.
Pathology
Etiology
The radiological appearances are not specific for the underlying cause of diffuse lung disease in many cases. It is therefore key to determine whether there is an underlying cause for the changes. A number of precipitants can cause diffuse interstitial disease such as:
- smoking 1
- organic dusts (causing extrinsic allergic alveolitis)
- inorganic dusts (causing pneumoconioses)
- gases or fumes
- drugs
- radiation
- Infection
Eliciting a history of underlying systemic disease is also helpful since they may involve the lungs in a diffuse and infiltrative manner. Examples include:
- granulomatous diseases, e.g. sarcoidosis, Langerhans cell histiocytosis
- neoplasia
- primary, e.g. lymphoma, other lymphoproliferative diseases
- secondary, e.g. pulmonary metastases, lymphangitis carcinomatosis
- vasculitis
- inherited diseases, e.g. neurofibromatosis
- autoimmune and collagen vascular diseases 3
- miscellaneous, e.g. amyloidosis, alveolar proteinosis
Where a cause is not determined, the idiopathic interstitial pneumonias (IIP) should be considered:
- usual interstitial pneumonia (UIP): idiopathic pulmonary fibrosis
- cryptogenic organising pneumonia (COP): previously termed BOOP
- non-UIP IIP
- non-specific interstitial pneumonia (NSIP): non-smokers
- respiratory bronchiolitis-interstitial lung disease (RB-ILD): smokers
- desquamative interstitial pneumonia (DIP): end state of RB-ILD
- lymphoid interstitial pneumonia (LIP): women
- acute interstitial pneumonitis (AIP)
- other entities
Mnemonic: All Idiopathic Chronic Lung Diseases aRe Nonspecific
Radiographic features
The diffuse lung diseases tend to cause infiltrative opacification in the periphery of the lung. As the name of the group of diseases suggests, they are diffuse. While the consolidation or ground-glass change is usually bilateral, it may be localised, e.g. radiation pneumonitis.
Related Radiopaedia articles
Interstitial lung disease
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interstitial lung disease
- drug-induced interstitial lung disease
- hypersensitivity pneumonitis
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idiopathic interstitial pneumonia (mnemonic)
- acute interstitial pneumonia (AIP)
- cryptogenic organising pneumonia (COP)
- desquamative interstitial pneumonia (DIP)
- idiopathic non-specific interstitial pneumonia (NSIP)
- idiopathic pleuroparenchymal fibroelastosis
- lymphoid interstitial pneumonia (LIP)
- respiratory bronchiolitis–associated interstitial lung disease (RB-ILD)
- usual interstitial pneumonia / idiopathic pulmonary fibrosis (UIP/IPF)
- pneumoconioses