Glossary of Weissleder

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What are causes of lobar pneumonia?

What does lobar pneumonia affect?
Primarily alveoli
Why are there air bronchograms?
Because bronchi are not primarily affected, as alveoli are.
Why is there no volume loss?
Because airways remain patent
What are causes of bronchopneumonia?

What does it primarily affect?
Bronchi, with involvement of adjacent alveoli
What does this result in?

Pulmonary fibrosis
What are infectious causes of pulmonary nodules?
1) Fungal

2) Bacterial

3) Septic emboli
What is appearance of infectious nodules?
Variable size

Indistinct margins
What may nodules do?
What causes pneumatocele formation?
Air leak into the pulmonary interstitium
What organism is famous for pneumatoceles?
What organisms are famous for cavitary abscesses?
Anaerobes (i.e. klebsiella)


What are appearances of diffuse lung opacities?

Nodular (miliary)
What causes reticulonodular pattern?
Peribronchovascular inflammation
What are causes of this?
Viral pneumonia

What is another pathogen that causes diffuse lung opacities?
What is PCP pattern of involvement?
Primarily interstitial, with alveolar involvement later on.
What is the extreme of the interstitial involvement?
Upper lobe cystic changes, with resultant pneumothorax.
What percent get PTX?
What else is result of involvement of interstitium?
They can also get bronchpleural fistulae
What is the pattern of alveolar involvement in PCP?
Scattered involvement
What does this result in on imaging?
Ground glass on HRCT. Also see cysts due to interstitial involvement.
What is distribution on CXR?
Diffuse or perihilar.
What is initial CXR appearance of PCP?
Bilateral symmetric interstial pattern
What is later pattern?
Add in different degrees of alveolar consolidation
What can an organized effusion or empyema do?
Erode into chest wall or lung
When should pneumonia resolve by?
4 weeks
In what patients can you give up to 8 weeks?
Diabetics and older patients
What is differential for nonclearance?
Abx resistance or wrong pathogen

Recurrent infection

Underlying neoplasm
What patients get pseudomonas pneeumonia?
Ventilated patients

What are presentations?
There are 3:

1) Extensive bilateral consolidation, lower lobe predominant

2) Abscess formation

3) Nodular disease (rare)
What is another bacteria with lower lobe predilection?
What is the most common atypical pneumonia?
What is appearance?
Intracavitary mass.
In what percent is there alveolar consolidation?
What is the first stage of primary Tb?
1-7 cm focus of lung consolidation
Where does it occur?
Anywhere. Lower lobe is more common (60%) than upper lobe (40%) probably just because there is more lung and bloodflow in lower lobes
What is the next stage in primary Tb?
The consolidation undergoes caseous necrosis.
What occurs next?
Lesion calcifies
What also always occurs in primary Tb?
Where is lymphadenopathy?
Hilar and paratracheal
What percent of primary Tb gets pleural effusion?
What are potential complications of primary Tb?
Hematogenous spread from the area of consolidation, resulting in miliary Tb, which can go all over the body.

Cavitation of the area of consilidation, with erosion into bronchus, and transbronchial spread to rest of lungs.
What is commonly the only finding in primary Tb?
Adenopathy. The Ghon focus is not visible always.
What is this called in kids?
What populations get complicated primary Tb?

What causes secondary Tb infection?
Where does reactivation occur?
Apical and posterior segments of upper lobes

Superior segment of lower lobe
What occurs in anterior segment upper lobe?
Histo commonly does. Tb does not.
What is appearance of Tb?
Airspace disease, patchy or confluent.

May see linear densities radiating to hilum
What is common in secondary Tb?
In what percent?
What is rare in secondary Tb that is common in primary Tb?
What other space can secondary Tb involve?
What occurs?
Miliary Tb, which can seed other end organs
What is empyema that invades chest wall called?
Empyema necessatatis
What is Tb vascular invasion with aneurysm formation called?
Rasmussen aneurysm
What other way can Tb spread?
What is most common complication of parenchymal disease?
Lung fibrosis, which can be severe with cicatricial changes
What are other complications of parenchymal Tb involvement?
Bronchial invasion

Rasmussen aneurysm

Spread to GI tract via swallowed secretions
what is acute complication of bronchial invasion?
Transbronchial spread to other parts of lung(s)
What are late complications of bronchial involvement?

Bronchial stenosis

(opposite seeming lesions, but both caused by inflammatory process)
Differentiate primary and secondary Tb by location.
Primary more often lung bases

Secondary in upper lobes and superior seg LLs
Differentiate primary and secondary Tb by appearance
Primary is focal

Secondary is Patchy
Where is effusion more common, Primary or secondary Tb?
What is different about mycobacteria avium intracellulare infection versus Tb?
No primary/secondary crap. All infection is primary.
What patient populations get MAI?

