Pulmonary Infection Pathology Flashcards
A lot of this we saw back in micro... but that feels like a lifetime ago.
4 routes for pathogens to get to the lungs?
Inhalation.
Aspiration. (implies liquid from stomach/mouth)
Hematogenous.
Direct extension (corrected from inspection… too much ICM)
6 respiratory defenses that can be impaired / problems that can increase susceptibility to infection?
- Cough reflex.
- Mucociliary function.
- Phagocytosis / bacterial killing.
- Pulmonary edema.
- Altered secretion.
- Immunosuppression.
(Immunosuppression is perhaps the most obvious, but the infections people get from 1-5 illustrate their importance.)
You guys know what acute, chronic, and granulomatous inflammation look like.
Sure do.
What does alveolar damage from “atypical” pneumonia / ARDS look like on histology?
Alveolar destruction with hyaline membranes, which is made of debris from Type I & II epithelial cells + leaked capillary proteins.
A “typical” bacterial pneumonia can either have a lobar pattern or a…
lobular pattern (bronchopneumonia)
How do auscultation findings change when a pneumonia becomes “consolidated”?
When mucus in the alveoli dries out, sounds go from wet rales to “tubular breath sounds.”
4 classic stages of untreated lobar pneumonia?
Congestion (with edema, wet rales).
Red hepatization (lobe solidified with dense PMN infiltrate, RBCs, and fibrin, tubular breath sounds).
Grey hepatization (fibrin and macs present, RBCs and PMNs going away).
Resolution.
Grossly, and on CXR, bronchopneumonia appears more patchy.
Okay.
4 complications of bacterial pneumonia?
- Organization (i.e. scarring).
- Abscess.
- Empyema (pus in the pleural space).
- Hematogenous dissemination.
What are Masson bodies?
Markers of a prior, organized pneumonia.
Fibroblasts make a collagen plug that can fill alveoli /block airways.
What’s BOOP?
Bronchiolitis obliterans with organizing pneumonia.
Fibroblasts grow into the exudate of a bronchopneumonia… and gum things up.
2 clinical signs of lung abscess? (1 is by imaging)
On CXR, can see a mass with an air-fluid level.
Foul-smelling sputum.
3 ways that abscess can happen?
Aspiration.
Infection with virulent organism (eg. Staph, Kleb).
Bacteria post-obstruction. (if you see a smoker with a lung abscess, look for cancer).
Why might a abscess caused by aspiration be associated with hemorrhage?
Damage from gastric acid.
What kind of bugs will you see on a sputum gram stain in aspiration pneumonia?
A polymicrobial infection - lots of different things.
3 types of organisms that cause an “atypical” pneumonia?
Viruses
Mycoplasma
Chlamydia.
Where’s the inflammation happens in viral pneumonia?
Interstitial space.
General rule about the location of inclusions caused by DNA vs. RNA viruses?
DNA viruses - nuclear inclusions, usually (eg. CMV, Herpes)
RNA viruses - cytoplasmic inclusions, usually (eg. RSV, adeno)
Both can cause syncytia to form, though.