Chapter 22 - Lungs Flashcards
What are the four principal components of the lungs?
Large airways (bronchi)
Small airways & air spaces (bronchioles & alveoli)
Interstitium
Vessels
Describe the morphologic appearance of bronchi.
Ciliated or columnar epithelium with goblet cells. Goblet cell metaplasia can indicate irritation, as can squamous cell metaplasia.
Also note seromucinous glands, cartilage, smooth muscle, and bronchial arteries.
Describe the morphologic appearance of bronchioles.
Cuboidal epithelium without goblet cells.
Clara cells, which are difficult to see.
No cartilage.
Describe the morphologic appearance of alveoli.
Thin walls lined by flat type I epithelium. Alveolar macrophages scattered throughout.
Cuboidal epithelium indicates type II hyperplasia, seen in inflammation/repair.
Describe the morphologic appearance of vessels
Pulmonary arterioles: Run with bronchioles, two elastic layers on Movats stain.
Veins: Run in interlobular septa, one irregular elastic lamina.
Lymphatics: Run with arteries, veins, and in pleura.
What is Movats stain, and what does it paint?
A supplemental stain for fibrotic lung.
Elastic laminae - Black
Hyaluronic acid - Aqua blue
Mature collagen - Yellow
Smooth muscle - Dull red
Fibrinoid necrosis - Bright red
What are the three phases of injury response in lung?
Acute, subacute, chronic
How does acute lung injury manifest?
What is acute interstitial pneumonitis, and how does it appear?
As diffuse alveolar damage.
AIP has no identifiable factor. It features interstitial edema/hemorrhage, hyaline membrane formation, type II hyperplasia, and fibrin thrombi.
How does subacute lung injury manifest?
Fibroblast foci form in alveoli and bronchioles. This is indistinguishable from BOOP.
How does chronic lung injury manifest?
With end fibrosis and honeycomb lung. “Usual interstitial pneumonia” is the nonspecific pattern, and is called “idiopathic pulmonary fibrosis” when no etiology is known.
Describe the appearance of usual interstitial pneumonia.
Temporal heterogeneity; meaning seeing acute / subacute / chronic injury in the same tissue.
Prominent interstitial fibrosis, distortion of airspaces, with fibroblast foci, acute & chronic inflammation.
What are the two forms of allergic lung disease, and what are some examples?
IgE-mediated: Asthma, ABPD, eosinophilic pneumonias
Cell-mediated hypersensitivity: Pneumonconioses, patchy chronic interstitial pneumonia, foci of BOOP.
What lung disease patterns are seen in smokers?
DIP (desquamative interstitial pneumonitis)
Respiratory bronchiolitis
Langerhans cell histiocytosis
Usual interstitial pneumonia
Obstructive lung diseases: Emphysema and chronic bronchitis
What is DIP?
Desquamative interstitial pneumonitis
Alveolar macrophages pack the alveoli, usually in smokers but in other disease processes as well.
How does langerhans cell histiocytosis appear?
Why is this in the lung chapter?
Collections of histiocytes (pale nuclei with folds and creases), sometimes with eosinophils (“eosinophilic granuloma”).
Half of cases occur in adults, generally as isolated pulmonary diseases of smokers.
What two epithelia do lung cancers arise from?
Respiratory epithelium
Squamous metaplastic epithelium
What is atypical adenomatoid hyperplasia, and how does it appear?
A small focus (~1cm) of type II hyperplasia, which is plump cuboidal to columnar eosinophilic. This is probably a dysplastic lesion and results from chronic irritation.