• is
    • inflammation and/or fibrosis involving (
      •  airways smaller than 2 mm in diameter, and/or
      • the alveolar ducts
  • pathology
    • cellular –
      • inflammatory cells
    • constrictive
      • fibrosis
        • submucosa and or
        • adventitia
  • imaging
    • CXR
      • ill-defined opacities
    • CT scan
      • centrilobular nodules with or without
      • air trapping
  •  Types
    • cellular
      • primary bronchiolar disease
        • acute bronchiolitis
          • usually viral infections,
            • infants and children
        • respiratory bronchiolitis,
          • smoking adults
        • follicular bronchiolitis,
          • connective tissue disease,
          • immunodeficiency disorders, or
          • chronic infections.
        • diffuse panbronchiolitis,
          • Asian population (particularly in the Japanese).
        • diffuse aspiration bronchiolitis,
        • mineral dust airway disease
          • inorganic dusts, – occupation-related
            • silica,
            • silicates,
            • asbestos,
            • iron oxide,
            • aluminum oxide,
            • talc,
            • mica, and
            • coal. The disorder is primarily
      • constrictive or obliterative bronchiolitis
          • bronchiolitis obliterans syndrome
            • bone marrow transplant
            • lung transplant
            • collagen diseases
            • inhalational diseases
            • autoimmunity
          • CT air trapping mosaic attenuation
  • related to ILD
    •  smoking related
      • respiratory bronchiolitis-associated interstitial lung disease (RB-ILD),
      • desquamative interstitial pneumonia (DIP),
    • hypersensitivity pneumonitis (HP),
    • cryptogenic or secondary organizing pneumonia (OP),
    • sarcoidosis, and
    • idiopathic pulmonary fibrosis (IPF).
Typical example of high-resolution computed tomography (HRCT) findings in desquamative interstitial pneumonia (DIP). Coronal a) and axial b) computed tomography (CT) slices show bilateral basal and peripheral ground-glass opacity. Some superimposed fine linear opacities are also seen, especially on the left side (coronal slice a)), corresponding with thickened inter- and intralobular septa.
Hellemons M etal Eur Respir Rev 2020; 29: 190181. – September 30, 2020

Progression of DIP and pulmonary fibrosis in a 55-year-old male smoker. (A) Axial CT image through the lower lobes from 2012 shows lower lobe predominant ground glass opacity with scattered cystic changes. In addition, there is mild reticulation (black arrows) and bronchiectasis (white arrows), signifying underlying fibrosis. Open lung biopsy showed DIP and a NSIP of fibrosis. (B) Axial CT image from 2015 at the same level as the scan obtained in 2013 shows progressive fibrosis with worsening reticulation (black arrows) and bronchiectasis (white arrows). Explant showed DIP combined with severely fibrotic NSIP.
Kligerman S et al Clinical-Radiologic-Pathologic Correlation of Smoking-Related Diffuse Parenchymal Lung Disease 2016
  • hypersensitivity pneumonitis (HP)
  • Head cheese or brawn is a cold cut terrine or meat jelly, often made with flesh from the head of a calf or pig (less commonly a sheep or cow), typically set in aspic, that originated in Europe. Usually eaten cold, at room temperature, or in a sandwich, the dish is, despite the name, not a dairy cheese. The parts of the head used in the dish vary, though commonly do not include the brain, eyes or ears of the animal. The tongue, and sometimes the feet and heart of the animal may be included; the dish is also made using trimmings from more commonly eaten cuts of pork and veal, with the addition of gelatin as a binding agent. Head cheese may also be made without using the flesh from the head of an animal.
    Courtesy Rainer Zenz source Wiki
  • Hypersensitivity Pneumonitis
    High-resolution CT: increase in density in areas of ground glass and air trapping in lower lobes in patients with hypersensitivity pneumonitis
    Courtesy Mluisamtz11

Links and References

Ryu, J Pulmonary Medicine Bronchiolitis Pulmonology Advisor

Winningham P, J. et al   Bronchiolitis: A Practical Approach for the General Radiologist RadioGraphicsVol. 37, No. 3 2017