Thoracic 1 Flashcards
How can you differentiate the L and R ribs on a lateral chest X-ray?
Left ribs are smaller with sharper edges
Note: Lateral CXRs are taken in the left lateral position, meaning the left ribs are against the detector.
How can you differentiate L and R diaphragms on a lateral CXR?
- Left has stomach bubble under
- Left is not seen anteriorly (due to heart)
- Left is lower
What structure appears as “the dark hole” on a lateral CXR?
The left upper lobe bronchus (en face)
How can you differentiate the L and R main pulmonary arteries on a lateral CXR?
L pulmonary artery is posterior to “the dark hole” (en face bronchus)
R pa is anterior (and also more inferior)
Note: “L”osers to the back.
Retrotracheal triangle
Dark triangle behind the trachea on the lateral CXR (above the aortic arch and anterior to the spine)
Note: This should always be black.
Common reason for an opacified retrotracheal triangle
Aberrant right subclavian artery
Note: The retrotracheal triangle is the (usually) dark triangle behind the trachea on the lateral CXR (above the aortic arch and anterior to the spine).
Which “hilar point” should be superior?
The left hilar point should be ~1 cm above the right hilarity point on CXR
Note: The hilar point is the medially oriented “V” at the hill: > <
On lateral CXR, which major fissure is anterior?
The right major fissure is anterior to the left
How many layers of pleura make up an azygos lobe fissure?
4 (2 visceral and 2 parietal)
How many bronchopulmonary segments are there on the right?
10 (3 upper, 2 middle, and 5 lower)
How many bronchopulmonary segments are there on the left?
8 (4 upper and 4 lower)
What are the bronchopulmonary segments on the right?
- R upper (apical, posterior, anterior)
- R middle (medial and lateral)
- R lower (superior, anterior, posterior, medial, and lateral)
What are the bronchopulmonary segments on the left?
- L upper (apicoposterior, anterior, superior singular, and inferior lingular)
- L lower (superior, anteromedial, lateral, posterior)
Pig bronchus
AKA tracheal bronchus, a normal variant where the right upper lobe bronchus originates directly from the trachea
Note: May cause recurrent RUL pneumonia.
Cardiac bronchus
An accessory bronchus that originates from the right bronchus intermedius
Note: It is usually blind ending, but may cause recurrent infections.
What separates the superior mediastinum from the rest of the mediastinum?
A plane at the level of the sternomanubrial junction (also at the level of T4)
What is the posterior border of the anterior mediastinal space?
Pericardium
What is in the middle mediastinum?
- The heart
- Roots of central vessels (e.g. aorta)
- Tracheal bifurcation
- Phrenic nerves
What are the borders of the posterior mediastinum?
- Posterior pericardium
- Spine (anterior longitudinal ligament)
Note: Contains the esophagus, lower thoracic duct, and descending aorta.
What is the most anterior structure in the superior mediastinum?
The thymus
What is the normal number of pulmonary veins?
4
- R superior
- R inferior
- L superior
- L inferior
Note: This is highly variable.
Supernumerary pulmonary veins predispose to…
Atrial fibrillation
What is the most common supernumerary vein?
Right middle
What is the most common vein sleeve to cause atrial fibrillation?
Left superior pulmonary vein
What is a common ostium (in the context of pulmonary veins)?
A common origin of the left superior and inferior pulmonary veins (can also occur on the right)
Note: This is important to identify preop so that the common ostium isn’t ligated if you only want to remove the left upper lobe.
What are the 4 major etiologies of atelectasis?
- Obstructive (AKA absorptive)
- Compressive (AKA relaxation/passive)
- Fibrotic (AKA cicatrization)
- Adhesive
Common causes of obstructive atelectasis
- Obstructing neoplasm
- Mucous plugging
- Foreign body aspiration
Common causes of compressive atelectasis
- Pleural effusion
- Mass
- Hiatal hernia
- Large pulmonary bleb
Common causes of cicatrization atelectasis
Anything that causes fibrosis (e.g. tuberculosis and other infections, radiation scarring, etc.)
Note: Cicatrization occurs when fibrosis doesn’t allow the lung to fully expand.