Elderly people with COPD

Elderly women in good health
What may MAI be indistinguishable from on imaging?
What features suggest MAI over TB?
Bronchiectasis and Bronchial wall thickening
What percent of patients with TB vs. MAI have bronchiectasis?
30% in TB; almost 100% in MAI.

Similar values for bronchial wall thickening
What findings suggest TB over MAI?
1) Calcified granuloma (rare in MAI)

2) Septal thickening (common in MAI)
What types of patients get nocardia pneumonia?
Immunocompromised in some way
What patients are most susceptible
1) Lymphoma patients

2) Steroid therapy patients, especially those who underwent transplant.

3) Pulmonary alveolar proteinosis.
What is appearance of Nocardia?
Focal consolidaton is most comon
What are other appearances?
Irregular nodules

What are causes of actinomyces pneumonia?
Aspiration (lives in sputum of people with poor dentition)

Direct penetration into thorax
What feature is highly suspicious for actinomyces?
Pleural thickening with invasion of chest wall
What is not present?
What organism class causes pulmonary abscess?
Anaerobic bacteria
What are the varieties of pulmonary infection caused by anaerobes?
1) Abscess

2) Necrotizing pneumonia

3) Empyema
What defines abscess?
Cavity(ies) greater than 2 cm, usually with fluid level
What defines necrotizing pneumonia?
Similar pathology as abscess, but a more diffuse process, with cavities under 2 cm.
What predisposes to anaerobic infection?


Bronchial disease
What defines bronchial disease
Functional bronchial obstruction
What are examples of this?
Actual bronchial occlusion, i.e. from mass lesion

Bronchiectasis, resulting in functional bronchial obstruction
What are manifestations of viral pneumonia?
1) Acute interstitial pneumonia

2) Lobular inflammatory reaction

3) Hemorrhagic pulmonary edema
What is appearance of acute interstitial edema?
Thickening of peribronchovascular tissues

Thickening of interlobular septae
What is the distribution of acute interstitial pneumonia?
Diffuse or patchy
What is appearance of lobular inflammatory reaction?
5 mm nodules forming within secondary pulmonary lobules
What virus causes a special variety of this appearance?
What is special about varicells's nodular appearance?
Late calcification of nodules
What is appearance of hemorrhagic pulmonary edema?
Mimics lobar pneumonia
What is uncommon in viral pneumonia?
What is a potential sequela of viral pneumonia?
Chronic interstial fibrosis
What is this called?
Bronchiolitis obliterans
What percent of patients who get varicella develop pneumonia?
What is true of almost all of these patients?
Over age 20, so normal little kiddies with chicken pox are unlikely to get pneumonia. This also is a reason why they say chicken pox is so much worse in adults than children.
What is the progression of findings in varicella pneumonia? First stage:
Formation of numerous 5mm acinar nodules
What is next stage?
Healing, resulting in 1-2 mm calcifications throughout lungs.
In whom does CMV pneumonia occur?

What other feature is sometimes present in CMV?
What are the two broad categories of pulmonary fungal infection?
Endemic human mycoses

Opportunistic mycoses
What are endemic mycoses?
The infections limited to certain geographic regions
What are these?


Where are opportunistic mycoses located?
In what population do they occur primarily?
What are the opportunistic mycoses?



What opportunistic mycoses can also occur in immunocompetent hosts?

What are the phases in fungal pulmonary infection?
1) Acute phase

2) Reparative phase

3) Chronic phase
What additional phase can occur in immunocompromised patients only?
Disseminated disease
What is appearance of acute phase?
1) Segmental or nonsegmental confluent opacity


2) Patchy opacities
What can this appearance look like in immunocompromised person?
Miliary pattern
What is this due to?
Hematogenous dissemination
What is the appearance in the reparative phase?
Nodular lesions
What is a classic appearance of these nodules?
May cavitate
When they cavitate, what is the radiographic appearance?
Crescent sign
What is appearance of chronic phase?
Calcified lymph node or lung focus
What are the symptoms of histoplasmosis?
Usually none
What is appearance early in histo infection?
Parenchymal consolidation with adenopathy
What happens when histo heals?
Adenopathy heavily calcifies
What is appearance of histo when it goes into chronic infection mode?
What is appearance of histoplasmoma?
Solitary, sharply demarcated nodule
Where is histoplasmoma usually?
Lower lobes
What is another manifestation of chronic histo?
Fibrocavitary disease of upper lobes
What is this appearance the same as?
Post-primary TB
What is another appearance of chronic histo?
Cavitary nodules
What is appearance of disseminated histo?
Miliary lung nodules
What else is seen as a sequela of disseminated histo?
Calcifications in liver and spleen
What is sometimes a sequela of pulmonary histoplasmosis?
Mediastinal histoplasmosis
What are the two entities that can occur due to mediastinal histo?
1) Mediastinal granuloma

