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Pathology - S2B1 - 4 Vascular and Infectious


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What could cause a vasospasm in the lungs?
amphetamines (cocaine)
What are Pulmonary Infarcts most commonly the result of?
Pulmonary Thromboembolism
75% of pulmonary infarcts invlove which part of the lungs?
Lower lobes b/c perfusion is greater than ventilation in the lower lobes
What is the most common origin of Pulmonary Thromboembolisms?
Femoral Vein = deep veins in legs
Macroscopically, what is the classic appearance of Pulmonary Infarcts?

Hemorrhagic infarct, which extends to the periphery of the lung as a wedge
What can happen if the hemorrhagic infart extends to the pleural surface?
can be covered by Fibrinous exudate and cause Pleural friction rub
When an infarct is caused by a septic embolus, a septic infarct may occur and evolve into what?
What is the classic triad associated with Pulmonary Embolism?
1. Dyspnea (shortness of breath)
2. Pleuritic chest pain
3. Hemoptysis

**most patients are extremely dyspneic**
List risk factors for pulmonary thromboembolism (6)
1. Cancer (Trousseau syndrome = pancreatic carcinoma cancer cells release thromboplastin)
2. Cardiac disease
3. Obesity
4. Prolonged bed rest
5. Acute paraplegia
6. oral contraceptive use
What is Homan's sign?
Use to check for Deep vein thrombosis --> pain in the calf is produced by passive dorsiflexion of the foot
What is the underlying principle of order of scanning in the V/Q scan?
-1st scan using isotope with smallest dose or lowest energy to avoid down-scatter of higher energy isotope
-scan with highest energy isotope last
When doing the V/Q scan, which imaging when done first can be cost effective?
Perfusion because if it is normal, a ventilation study is not needed to assess for pulmonary emboli
To determine the etiology of a perfusion defect, what 2 things are needed?
1. ventilation study

2. CXR
A V/Q mismatch suggest (V/Q is infinite)?
Pulmonary embolism
A V/Q match suggests?
parenchymal disease
What is the risk of performing an angiogram in trying to detect the presence of Pulmonary Thromboembolism?
the radiographic contrast itself can cause thrombosis
What are Interstitial Pneumonias usually caused by? (2)
1. viral infections

2. Mycoplasma pneumonia
Define Bronchopneumonia
-patchy consolidation centered around small bronchi
-PMN reaction
What is the cause of Bronchopneumonia?
inhalation/aspiration, mostly bacteria, some fungi
Define Lobar Pneumonia
-identical involvement of alveoli, same time and same extent
-intra-alveolar exudate resulting in consolidation
What is the most common cause of Lobar Pneumonia?
Strep pneumo

*Klebsiella also
List the 4 stages in Lobar Pneumonia
1. congestion
2. red hepatization
3. gray hepatization
4. resolution
Describe the Congestion phase of Lobar Pneumonia
- heavy, boggy, red lung = active hyperemia

- histologically = vascular engorgement, intra-alveolar fluid with few NO and often the presence of numerous bacteria
Describe the Red Hepatization phase of lobar pneumonia
- lobe is distinctly red, firm, and airless, with a liver-like consistency

- Histo = alveolar spaces are filled with RBC's, PMN's, and fibrin
Describe the Gray Hepatization phase of Lobar pneumonia
-grayish,brown dry surface

- Histo = disintegration of RBC's and the persistence of fibrinopurulent (Fibrin + Neutrophils) exudate within air spaces
Expected oropharyngeal flora in ~20% of adults
Strep pneumo
Normally sensitive to penicillin, but drug resistance is emerging
Strep pneumo
With this bacteria, African-Americans have a 3-5 fold higher incidence of bacteremia than whites and rates of invasive disease are also exceptionally high among Native Americans
Strep pneumo
What is the name of the vaccine available for adults against Strep pneumo?

What type of vaccine?

Polysaccharide vaccine that covers most of the bacteremic strains of pneumococcus
Name of Strep pneumo vaccine given to children?

Vaccine properties?

Heptavalent vaccine linked to Diphtheria toxin
Classically "lancet-shaped" gram + diplococcus with a capsule
Strep pneumo
What are most Gram - pneumonias due to?
Endogenous aspiration of oropharyngeal flora
Eponymic name is Friedlander's pneumonia
Encapsulated organism, 10% of all nosocomial pneumonias
Gram -, fat rod surrounded by a mucoid capsule
Most common gram - causing lobar pneumonia and typical pneumonia in elderly patients in nursing homes
Common cause of Pneumonia in Alcoholics
Pneumonia associated with blood-tinged, thick, mucoid sputum; lobar consolidation and abscess formation simulating TB
Intracelluar organism that requires anti-microbial drugs with good cytoplasmic penetration, such as Macrolides
Infection from inhalation of aerosol from contaminated stored water, most often in air-conditioning systems
Detected by Immunofluorescence of sputum
Inoculated on Charcoal Yeast extract plates
Stained with Dieterle silver stain
Gram - rod with green sputum (pyocyanin)
P. aeruginosa
Common colonizer of CF patients
P. aeruginosa
Pneumonia from this bacteria is often associated with infarction due to vessel invasion
P. aeruginosa
Mucoid colonies in chronically infected patients make eradication impossible
P. aeruginosa
Definition: a localized collection of pus in the lung resulting from liquefactive necrosis of lung tissue
Lung Abscess
List 4 bacteria that frequently cause abscesses
1. S. aureus ***
2. Pseudomonas
3. Klebsiella
4. Proteus
List 4 mechanisms that can lead to Lung Abscesses
1. aspiration of infected material, especially Gram - and anaerobes in patients with dental caries
2. Antecedent primary bacterial infection
3. Septic embolism
4. obstruction secondary to neoplasm
Definition: local aggregations of macrophages that become epithelioid cells
Granulomatous inflammation = granuloma
What are 3 causes of granulomatous inflammation in the lungs
1. Mycobateria