Common causes of adhesive atelectasis
Insufficient surfactant:
- Respiratory distress syndrome (in preterm infants)
- ARDS
- Pulmonary embolism (loss of blood flow and lack of CO2 prevents surfactant from working)
What are the direct signs of atelectasis?
- Displacement of the fissures
- Crowding of vessels/bronchi in the atelectatic area
What are indirect signs of atelectasis?
- Opacified collapsed lung with a typical appearance
- Negative mass effect (e.g. shifting hilarity points up/down, tenting of the diaphragm, mediastinal shifting, rib space narrowing, etc.)
How can you differentiate acute vs chronic atelectasis?
Acute atelectasis tends to cause diaphragmatic/mediastinal/hilar displacement
Chronic atelectasis has less negative mass effect due to hyper expansion of the remaining lung (which appears as oligemia)
RUL collapse
Look for: RUL opacity, upward bowing of minor fissure, elevated right hilum
RUL collapse
Look for: RUL opacity, upward bowing of minor fissure, elevated right hilum, anterior bowing of superior oblique fissure
RML collapse
Look for: loss of the right heart border, downward bowing of the minor fissure
RML collapse
Look for: Anterior linear density over the heart
RLL collapse
Look for: Density at the right heart border, but right heart border is NOT silhouetted out, mediastinal vessels pulled to the right so far there is a triangle of black between them and the mediastinum (superior triangle sign)
RLL collapse
LUL collapse
Look for: Luftsichel sign, non visualization of the aortic knob, peaking of left diaphragm
LLL collapse
Look for: Opacity hidden behind heart, “flat waist sign” (linear appearance of the left heart border)
S sign of golden
A reverse S-shaped appearance of the minor fissure due to a centrally obstructing mass causing RUL collapse
Chronic right middle lobe collapse, think…
Lady Windermere syndrome (chronic MAI infection in an elderly woman who is too proper to cough)
Note: Look for small nodules and bronchiectasis with additional involvement of the lingual.
CXR showing loss of the right diaphragm and loss of the right heart border…
Think RLL and RML collapse
Luftsichel sign
A crescent of air surrounding the aortic knob (a sign of left upper lobe collapse)
Luftsichel sign (LUL collapse)
Hilum overlay sign
If you can see the hilar vessels through an overlying mass on CXR, then the mass is not in the hilum (it is anterior or posterior to the hilum)
Cervicothoracic sign
Any mass that extends above the clavicles is not in the anterior mediastinum (which ends at the clavicles)
What produces the posterior junction line on CXR?
Airspaces of the left and right lungs touching posterior to the trachea
Incomplete border sign on CXR
A peripheral mass with an incomplete border may be pleural or chest wall based (pulmonary masses should have a crisp border around the entire mass)
Classic presentation of Strep pneumo pulmonary infection?
Lobar consolidation
Note: Can be severe in sickle cell pts post splenectomy.
Classic presentation of Staph aureus pulmonary infection?
Bronchopneumonia (patchy opacities), often bilateral and may produce an abscess
Classic presentation of anthrax pulmonary infection?
Mediastinal widening and a pleural effusion in the setting of bio-terrorism
Note: This is due to hemorrhagic lymphadenitis, mediastinitis, and hemothorax.
Classic presentation of Klebsiella pulmonary infection?
“bulging fissure” due to exuberant inflammation (and more likely to have pleural effusions, empyemas, and cavitations) in an alcoholic or nursing home pt (aspiration risk)
Note: “currant jelly sputum”
Classic presentation of H influenza pulmonary infection?
Bronchitis in COPD pts and people without a spleen, but can also present as bilateral lower lobe bronchopneumonia (patchy opacities)
Classic presentation of pseudomonas pulmonary infection?
Patchy opacities with abscess formation in high risk pts (ventilated ICU pts, cystic fibrosis, or primary ciliary dyskinesia)
Classic presentation of Legionella pulmonary infection?
Peripheral and sublobar airspace opacity often in COPD pts or epidemic from water towers/air conditioners
Note: Only cavities in immunosuppressed pts.
