Usual interstitial pneumonia
Updates to Article Attributes
Usual interstitial pneumonia (UIP) refers to a morphological pattern of interstitial lung disease. In the past the term UIP was used synonymously 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.
Pathology
The histologic diagnosis of UIP is based on temporal and spacial heterogeneity, which is the identification of fibrotic lesions at different stages (fibroblastic infiltrates, mature fibrosis, and honeycombing) within the same biopsy specimen 1. On a typical biopsy, there are areas of normal lung alternating with interstitial inflammation and honeycombing.
Associations
- 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
(scelroderma(scleroderma): can have either a UIP or NSIP (commoner) pattern 4 - polymyositis/dermatomyositis: those with these can have a UIP, NSIP or COP pattern 4
- mixed connective tissue disease: can have either a UIP or NSIP pattern 4
- asbestos related interstitial lung disease: asbestosis 1
- chronic hypersensitivity pneumonitis
- radiation
- drug toxicity
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.
Radiographic features
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 subpleural reticular opacities that increase from the apex to the bases of the lungs. usually due to more extensive involvement of the lower lobes, the major fissure is shifted inferiorly; this is best seen on the lateral chest radiograph.
HRCT
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 heterogeneity, with patchy areas of fibrosis alternating with areas of normal lung 5.
Typical features include 1,5:
- the presence of reticular opacities in the immediate subpleural lung, often associated with honeycombing and/ or traction bronchiectasis, with peripheral and lower lobe predominance is considered a very good differentiating feature from patients with NSIP and concurrent emphysema 6
- ground-glass opacities: usually less extensive than the reticular pattern and almost never seen in isolation - usually happens in areas of reticulation or honeycombing
- lung architectural distortion: which reflects lung fibrosis and 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. In those with more active inflammation involving the pulmonary interstitium there is faster progression of honeycombing in long-term follow-up 10. 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 .
Differential diagnosis
A key imaging differential on cross sectional imaging would be non specific interstitial pneumonia pattern (especially fibrotic non specific interstitial pneumonia)
If there are added upper lobe predominant emphysematous changes also consider:
-<p><strong>Usual interstitial pneumonia (UIP) </strong>refers to a morphological pattern of <a href="/articles/interstitial-lung-disease">interstitial lung disease</a>. In the past the term UIP was used synonymously with <a href="/articles/idiopathic-pulmonary-fibrosis">idiopathic pulmonary fibrosis</a> (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 <a href="/articles/non-specific-interstitial-pneumonia-1">non specific interstitial pneumonia (NSIP</a>) and <a href="/articles/desquamative-interstitial-pneumonia">desquamative interstitial pneumonia (DIP</a>) <sup>1</sup>.</p><h4>Pathology</h4><p>The histologic diagnosis of UIP is based on temporal and spacial heterogeneity, which is the identification of fibrotic lesions at different stages (fibroblastic infiltrates, mature fibrosis, and honeycombing) within the same biopsy specimen <sup>1</sup>. On a typical biopsy, there are areas of normal lung alternating with interstitial inflammation and honeycombing.</p><h5>Associations</h5><ul>-<li>connective tissue disorders<ul>-<li>-<a href="/articles/rheumatoid-arthritis">rheumatoid arthritis</a>: UIP is considered to be the dominant pattern in those with rheumatoid arthritis who have concurrent interstitial lung disease <sup>3</sup>-</li>-<li>-<a href="/articles/scleroderma">systemic sclerosis (scelroderma)</a>: can have either a UIP or NSIP (commoner) pattern <sup>4</sup>-</li>-<li>-<a href="/articles/polymyositis">polymyositis</a>/<a href="/articles/dermatomyositis">dermatomyositis</a>: those with these can have a UIP, NSIP or COP pattern <sup>4</sup>-</li>-<li>-<a href="/articles/mixed-connective-tissue-disease">mixed connective tissue disease</a>: can have either a UIP or NSIP pattern <sup>4</sup>-</li>-</ul>-</li>-<li>asbestos related interstitial lung disease: <a href="/articles/asbestosis">asbestosis</a> <sup>1</sup>-</li>-<li><a href="/articles/chronic-hypersensitivity-pneumonitis">chronic hypersensitivity pneumonitis</a></li>-<li>radiation</li>-<li>drug toxicity</li>-</ul><h5>Location: distribution</h5><p>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.</p><h4>Radiographic features</h4><h5>Plain film: chest radiograph</h5><p>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 subpleural reticular opacities that increase from the apex to the bases of the lungs. usually due to more extensive involvement of the lower lobes, the major fissure is shifted inferiorly; this is best seen on the lateral chest radiograph.