2. Dimorphic fungi

3. Sarcoidosis
What is the initial focus of Tuberculosis in primary infection?
Ghon Complex
What is a Ghon Complex?
1. Parenchymal subpleural lesion

2. enlarged hilar lymph nodes

*both contain tuberculous granulomas
Describe Miliary Tuberculosis
Secondary TB with the presence of multiple, small tuberculous granulomas in many organs, which result from the hematogenous spread of bacteria
Name 5 complications of TB
1. cavitation
2. hemorrhage
3. bronchopleural fistulas
4. Bronchopneumonia
5. Aspergillomas
With Tuberculosis, swallowed sputum may lead to ________
This complication of TB is particularly a problem in children and the immunosuppressed
TB meningitis
List 3 common causes of diffuse infiltrate in IC'ed hosts
Drug reaction
List 3 common causes of focal infiltrates in IC'ed hosts
Gram - rods
S. aureus
Fruiting body and narrow-angled, branching septate hyphae
Non-invasive "fungus ball", occupies a previously existing anatomical space, such as a sinus cavity or abscess cavity
Most common opportunistic infection in AIDS patients
Pneumocystis carinii
Replicates in the human lung, with a complicated life cycle that includes formation of intra-alveolar CYSTS
Pneumocystis carinii
Most of the population is infected by age 5 with this organism
What is PCP probably acquired from?
Aerosolized mouse or rat urine
What drug is given prophylactically for PCP when CD4 counts drop below 200
What do CXR's look like with PCP?
Patchy, pneumonia, with a characteristic "ground-glass" appearance
Budding yeast with narrow-based buds
Cryptococcus neoformans
Systemic fungi surrounded by a thick capsule
Is ubiquitous in the environment, preferring alkaline bird droppings as its habitat
Cryptococcus neoformans
Usually causes meningitis in IC'ed, but primary lung disease may occur
Cryptococcus neoformans
What test is useful in detecting Cryptococcus in normal hosts?
Antigen testing of the CSF
What test is adequate for detecting Cryptococcus in IC'ed host?
India Ink prep
Dimorphic large yeast with Broad-based budding
Blastomyces dermitidis

What is this showing?
Saddle embolus originating from the deep veins of the leg
-straddles right and left pulmonary artery = sudden death
Why are small Pulmonary Infarcts "Hemorrhagic" or "red" infarcts?
The lung has a dual blood supply
-Pulmonary Artery
-Bronchial arteries

What is this picture showing?
-pathy areas where PMN's are within tiny bronchioles

What are these microbes?
Strep pneumo

What is this showing?

What is the most likely cause?
Lower Lobe consolidation


What is this showing?
Lobar Pneumonia
-if the bronchi were filled with pus = Bronchopneumonia, but since they are spared it is Lobar

What is the likely cause of this? How do you know?
-consolidation + abscesses

This person contracted 5-lobe consolidation by working in the produce section with water mist sprayers

What microbe?
What are these 2 stains?

Dieterle Silver

What microbe?
What are these 2 stains?

Dieterle Silver

What are the 3 associations here?
1. P. aeruginosa
2. Cystic Fibrosis
3. Bronchiectasis

What organisms typically cause this?
1. S. aureus
2. Klebsiella
3. Aerobic and anaerobic streptococci
4. Gram - organisms
What is a Simon focus?
Granuloma at the lung apex in Secondary Pulmonary TB
-occurs at apex due to high O2 tension

What is this microbe?
When does Invasive (disseminated) Aspregillosis usually only occur?

What is this?

What is shown here?

What is this?
In culture, what do the hyphae look like?

Acute (<45 degrees) branching Septate Hyphae

This was from an Immunocompromised patient.
What pathogen?
Invasive Aspergillosis

What pathogen?
How do you know?
Invasive Aspergillosis

Acutely branching septate hyphae

What pathogen?
What does it usually cause?
How are you exposed to it?
-Cryptococcus neoformans = narrow-based budding
-Meningitis in IC'ed
-Pigeon excreta

What pathogen is this?
Who does it usually affect?
Pneumocystis carinii

IC'ed = AIDS

What is this showing?

How do you know?

Patchy areas of pulmonary consolidation

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