Classic presentation of aspiration pneumonia?
Airspace opacities (cavitation and abscess are common) in the dependent portions of the lung
Which portions of the lung are most likely to develop aspiration pneumonia?
Posterior upper lobes and superior lower lobes (if pt supine during aspiration)
Basal lower lobes, lingual, and middle lobe (if pt upright during aspiration)
Note: More likely on the right than left.
Classic presentation of Actinomyces pulmonary infection?
Airspace opacities in the peripheral lower lobes +/- rib osteomyelitis/invasion of chest wall
Note: Classic story is a dental procedure gone bad, leading to mandibular osteomyelitis and aspiration.
Classic presentation of Mycoplasma pulmonary infection?
Fine reticular pattern on CXR and patchy airspace opacities with tree-in-bud nodules
Most common community-acquired pneumonia in 5-20 y/o?
Mycoplasma
Mycoplasma pneumonia is associated with what syndrome?
Sayer-James syndrome (classically appearing as a unilateral Lucent lung due to hyperinflation)
To exclude an underlying mass, a follow up CXR is recommended following pneumonia to confirm resolution when?
6 weeks later (young pt)
3 months later (elderly pt)
Classic appearance of graft vs host disease in the lungs s/p bone marrow transplant?
Bronchiolitis obliterates (seen as air trapping: mosaic attenuation on expiratory imaging)
Note: This usually occurs in the chronic (>100 days) phase of graft vs host disease.
Pulmonary findings s/p bone marrow transplant are divided into what three timeframes?
- Early neutropenic (0-30 days)
- Early (30-90 days)
- Late (>90 days)
What pulmonary findings are common in pts in the early neutropenic phase (0-30 days) s/p bone marrow transplant?
- Pulmonary edema
- Pulmonary hemorrhage
- Drug induced lung injury
- Fungal pneumonia (invasive aspergillosis)
What pulmonary findings are common in pts in the early phase (30-90 days) s/p bone marrow transplant?
- PCP
- CMV
What pulmonary findings are common in pts in the late phase (>90 days) s/p bone marrow transplant?
- Bronchiolitis obliterans
- Cryptogenic organizing pneumonia
Bilateral perihilar ground glass opacities in a pt with AIDS…
Think PCP
Note: There may also be cysts.
Most common cause of an airspace opacity in pts with AIDS…
Strep pneumoniae
“flame-shaped” perihilar opacities in a pt with AIDS…
Think Kaposi sarcoma
Persistent pulmonary opacities in a pt with AIDS…
Think lymphoma
Many pulmonary cysts in a pt with AIDS…
Think lipoid pneumonia
Note: PCP can have cysts in 30% of cases.
Lung cysts, ground glass opacities, and pneumothorax in a pt with AIDS…
Think PCP
Hypervascular lymph nodes in a pt with AIDS…
Think Castleman or Kaposi sarcoma
Pulmonary infection in a pt with CD4 > 200
- Bacterial infections
- Tuberculosis
Pulmonary infection in a pt with CD4 < 200
- PCP
- Atypical mycobacteria
Pulmonary infection in a pt with CD4 < 100
- CMV
- Disseminated fungal infection
- Mycobacterial infection
Acute focal airspace opacity in a pt with AIDS…
- Think bacterial infection (most commonly strep pneumonia)
- Think TB (if CD4 is on the lower end)
Chronic focal airspace opacity in a pt with AIDS…
Think lymphoma or Kaposi sarcoma
Ground glass opacities in a pt with AIDS…
Think PCP
Note: If not a choice and CD4 < 100, think CMV.
What are the different phases of pulmonary tuberculosis?
- Primary
- Primary progressive
- Latent
- Post primary (reactivation)
Common sequela of primary pulmonary TB
- Ghon focus (focal calcified granuloma formation)
- Ranke complex (Ghon focus + calcified hilar lymph nodes, more common in kids)
- Lobar atelectasis (if bulky lymphadenopathy cause compression)
Note: Cavitation is not common in primary TB.
What happens if a primary TB granuloma ruptures?