2) Mediastinal fibrosis
What is mediastinal granuloma?
Nothing. Just calcified mediastinal lymph nodes. But heavy mediastinal calcification is different than TB, however.
What is mediastinal fibrosis?
Diffuse infiltration of mediastinum with multiple densely calcified nodes and fibrotic change.
What are effects?
Constrictive pericarditis

SVC syndrome

Pulmonary artery occlusion

Airway compression
What are symptoms of coccidiomycosis lung infection?
Usually asymptomatic
What is appearance in the acute phase?
"Fleeting" consolidation
What part of lungs involved?
Lower lobes
What is another manifestation sometimes seen?
Adenopathy (20%)
What is appearance of coccy in the reparative phase?
Doesn't really have one, goes into chronic phase in some patients.
What percent of patients go into chronic coccy infection?
What is the appearance of chronic coccy?
What is characteristic of the nodules?
Not much
What percent cavitate?
When nodule cavitates, what suggests coccy?
Thin wall
What percent of cavitating nodules have thin wall?
What does the other 50% that have thick wall suggest?
What can patients who progress to the chronic form of coccy present with?
PTX, if their nodules cavitate and a bronchopleural connection is created
What percent of coccy nodules calcify?
What is characteristic of the disseminated form of coccy?
Nothing. Miliary nodules
What is appearance of blastomycosis?

Air space disease, more common than nodular disease (15% cavitate, like chronic coccy), more common than miliary disease
What is one manifestation of blasto that is somewhat suggestive?
Paramediastinal infiltrate with an air bronchogram
When there is nodular disease, what is commonly associated with it?
Satellite lesions around the nodule
What is very uncommon in blasto?


Pleural effusion
What is involved in 25% of cases of blasto?
How many varieties of aspergillosis are there?
What is each variety paired with?
A specific immune status
What are the immune statuses?


Mild immunosuppression

Severe immunosuppression
What is the variety of aspergillosis associated with hypersensitive immune response?
Allergic bronchopulmonary aspergillosis
What is the variety of aspergillosis assd with normal immune response?
What other variety can occur in normal host?
Semiinvasive form, if person is exposed to a large load of inhaled aspergillus.
What is variety associated with mild immunosuppression?
What is variety associated with severe immunosuppression?
What is ABPA?
Type I hypersensitivity reaction to aspergillus
What patients does it occur in?
What proportion are asthmatics?
Almost all affected by ABPA are asthmatics
What other group is sometimes affected?
Cystic fibrosis
What occurs initially?
Bronchospasm and bronchial wall edema, just like their asthma causes
What occurs in late stage ABPA?
Bronchial wall damage
What is treatment for ABPA?
Oral steroids
What is the most common radiographic finding?
Fleeting pulmonary opacities
What is the HALLMARK radiographic feature?
Central, upper lobe, saccular bronchiectasis with associated mucus plugging
What is this classic appearance called on CXR?
finger in glove
What is seen on CT?
Central upper lobe saccular bronchiectasis with mucus plugging and associated bronchial wall thickening
What occurs if ABPA is not appropriately treated?
Goes on to pulmonary fibrosis
Where does the fibrosis occur?
Mainly upper lobes, the same part involved with bronchiectasis
What is another feature sometimes associated with ABPA?
Cavitation in 10% of cases
What is required for aspergilloma to occur?
Preexisting lung cavity or bulla
What lesions typically cause such cavities?

End stage sarcoid
What about bullae?
Where do most fungus balls occur?
Upper lobes
What is treatment for fungus ball?
Surgical resection of fungus ball and intracavitary amphotericin
What may be seen specific to aspergilloma?
Lucent ring surrounding the ball
What can this be confused with?
Air-crescent sign of invasive aspergillosis.
How do you differentiate the two?
1) Clinical history (i.e. patient immunocompromised? Very sick?)

2) Air crescent doesn't go all the way around like air around a fungus ball does
What is seen around aspergilloma cavity?
Small rind of consolidation
What else is seen?
Adjacent pleural thickening
What is HALLMARK of aspergilloma?
Fungus ball moves with positional changes
What is progression of invasive aspergillosis?
Starts with endobronchial fungal proliferation.
What does this lead to?
Vascular invasion with thrombosis and infarction of lung
What is this type of infection called?
When invasion of vessels occurs, what happens?
Hematogenous spread
To where?



