Usual interstitial pneumonia
Usual interstitial pneumonia (UIP) refers to a morphological pattern of interstitial lung disease. In the past the term UIP was used to sometimes synonymously used with idiopathic pulmonary fibrosis (IPF) while more lately the term idiopathic pulmonary fibrosis is applied solely to the clinical syndrome associated with the morphologic pattern of UIP and specifically excludes entities such as non specific interstitial pneumonia (NSIP) and desquamative interstitial pneumonia DIP 1.
The histologic diagnosis of UIP is based on temporal heterogeneity : which is the identification of fibrotic lesions at different stages (fibroblastic foci, mature fibrosis, and honeycombing) within the same biopsy specimen 1. On a typical biopsy, there are areas of normal lung alternate with interstitial inflammation and honeycombing .
- connective tissue disorders
- rheumatoid arthritis : UIP is considered to be the dominant pattern in those with rheumatoid arthritis who have concurrent interstitial lung disease 3.
- systemic sclerosis : can have either a UIP or NSIP (commoner) pattern 4.
- polymyositis / dermatomyositis : those with these can have a UIP, NSIP or BOOP pattern 4.
- mixed connective tissue disease : can have either a UIP or NSIP pattern 4.
- asbestos related interstitial lung disease : asbestosis 1
Location - distribution
The distribution of UIP on CT images is typically characteristically with an apico-basal gradient with basal and peripheral predominance, although it is often patchy.
Plain film - Chest radiograph
Plain film features are non specific. While chest radiographs can be even be normal in patients with very early disease, in advanced disease, it may show decreased lung volumes and sub-pleural reticular opacities that increase from the apex to the bases of the lungs.
When describing imaging features, the term UIP type pattern is often used.
The positive predictive value of CT in the diagnosis of UIP is high and ranges from ~ 70 - 100 1.
As observed on a pathology specimen, cross sectional imaging also reveals heterogeneous, with areas of fibrosis alternating with areas of normal lung 5.
Typical features include 1,5
- the presence of reticular opacities, often associated with traction bronchiectasis (considered a very good differentiating feature from patients with NSIP and concurrent emphysema 6.
- honeycombing : common.
- ground-glass opacities : common but are usually less extensive than the reticular pattern.
- architectural distortion, which reflects lung fibrosis, is often prominent.
- lobar volume loss is seen in cases of more advanced fibrosis.
Treatment and prognosis
In patients with UIP, areas of ground-glass attenuation tend to increase in extent or progress to fibrosis despite treatment 8.The average rate of progression of honeycombing in patients with idiopathic usual interstitial pneumonia according to one study was 0.4% of lung volume per month 7 .
If there is added upper lobe predominant emphysematous change consider
- 1. Lynch DA, Travis WD, Müller NL et-al. Idiopathic interstitial pneumonias: CT features. Radiology. 2005;236 (1): 10-21. doi:10.1148/radiol.2361031674 - Pubmed citation
- 2. Akira M, Inoue Y, Kitaichi M et-al. Usual interstitial pneumonia and nonspecific interstitial pneumonia with and without concurrent emphysema: thin-section CT findings. Radiology. 2009;251 (1): 271-9. doi:10.1148/radiol.2511080917 - Pubmed citation
- 3. Jeong YJ, Lee KS, Müller NL et-al. Usual interstitial pneumonia and non-specific interstitial pneumonia: serial thin-section CT findings correlated with pulmonary function. Korean J Radiol. 6 (3): 143-52. Korean J Radiol (link) - Free text at pubmed - Pubmed citation
- 4. Kim EA, Lee KS, Johkoh T et-al. Interstitial lung diseases associated with collagen vascular diseases: radiologic and histopathologic findings. Radiographics. 2002;22 Spec No : S151-65. Radiographics (full text) - Pubmed citation
- 5. Mueller-mang C, Grosse C, Schmid K et-al. What every radiologist should know about idiopathic interstitial pneumonias. Radiographics. 27 (3): 595-615. doi:10.1148/rg.273065130 - Pubmed citation
- 6. Akira M, Inoue Y, Kitaichi M et-al. Usual interstitial pneumonia and nonspecific interstitial pneumonia with and without concurrent emphysema: thin-section CT findings. Radiology. 2009;251 (1): 271-9. doi:10.1148/radiol.2511080917 - Pubmed citation
- 7. Akira M, Sakatani M, Ueda E. Idiopathic pulmonary fibrosis: progression of honeycombing at thin-section CT. Radiology. 1993;189 (3): 687-91. Radiology (abstract) - Pubmed citation
- 8. Hartman TE, Primack SL, Kang EY et-al. Disease progression in usual interstitial pneumonia compared with desquamative interstitial pneumonia. Assessment with serial CT. Chest. 1996;110 (2): 378-82. doi:10.1378/chest.110.2.378 - Pubmed citation
- 9. Du bois R, King TE. Challenges in pulmonary fibrosis x 5: the NSIP/UIP debate. Thorax. 2007;62 (11): 1008-12. doi:10.1136/thx.2004.031039 - Free text at pubmed - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Usual interstitial pneumonitis (UIP)||✗|
|Usual interstitial pneumonia (UIP)||✗|
|Usual interstitial pneumonitis||✗|