- Endobronchial spread
- Hematogenous spread, which can cause miliary TB if progression/reactivation
Primary progressive pulmonary TB
Local progression of TB infection with the development of cavitation (either at primary site or site of hematogenous spread)
Note: This is uncommon, but may occur in pts with immunosuppression (e.g. HIV).
Risk factors for primary progressive pulmonary TB
Immunosuppression:
- HIV
- Organ transplant
- Steroids
- Jejunoileal bypass
- Subtotal gastrectomy
- Silicosis
Latent pulmonary TB
When you have a positive PPD, but a negative CXR and no symptoms
Pt has a positive PPD with negative CXR in the setting of prior TB vaccination…
The US considers these pts to have latent TB (even though PPD positivity is likely due to vaccination) and pts are treated with 9 months of isoniazid
What percentage of latent TB will reactivate?
Approximately 5%
Where is reactivation TB most likely to occur?
Apical and posterior upper lobe and superior lower lobe
Note: These areas get more oxygen and less lymphatics.
When would you consider a TB pulmonary infection more likely to be latent?
When there is cavitation
Note: Also classic locations in the pulmonary apex/superior lower lobe.
Rasmussen aneurysm
An arterial pseudoaneurysm that develops due to pulmonary cavitation in tuberculosis
Pt with active tuberculosis develops sudden worsening after being started on HAART for HIV…
Immune reconstitution syndrome
Note: Treatment is with steroids.
Is pleural involvement common in TB?
Pleural effusions can occur any time after the primary infection, but is usually seen around 3-6 months after primary TB
Note: This is due to a hypersensitivity reaction (pleural fluid sampling is usually culture negative, you need to actually do a pleural biopsy to make the culture more sensitive).
Why is identifying cavitation important when diagnosing pulmonary TB?
Cavitation is rare in primary TB, so is suggestive of post primary (reactivation) or, less likely, primary progressive TB
When is miliary TB seen?
Hematogenous spread during post primary (reactivation) or primary progressive TB
When can a latent TB infection reactivate in pts with HIV?
Anytime, even if CD4 > 200
Note: Primary progressive TB usually only occurs if CD4 < 200.
What are the two most significant nontuberculous mycobacteria that cause pulmonary infections?
- Mycobacterial avium-intracellulare complex (MAC)
- Mycobacterium Kansasii
Upper lobe cavitary lesion with adjacent nodules suggesting end-bronchial spread in an older male with COPD…
Think nontuberculous mycobacterial infection (e.g. MAC or M. kansasii)
Elderly lady with tree-in-bud opacities and cylindrical bronchiectasis in the right middle lobe and lingula…
Think Lady Windermere syndrome (mycobacterium avium complex infection in the setting of an old lady too polite to cough)
HIV pt (CD4 < 100) with hepatosplenomegaly, MEDIASTINAL LYMPHADENOPTHY, and mixed pulmonary opacities…
Think nontuberculous mycobacterial infection
Note: This is a GI infection with hematogenous spread.
Ill defined ground glass centrilobular nodules in a pt with recent history of hot tub use…
Think nontuberculous mycobacterial infection (hot tub lung)
What are the three categories of pulmonary aspergillus infections?
- Normal immunity (e.g. aspergilloma)
- Immunosupressed (e.g. invasive aspergillosis)
- Hyper-immune (e.g. allergic bronchopulmonary aspergillosis)
Otherwise healthy pt with a solid mass sitting dependently in a pulmonary bleb or cavity…
Think aspergilloma in a pre-existing cavity
Note: Confirm that the fungus ball moves dependently with different positions.
When should you be concerned about invasive pulmonary aspergillosis?
- Immunocompromised pt (e.g. AIDS, organ transplant)
- Halo sign (consolidate nodule/mass with a ground glass “invasive” halo)
- Air crescent sign (a thin crescent of air within a consolidative mass)
Upper lobe central saccular bronchiectasis with mucoid impaction (finger-in-glove opacities) in a pt with long standing asthma…
ABPA (allergic bronchopulmonary aspergillosis)
Agressive pulmonary infection with invasion of the mediastinum, pleura, and chest wall in a pt with AIDS and uncontrolled diabetes…
Think mucormycosis (aggressive fungal infection in high risk pts)
Multiple groundglass and/or consolidate nodules in a pt who had a bone marrow transplant 45 days prior…
Think cytomegalovirus infection
Note: Classic scenarios for CMV pulmonary infection is reactivation after prolonged immunosuppression (e.g. AIDS, organ transplant) or a bone marrow transplant with CMV positive marrow.
