• UIP pattern:

 

• Starts peripheral
  • • subpleural
    • basal
    • reticular
    • traction bronchiectasis
  • honeycombing 70-80%
  • +/- bronchiectasis/bronchiolectasis
  • Structures Involved

70 year old male with UIP showing extensive dominantly bibasilar and peripheral reticulation

Interstitial Fibrosis

• • 

    

Progression of Disease

The Interstitial  Fibrotic Process Progresses – Resulting in Honey Comb Lung and May Involve the Small Airways as Well

Honey Comb Lung

The honeycomb change in usual interstitial pneumonia (UIP) is thought to be the end result of chronic interstitial inflammation and fibrosis.

In UIP, there is chronic inflammation and injury to the lung tissue, leading to the accumulation of scar tissue (fibrosis) and destruction of normal lung architecture. The honeycomb change refers to the presence of cystic airspaces lined by thickened fibrous tissue and surrounded by areas of dense fibrosis, resembling a honeycomb. These cystic airspaces are the result of progressive destruction of normal lung tissue and the replacement of the destroyed tissue by fibrosis.

The exact mechanism underlying the honeycomb change in UIP is not fully understood, but it is believed to be the result of a combination of factors, including:

1. Persistent lung injury: Chronic injury to the lung tissue leads to the accumulation of scar tissue and destruction of normal lung architecture.
2. Abnormal wound healing: Abnormal wound healing response to the chronic lung injury leads to the formation of dense fibrosis.
3. Altered surfactant metabolism: Altered metabolism of surfactant, which is a substance that helps to keep the air sacs in the lungs open, can lead to collapse of the air sacs and the formation of cystic airspaces.
4. Impaired regeneration: Impaired regeneration of lung tissue due to aging or other factors may also contribute to the development of honeycomb change in UIP.

In summary, the honeycomb change in UIP is the result of chronic interstitial inflammation and fibrosis, which leads to the destruction of normal lung tissue and the formation of cystic airspaces surrounded by areas of dense fibrosis.

Honeycomb lung is subpleural in location because the subpleural area is more susceptible to injury and fibrosis than other areas of the lung.

The subpleural area is the region just beneath the pleura, which is a thin membrane that lines the surface of the lungs and the inside of the chest wall. The subpleural area is the site where the alveoli (air sacs) are located and is involved in gas exchange between the lungs and the bloodstream.

In usual interstitial pneumonia (UIP), which is the most common cause of honeycomb lung, there is chronic inflammation and fibrosis of the lung tissue. The subpleural area is more exposed to environmental insults, such as inhaled irritants, viral infections, or autoimmune processes, that can lead to chronic inflammation and injury of the lung tissue. The subpleural area is also more susceptible to mechanical stress, such as the strain that occurs during breathing, which can contribute to the development of fibrosis.

Furthermore, the subpleural area is relatively poorly vascularized and has less supportive tissue than other areas of the lung, making it more prone to injury

 

Imaging in an 81F with End Stage UIP

Small Airway Disease

 

• While UIP is primarily a disease of the lung interstitium, it can also affect the airways to varying degrees.
• Small airway involvement in UIP can contribute to symptoms such as cough, wheezing, and shortness of breath.
• Small airway involvement can also be a predictor of more rapid disease progression and worse outcomes.
• Small airway involvement is also a feature of other interstitial lung diseases, such as nonspecific interstitial pneumonia (NSIP) and respiratory bronchiolitis-associated interstitial lung disease (RB-ILD).

Small Airway Fibrosis

Small Airway Fibrosis and Luminal Narrowing or Obstruction

UIP and Small Airway Disease on CT scan 

 

CT in the coronal projection from a patient with UIP (upper image) shows predominantly basilar  reticular disease with some extension to the upper lobes.  In the middle magnified images there is thickening of the wall of a few of the visualized bronchioles The lower magnified images show solid centrilobular nodules. No air trapping was identified

Ashley Davidoff MD TheCommonVein.net lungs-0778

 

 

• • UIP Patterns
  • small but prominent mediastinall nodes
    • Less common
      • ground glass
      • consolidation
      • lung cancer
      • pneumomediastinum
      • ptx

• 4 patterns
  • • UIP
      • basal peripheral reticulation traction and honeycombing

      • 

    • Probable
      • basal peripheral reticulation traction and NO honeycombing

        

    • Indeterminate
      • subtle reticulation
      • may be mid or upper lungs
      • no honeycombing

        

    • Alternate Diagnosis

      

• Honeycombing, with or without peripheral traction bronchiectasis or bronchiolectasis
• Often heterogenous distribution, being occasionally diffuse, and may be asymmetrical

 

 

…………………………………………………………………………………………..

UIP

Predominantly subpleural and basal

Traction bronchiectasis

Honeycombing

 

When cause is unknown it is called IPF ( idiopathic pulmonary fibrosis)

Causes collagen vascular disease connective tissue diseases (primarily rheumatoid arthritis), drug toxicity, chronic hypersensitivity pneumonitis, asbestosis and Hermansky–Pudlak syndrome.^[2]

 

UIP and CHF in a 70 year old male
Reticular Pattern Exemplified

Honeycombing has prognostic significsnce

with median survival 2.1 years

without  5.8years

Accelerated Deterioration in IPF

Lung Cancer in UIP 5-10%

• • INTERSTITIAL PNEUMONIA , IP
    • • Usual interstitial pneumonia (UIP)
      • Nonspecific interstitial pneumonia (NSIP)
      • Cryptogenic organizing pneumonia (COP)
      • Desquamative interstitial pneumonia (DIP)
      • Respiratory bronchiolitis-interstitial lung disease (RB-ILD)
      • Acute interstitial pneumonia (AIP)
      • Lymphoid interstitial pneumonia (LIP)
      • Idiopathic pleuroparenchymal fibroelastosis (PPFE)

References and Links

UIP Wiki

Links and References

• Videos 
  • AUR
    

    Title	web link
    Current Guidelines in the Dx of UIP and IPF	AUR Cardiothoracic Imaging

• TCV
• ILD Map
•  Cases
  • 033Lu Rapid Progression of UIP
  • 65Lu Honeycomb predominant ILD COP RA UIP

Videos