Forms of Interstitial Pneumonia

 

The idiopathic interstitial pneumonias (IIPs) represent several idiopathic subtypes of interstitial lung disease (ILD) including:

• idiopathic pulmonary fibrosis/ usual interstitial pneumonia (IPF/UIP)

• cryptogenic organizing pneumonia (COP)

• nonspecific interstitial pneumonia (NSIP)

• respiratory bronchiolitis-interstitial lung disease (RB-ILD)

• desquamative interstitial pneumonia (DIP)

• acute interstitial pneumonia (AIP)¹ 

 

These subtypes of IIP differ in their clinical, radiologic, and histopathologic presentation.  IPF/UIP, by far the

 

most common form of IIP, is histopathologically defined by the presence of the prototypical form of pulmonary fibrosis, usual interstitial pneumonia (UIP) pathology with a fibrosing interstitial pneumonia characterized by a pattern of heterogeneous, subpleural patches of fibrotic, remodeled lung.²

 

Other IIPs, such as desquamative interstitial pneumonia (DIP), occur earlier in life, and have a lower mortality, and are generally associated with a more cellular interstitial pneumonia with or without accompanying fibrosis.

 

By contrast, nonspecific interstitial pneumonia (NSIP), a pattern of IIP that likely comprises more than one disease, is most commonly characterized by interstitial fibrosis but in a more uniform pattern than UIP, and carries a better prognosis than IPF/UIP. ^3,4

 

 

All forms of IIP have a somewhat unpredictable prognosis and can progress to end stage lung disease.^1,2   The "classical" high resolution CT (HRCT) pattern for IPF and the indeterminant HRCT pattern can share a similar UIP (usual interstitial pneumonia) pattern of histology^49,50 (Hunninghake ,Raghu 99).

 

 

 

 

 

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References

1. Travis et al. American ThoracicSociety/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias. This joint statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) was adopted by the ATS board of directors, June 2001 and by the ERS Executive Committee, June 2001. Am J Respir Crit Care Med. 165(2):277-304 (2002).

2. King et al. International consensus statement idiopathic pulmonary fibrosis: diagnosis and treatment. Amer J Resp Crit Care Med. 161:646-664 (2000).

3. Daniil et al., A histologic pattern of nonspecific interstitial pneumonia is associated with a better prognosis than usual interstitial pneumonia in patients with cryptogenic fibrosing alveolitis. Am J Respir Crit Care Med. 160(3):899-905 (1999).

4. Nicholson et al., D M Hansell, A U Wells, The prognostic significance of the histologic pattern of interstitial pneumonia in patients presenting with the clinical entity of cryptogenic fibrosing alveolitis. Am J Respir Crit Care Med. 162(6):2213-2217 (2000).

5. Hunninghake et al., Utility of a lung biopsy for the diagnosis of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 164(2):193-196 (2001).

6. Raghu et al., The accuracy of the clincal diagnosis of new-onset idiopathic pulmonary fibrosis and other interstitial lung disease: a prospective study. (1999).***