Classic appearance of CMV pulmonary infection?
Multiple groundglass or consolidate nodules in immunocompromised pt
Classic appearance of measles pulmonary infection?
Multifocal ground glass opacities with small nodular opacities
Note: Pneumonia can occur before or after measles skin lesions.
Classic appearance of influenza pulmonary infection?
Coalescent lower lobe opacity
Note: Pleural effusions are rare.
Classic appearance of varicella pulmonary infection?
Multiple peripheral nodular opacities that become calcified after healing in an immunocompromised adult (e.g. AIDS, lymphoma)
Classic appearance of Epstein Barr virus pulmonary infection?
Lymph node enlargement and splenomegaly
Note: lung opacities are rare.
What is the radiographic definition of severe COVID19?
> 50% pulmonary involvement on imaging within 24-48 hours
Classic appearance of COVID19?
Bilateral peripherally-based ground glass opacities with or without “reversed halos” (ground glass opacity surrounded by consolidation)
Note: Pleural effusions are uncommon.
CT findings in the late/absorption state of COVID19
“fibrous stripes” (e.g. sub pleural bands) in the regions of previous disease
Common sources of septic emboli to the lungs
- Infected tricuspid valve
- Systemic infection
- Infected catheters
- Dental infections
Classic appearance of septic emboli to the lungs
Peripheral round caveating nodules (some may show a large feeding vessel suggestive of hematogenous spread) with a lower lobe predominance (due to increased dependent blood flow)
Lemierre syndrome
Jugular vein thrombosis in the setting of oropharyngeal infection with septic pulmonary emboli
Note: Commonly there is a recent ENT surgery.
What is the bacterial agent responsible for the majority of septic pulmonary emboli?
Fusobacterium necrophorum
Common causes of pulmonary cavitating disease
CAVITY:
- Cancer (usually squamous cell)
- Autoimmune (Wegners, Rheumatoid, Caplan syndrome)
- Vascular (septic emboli, bland emboli)
- Infection (TB)
- Trauma (pneumatoceles)
- Young (congenital: CCAMs, sequestrations)
What is the cutoff between a pulmonary nodule and a pulmonary mass?
3 cm
What are the 4 major “benign calcification” patterns for a pulmonary nodule?
- Solid/diffuse
- Laminated (concentric)
- Central
- Popcorn
Note: Any other types of calcifications are considered suspicious.
What are some common suspicious calcifications patterns for pulmonary nodules?
- Eccentric
- Stippled (many small flecks)
What medical histories should make you suspicious of what would otherwise be considered benign appearing calcifications in a pulmonary nodule?
- GI cancer (can have pulmonary mets with popcorn or central calcifications)
- Osteosarcoma (can have pulmonary mets with solid calcifications)
What findings suggest that a pulmonary nodule is benign?
- Macroscopic fat
- Slow doubling time (longer than 16 months)
- Rapid doubling time (shorter than 1 month)
What pulmonary nodule findings are suspicious for cancer?
- Spiculated margins (corona radiata)
- Air bronchograms running through the nodule (suggestive of adenocarcinoma)
- Partially solid lesions with a ground glass component
- Moderate doubling time (>1 month, but less than 16 months)
Are solid or ground glass pulmonary nodules more concerning?
- Part solid part ground glass (most concerning)
- Entirely ground glass (concerning)
- Entirely solid (least concerning)
Should solitary pulmonary nodules that are malignant be hot on PET/CT?
If the nodule is solid, FDG uptake is suspicious for cancer
If the nodule is groundglass, FDG uptake is more suggestive of infection/inflammation (cold ground glass nodules are suspicious for cancer)
Note: The nodule must be 1 cm or more to be within the resolution of PET/CT.