</p><h5>HRCT </h5><p>When describing imaging features, the term <strong>UIP type pattern</strong> is often used. </p><p>The positive predictive value of CT in the diagnosis of UIP is high and ranges from 70-100% <sup>1</sup>.</p><p>As observed on a pathology specimen, cross sectional imaging also reveals heterogeneity, with patchy areas of fibrosis alternating with areas of normal lung <sup>5</sup>.</p><p>Typical features include <sup>1,5</sup>:</p><ul>-<li>the presence of <a href="/articles/reticular-opacities">reticular opacities</a> in the immediate subpleural lung, often associated with <a href="/articles/honeycombing">honeycombing</a> and/ or <a href="/articles/traction-bronchiectasis">traction bronchiectasis</a>, with peripheral and lower lobe predominance is considered a very good differentiating feature from patients with NSIP and concurrent emphysema <sup>6</sup>-</li>-<li>-<a href="/articles/ground-glass-opacification">ground-glass opacities</a>: usually less extensive than the reticular pattern and almost never seen in isolation - usually happens in areas of reticulation or honeycombing</li>-<li>-<a href="/articles/lung-architectural-distortion">lung architectural distortion</a>: which reflects lung fibrosis and is often prominent</li>-<li>lobar volume loss is seen in cases of more advanced fibrosis</li>- +<p><strong>Usual interstitial pneumonia (UIP) </strong>refers to a morphological pattern of <a href="/articles/interstitial-lung-disease">interstitial lung disease</a>. In the past the term UIP was used synonymously with <a href="/articles/idiopathic-pulmonary-fibrosis">idiopathic pulmonary fibrosis</a> (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 <a href="/articles/non-specific-interstitial-pneumonia-1">non specific interstitial pneumonia (NSIP</a>) and <a href="/articles/desquamative-interstitial-pneumonia">desquamative interstitial pneumonia (DIP</a>) <sup>1</sup>.</p><h4>Pathology</h4><p>The histologic diagnosis of UIP is based on temporal and spacial heterogeneity, which is the identification of fibrotic lesions at different stages (fibroblastic infiltrates, mature fibrosis, and honeycombing) within the same biopsy specimen <sup>1</sup>. On a typical biopsy, there are areas of normal lung alternating with interstitial inflammation and honeycombing.</p><h5>Associations</h5><ul>
- +<li>connective tissue disorders<ul>
- +<li>
- +<a href="/articles/rheumatoid-arthritis">rheumatoid arthritis</a>: UIP is considered to be the dominant pattern in those with rheumatoid arthritis who have concurrent interstitial lung disease <sup>3</sup>
- +</li>
- +<li>
- +<a href="/articles/scleroderma">systemic sclerosis (scleroderma)</a>: can have either a UIP or NSIP (commoner) pattern <sup>4</sup>
- +</li>
- +<li>
- +<a href="/articles/polymyositis">polymyositis</a>/<a href="/articles/dermatomyositis">dermatomyositis</a>: those with these can have a UIP, NSIP or COP pattern <sup>4</sup>
- +</li>
- +<li>
- +<a href="/articles/mixed-connective-tissue-disease">mixed connective tissue disease</a>: can have either a UIP or NSIP pattern <sup>4</sup>
- +</li>
- +</ul>
- +</li>
- +<li>asbestos related interstitial lung disease: <a href="/articles/asbestosis">asbestosis</a> <sup>1</sup>
- +</li>
- +<li><a href="/articles/chronic-hypersensitivity-pneumonitis">chronic hypersensitivity pneumonitis</a></li>
- +<li>radiation</li>
- +<li>drug toxicity</li>
- +</ul><h5>Location: distribution</h5><p>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.</p><h4>Radiographic features</h4><h5>Plain film: chest radiograph</h5><p>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 subpleural reticular opacities that increase from the apex to the bases of the lungs. usually due to more extensive involvement of the lower lobes, the major fissure is shifted inferiorly; this is best seen on the lateral chest radiograph.</p><h5>HRCT </h5><p>When describing imaging features, the term <strong>UIP type pattern</strong> is often used. </p><p>The positive predictive value of CT in the diagnosis of UIP is high and ranges from 70-100% <sup>1</sup>.</p><p>As observed on a pathology specimen, cross sectional imaging also reveals heterogeneity, with patchy areas of fibrosis alternating with areas of normal lung <sup>5</sup>.</p><p>Typical features include <sup>1,5</sup>:</p><ul>
- +<li>the presence of <a href="/articles/reticular-opacities">reticular opacities</a> in the immediate subpleural lung, often associated with <a href="/articles/honeycombing">honeycombing</a> and/ or <a href="/articles/traction-bronchiectasis">traction bronchiectasis</a>, with peripheral and lower lobe predominance is considered a very good differentiating feature from patients with NSIP and concurrent emphysema <sup>6</sup>
- +</li>
- +<li>
- +<a href="/articles/ground-glass-opacification">ground-glass opacities</a>: usually less extensive than the reticular pattern and almost never seen in isolation - usually happens in areas of reticulation or honeycombing</li>
- +<li>
- +<a href="/articles/lung-architectural-distortion">lung architectural distortion</a>: which reflects lung fibrosis and is often prominent</li>
- +<li>lobar volume loss is seen in cases of more advanced fibrosis</li>
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