GI tract
What is characteristic initial radiographic feature of invasive aspergillosis?
Multiple pulmonary nodules
On CT, what is the characteristic associated feature of the nodules that is seen?
Halo of ground glass
What does this represent?
Pulmonary hemorrhage
What is the characteristic change in the lesion that occurs?
When do the lesions cavitate by?
2 weeks
What is the characteristic finding in invasive aspergillosis that signifies reparative phase?
Air crescent sign
Is the sign specific to aspergillosis?
What is the DDx for air crescent sign?

Septic emboli



What are the nonspecific findings also seen in invasive aspergillosis?
Focal consolidations

Peribronchial opacity
What is prognosis of invasive aspergillosis
Very poor. 70% to 90% mortality
What is treatment?
Amphotericin, systemic and intracavitary
Who is at risk for semi-invasive aspergillosis?
Diabetics, alchoholics, COPDers, malnourished, pneumoconiotics.
What is difference between this and regular invasive form?
Progresses more slowly (doesn't cavitate until 6 months, versus 2 weeks!)

Lower mortality (30%)
What is imaging appearance?
Same as invasive, just slower progression
Where is cryptococcus primarily endemic?
Not endemic to one region. Found everywhere.
Who gets infected with crypto?

Lymphoma patients


Steroid therapy
What are the 3 most common appearances of crypto lung disease?
Pulmonary mass

Multiple nodules

Lobar or segmental consolidation
What does not occur in crypto?


What patients get candidal pneumonia?
Lymphoma/leukemia patients

Bone marrow transplant patients
What are plain film findings?
Nonspecific opacities, usually lower lobe.
What is appearance of mucormycosis?
Similar to invasive aspergillosis, because also angioinvasive
What are characteristics of AIDS?
1) Lymphadenopathy (Think of CT of axilla with Gordon)

2) Opportunistic infections

3) Tumors
What are the infections associated with AIDS: Most common?
What percent of AIDS related opportunistic infection does PCP represent?
What CD4 count is needed to get PCP?
What percent of AIDS related infx is mycobacterial infx (TB, MAI)?
What CD4 count is needed for MAI?
What percent of AIDS related infx are bacterial pneumonia?
What are other AIDS defining infections?
Fungal infx (5%)

Nocardia (5%)
What tumors do AIDS patients get?
Kaposi Sarcoma

What can not exclude PCP?
A normal CXR
What does CMV infection do to AIDS patients?
Nothing much, just high titers
When is CT indicated in AIDS patient?
1) Symptomatic patient with normal CXR

2) Confusing CXR

3) Work up of focal opacities, adenopathy, or nodules
What is top 3 DDx for lung nodules in AIDS patient?
Septic infarcts/necrotizing pneumonia

Kaposi Sarcoma

Fungal disease
What defines septic infarcts?
Rapid increase in size
What fungal diseases present with nodular pattern in AIDS?

What is top 3 DDx of large opacity in AIDS?
1) Pneumonia (incl TB)

2) Non-Hodgkins pneumonia

3) Hemorrhage
What is top 3 DDx of linear interstitial opacities in AIDS?
1) PCP

2) Atypical mycobacteria

3) Kaposi
Top 3 for lymphadenopathy in AIDS?
AIDS itself can probaby do it.

1) Mycobacterial

2) Kaposi

3) Lymphoma
Top 3 for pleural effusion?
1) Kaposi

2) Mycobacterial or fungal

3) Pyogenic empyema
What percent of PCP has normal CXR?
What is appearance of PCP on HRCT?
Ground glass opacity with cystic changes
What does MAI usually cause?
Extrathoracic disease
What is most salient difference in appearance of TB in AIDS versus immunocompetent?
Prominent mediastinal adenopathy
What is DDx for mediastinal lymphadenopathy in AIDS?
Mycobacterial (TB, MAI)


How do you differentiate infection from tumor in AIDS patients on CT?
MAI and TB have low attenuation centers, and only exhibit rim enhancement.

Adenopathy in lymphoma enhances uniformly, unless treated.

KS enhances uniformly.
What is another finding more common in AIDS related TB?
Pleural effusion
What is appearance o/w?
Same as regular, with upper lobe consolidations and cavitations.
What percent of AIDS patients get fungal infection?
Less than 5%, so quite uncommon
What is the most common systemic fungal infection in AIDS?
What organ system does cryptococcosis usually involve in AIDS patients?
What percent of crypto patients have CNS involvement?

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