Lecture 13: Pathology of Airway Disease Flashcards
Asthma: definition
Episodic condition of airflow obstruction characterized by REVERSIBLE airway narrowing
Three types asthma
Extrinsic (Type 1 hypersensitivity); intrinsic (nonimmune: aspirin/cold/exercise); status asthmaticus (unremitting due to previously sensitized antigens)
Which asthma can be deadly?
Status asthmaticus
Asthma: gross (3)
Overdistended lungs, small areas of atelectasis, thick mucus plugs in proximal bronchi
Asthma: microscopic (6)
Mucus plugging, EOSINOPHILIC inflammation, increased mucosal goblet cells, THICKENED BASEMENT MEMBRANE, bronchial SM hypertrophy, airway wall edema
Do you see enlarged submucosal glands in asthma?
Somewhat
When you think asthma, what should you think is filling the airways?
MUCUS
COPD: diagnosis
History (chronic bronchitis), physical exam, gross pathology, PFTs + DLCO, ABG
DLCO is ________ in COPD and ________ in chronic bronchitis
Reduced; normal
Emphysema: definition
Permanent enlargement of the airspace distal to the terminal bronchiole due to destruction
Three kinds of emphysema
Centriacinar (smoking, 95%), panacinar, paraseptal
Which kinds of emphysema cause clinically significant airflow obstruction?
Centriacinar and panacinar
Centriacinar: define
Central/proximal parts of acini are affected, whereas distal alveoli are spared that typically involves upper lobes (smoke floats upward)
Centriacinar is often associated with…why?
Chronic bronchitis; smokers/coal miners
Panacinar: define
Acini are uniformly enlarged associated with alpha-1 antitrypsin deficiency
Paraspetal: define
Proximal portion of acinus is normal, but distal is involved (adjacent to pleura), can result in spontaneous pneumothorax
Alpha-1 antritrypsin deficiency: what does AAT do and where is it from?
AAT of liver provides 90% of elastase inhibition in plasma
Alpha-1 antritrypsin deficiency: normal allele and bad allele
“M” vs “Z”
Alpha-1 antritrypsin deficiency: presentation
Young emphysema and cirrhosis
How does AAT work?
Inhibits proteases (elastase) secreted by neutrophils –> if AAT is not there, you end up with too much elastase, which destroys lung tissue
How does smoking work?
You end with a functional AAT deficiency because free radicals, etc, inactivate antiproteases (like AAT) –> increase in neutrophil elastase –> tissue damage
How much lung is lost before you get symptoms?
1/3
Bullos emphysema: define
Any form of emphysema that forms very large air spaces (>2 cm) right under the pleura
What can bullos emphysema cause?
Pneumothorax and hemorrhage
Is chronic bronchitis more common in smokers? Pathology?
Yes (4-10x), tobacco interferes with ciliary action –> directly damages airway epithelium, inhibits WBC ability to clear bacteria, infections maintain the bronchitis
Chronic bronchitis: gross
Boggy mucosa with excessive mucinous secretions and pus (if infection)
Chronic bronchitis: histologically (early and late)
Early: hypersecretion of mucus in large airways w/ hypertrophy of submucosal glands; later: increase in goblet cells in small airways cause excessive mucus production and airway obstruction
At what stage in chronic bronchitis do you see an increased Reid index? What is the Reid index?
Later stages; ratio of thickness of mucus gland layer to wall b/t epithelium and cartilage
Does chronic bronchitis have eosinophil infiltrate?
Nope: more neutrophil and lymphocyte
Normal Reid index
0.4
Bronchiectasis: definition
IRREVERSIBLE dilatation of proximal bronchi due to destruction of bronchial wall
Two types of bronchiectasis
Localized (obstructive process) or diffuse (non-obstructive)
Bronchiectasis is not a disease itself, but a…
Pulmonary manifestation of some other disorder
Obstructive cause of localized bronchiectasis
Tumor, foreign body, inspissated mucus
Congenital cause of diffuse bronchiectasis
CF, immunodeficiency states, immotile cilia: Kartegeners syndrome
Infectious causes of bronchiectasis
Severe necrotizing pneumonia (staph, TB)
Pathogenesis of bronchiectasis: 3 main points
- Impaired clearance –> 2. Inflammation –> 3. PMNs and their cell products
Bronchiectasis: gross
Dilated, tortuous airways extending to pleura with mucus
Why is bronchiectasis obstructive?
Collapse of dilated airways on expiration
Why can bronchiectasis cause hemorrhage?
Airways pairs with pulmonary artery, can be eroded into
Bronchiolitis: definition
Inflammatory response to injury of small airways +/- fibrosis in a diffuse or nodular fashion
What is a small airway and epithelium
Internal diameter of less than 2 mm devoid of cartilage; simple columnar cells +/- cilia with little connective tissue, resting on SM cells
Function of small airways
Don’t contribute much but can harm lung function if damaged
Etiology of small airway disease
Primary: constrictive bronchiolitis; secondary: lots of other airway disease
Histological appearance of small airway disease
One restricted airway (for example, fibrotic) with nearby dilated airway and adjacent airspaces filled with foamy macrophages
Form of bronchiolitis that is more problematic. Two types?
Fibrotic; constrictive and intralumenal
Describe constrictive bronchiolitis
Primary disease of small airways; subepithelial collagen deposition (increased CT b/t epithelium and SM layers)
What do you see constrictive bronchiolitis with (main association)?
Chronic transplant rejection (abnormal healing response)
Late in the stage of constrictive bronchiolitis, what can you see histologically?
Airway lumen completely filled with scar due to OUTSIDE –> INSIDE CONSTRICTION
Describe intraluminal bronchiolitis (obliterans)
Organization of luminal inflammatory exudates; polypoid plugs of fibroblastic tissue; FILLING COMES FROM INSIDE –> OUTSIDE
What is intraluminal bronchiolitis associated with? What is it rarely?
Alveolar organizing pneumonia; rarely an isolated disease
