Fibrotic Hypersensitivity Pneumonitis (HP)

Fibrotic HP

 

Upper lobe predominance

  • reticulation,
  • raction bronchiectasis and
  • lume loss,
  • with or without evidence of honeycombing,  [,]. Patients
  • often an
    • upper lobe predominant distribution of fibrosis,
    • but diffuse and lower lobe predominant changes also.
    • bronchocentricity to the fibrosis can be observed at the lung apices.
    • reticulation in fibrotic HP i
      • predominantly subpleural or
      • peri-bronchovascular distribution.
Fibrotic Hypersensitivity pneumonitis

Normal Small Airways 

The Acinus,
The Duct, and the Artery
The pulmonary arteriole accompanies the airway as it carries oxygen from the trachea to the alveoli. They part ways at the alveoli where the pulmonary venule then takes the oxygenated blood from capillary network around the alveoli back to the left atrium.
The intimate relationship of the airways and the pulmonary artery and their close approximation in size, is helpful in radiology, firstly to identify theese structures and secondly to define disease such as heart failure and bronchiectasis.
The acinus as shown in this image is defined as a unit of lung consisting of a single first order respiratory bronchiole that subtending a cluster of alveoli reminiscent of a bunch of grapes or berries (acinus in Latin means berry) .  The lobular bronchiole (lb) branches into the terminal bronchiole (tb), which then branches into the first order respiratory bronchiole (rb).  Subsequent branching  after the respiratory bronchiole,  includes in order, the  alveolar duct (ad), alveolar sac (as), and then finally the berry like alveoli.
Courtesy Ashley Davidoff 2019
lungs-0033-low res
Respiratory Bronchioles
This slide shows the transition from a terminal bronchiole, with a low cuboidal epithelium, to respiratory bronchioles, with a squamous epithelium. Terminal bronchioles are last generation of conducting airways.
Respiratory bronchioles can be identified by the presence of some alveoli along their walls. The respiratory bronchiole splits into a number of alveolar ducts, which terminate in alveolar sacs and individual alveoli
Courtesy medcell.med.Yale.edu

 

The Alveolus –
The Buck Ends Here
The alveolus is lined by a simple epithelium – one cell layer thick. There are two types of lining cells; Type 1 pneumocytes are squamous cells that cover 90% of the surface of the inner lining of the lung , and type II cuboidal pneumocytes that are in fact much more numerous than Type I. They are involved in the production of surfactant . In the lumen there are resident macrophages which play a crucial role in the immune system. The mucosa is grounded by a basement membrane and a lamina propria, and connected to the lamina propria and basement membrane of the surrounding capillary. The alveolus is lined by a thin layer of surfactant. (teal blue)
Ashley Davidoff
TheCommonVein.net
Magnification of Normal Histology of the Lung
Lower magnification of the lung with H and E stain shows cup-shaped alveolar spaces outlined by delicate thin alveolar capillary membrane.
key words
lung, pulmonary, normal alveolus, alveoli, histology, interstitium, interstitial
Courtesy Armando Fraire MD. 32819

Small Airway Disease Terminal Bronchiole

Non-specific severe chronic inflammation of a terminal bronchiole.
Courtesy Dr Yale Rosen

Small Airway Disease  Giant Cell Around the Terminal Bronchiole

Hypersensitivity pneumonitis
Multinucleate giant cells within a terminal bronchiole.
Courtesy Dr Yale Rosen

Small Airway Disease – Organizing Pneumonia – Terminal Bronchiole

Hypersensitivity pneumonitis-organizing pneumonia Case 129
Areas of organizing pneumonia are frequently seen in hypersensitivity pneumonitis.
Courtesy Dr Yale Rosen

Interstitial Infiltrates

Hypersensitivity pneumonitis
Mild interstital inflammation and multiple granulomas.
Courtesy Dr Yale Rosen
Hypersensitivity pneumonitis
Interstitial chronic inflammation and a granuloma composed of multinucleate giant cells.
Courtesy Dr Yale Rosen
Hypersensitivity pneumonitis
Mild interstital inflammation and multiple granulomas.
Courtesy Dr Yale Rosen
Hypersensitivity pneumonitis
An interstitial granuloma composed of multinucleate giant cells.
Courtesy Dr Yale Rosen
Hypersensitivity pneumonitis
Patchy chronic interstitial inflammation and a granuloma composed of multinucleate giant cells.
Courtesy Dr Yale Rosen

 

 

High magnification photomicrograph of a lung biopsy taken showing chronic hypersensitivity pneumonitis (H&E), showing mild expansion of the alveolar septa (interstitium) by lymphocytes.[clarification needed] A multinucleated giant cell, seen within the interstitium to the right of the picture halfway down, is an important clue to the correct diagnosis.
Courtesy Wikiwand
web lungs 435
Nutshell Buzz
Low magnification view of the histology of chronic hypersensitivity pneumonitis. The interstitium is expanded by a chronic inflammatory infiltrate. Two multinucleated giant cells can be seen within the interstitium at left, and a plug of organizing pneumonia at bottom left.
Courtesy Mutleysmith Wikipedia
High magnification micrograph of hypersensitivity pneumonitis showing granulomatous inflammation. Trichrome stain.
Courtesy Nephron