The Common Vein

• The reticular pattern,
  • characterized by a network of linear opacities
  • reflects the presence of fibrotic changes in  connective tissue structures including
    • the interlobular septa
    • intralobular tissues
      • bronchovascular bundle
      • interalveolar septa
• . The specific combination of involvement in these structures can provide additional clues to the underlying cause of the fibrotic lung disease.

The secondary pulmonary lobule is a functional unit of the lung that is typically defined by the structures supplied by a single small bronchiole. In fibrotic lung diseases with a reticular pattern on imaging, the involvement is often related to changes in specific structures within the secondary lobule. The primary structures affected include:

• Interlobular Septa:
  • Involvement in Reticular Disease:
    • Fibrosis or scarring of the interlobular septa can lead to
    • thickening  which can be irregular and incomplete
    • increased opacity,
  • Peribronchovascular Interstitium
    • Fibrosis in the peribronchovascular interstitium can lead to a reticular pattern,
    • especially if it affects the connective tissue around small bronchioles.
• Subpleural Connective Tissue:
  • Involvement in Reticular Disease: Fibrosis in the subpleural connective tissue
• Intralobular Septa:
  • Involvement in Reticular Disease: Fibrosis of the intralobular septa can also contribute to the reticular pattern.

 

 

• Subpleural reticulation
  •  typically in a peripheral subpleural distribution
  • located ?1 cm from the pleura
    • normal aging
      • can be accompanied by subpleural cysts,
      • independent of smoking history
    • UIP
      •  bilateral basilar subpleural reticulation,
      • traction bronchiectasis,
      • architectural distortion and
      • honeycombing
• UIP reticulation

  

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

  

  

  

  

  

  

  

  

   

  Reticular Changes Caused by Fibrosis of the Interlobular Septa

Combined Pulmonary Fibrosis and Emphysema

• Post COVID 19

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• Diffuse Reticular Lung Disease
  • PCP HIV

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    Reticular Changes Post XRT 

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