Can perifissural nodules be spherical?
No, this suggests a pulmonary nodule that is growing through the fissure rather than along it (more concerning for cancer, less likely to be an intro pulmonary lymph node)
Lung cancer is more commonly found in which lung?
The right lung (1.5x)
Where in the lung is lung cancer most likely to be found?
Upper lobes (70%)
Note: In pulmonary fibrosis, lung cancer is more commonly found in the lower lobes.
A ground glass pulmonary nodule gets smaller and more dense on follow up imaging…
Suspicious for neoplasia
Note: Just because a pulmonary nodule get smaller doesn’t mean its benign, especially if it gets more dense.
A new solitary pulmonary nodule in a pt with known head and neck cancer…
More likely to be a primary bronchogenic carcinoma rather than a metastases (these types of cancers have similar risk factors)
Do air bronchograms make a solitary pulmonary nodule more or less likely to be neoplastic?
Air bronchograms are 5x more common in malignant solitary pulmonary nodules
Who qualifies for lung cancer screening?
Adults age 50-80 years with a 20 pack year history of smoking (and are currently smoking or have quit within the past 15 years)
What is the radiation dose for lung cancer screening chest CTs?
Low dose: recommended to be less than CTDI(vol) 3 mGy
What is the maximum slice thickness for a low dose chest CT for lung cancer screening?
2.5 mm (though most recommend 1.5 mm or thinner)
What is considered “growth” on lung cancer screening chest CTs?
Increase of 1.5 mm or more in one year
How are end-bronchial lesions treated during lung cancer screening?
Category 4a (suspicious), with recommendation for a 3 month follow up scan
Note: Many of these will end up just being mucous.
Can people with a history of prior lung cancer be enrolled in a lung cancer screening program?
Yes, but the lung cancer must be treated and remote (> 5 years)
How should lung nodule sizes be reported on lung cancer screening chest CTs?
To the 0.1 mm (e.g. 7.9 mm)
Which lung rads categories require shorter term follow-up than the standard annual chest CT?
Categories 3 and 4
Note: Category 0 (incomplete) requires a repeat scan or comparison with priors.
Lung-RADS category 0
Incomplete exam
Note: Needs repeat scan or comparison with priors that aren’t available.
Lung-RADS category 1
Negative (no nodules or only granulomas)
Note: Continue annual chest CT.
Lung-RADS category 2
Benign
Baseline: No nodules 6 mm or more
Subsequent: No new nodules 4 mm or more, ground glass nodules 30 mm or more, or perifissural nodules 10 mm or more.
Note: Continue annual chest CT.
Lung-RADS category 3
Probably benign
Baseline: Nodules 6-8 mm
Subsequent: New nodule 4 mm or more. Ground glass nodule 30 mm or more.
Note: Recommend 6 month follow up chest CT.
Lung-RADS category 4a
Suspicious (5-15% chance of cancer)
Baseline: Nodules 8-15 mm
Subsequent: New nodule 6-8 mm
Note: Recommend 3 month follow up chest CT or PET/CT.
Lung-RADS category 4b
Suspicious (>15% chance of cancer)
Baseline: Nodules 15 mm or more
Subsequent: New nodule 6 mm or more
Note: Recommend PET/CT or tissue sampling.
Lung-RADS category 4x
Suspicious (>15% chance of cancer)
Baseline: N/a
Subsequent: worsening of category 3 or 4 nodules (growth or new spiculation)
Note: Recommend PET/CT or tissue sampling.
What are the Lung-RADS categories and recommendations
- 0 (incomplete, repeat scan or get priors)
- 1 (negative, continue annual)
- 2 (benign, continue annual)
- 3 (probably benign, repeat chest CT in 6 months)
- 4a (suspicious, repeat chest CT in 3 months or PET)
- 4b (suspicious, PET or tissue sampling)
- 4x (suspicious, PET or tissue sampling)
When do you use Lung-RADS vs Fleischner guidelines?
Lung-RADS is only used for low-dose CTs for lung cancer screening
Fleischer guidelines are used for nodules incidentally discovered on non-screening chest CTs (with some exceptions)
When should Fleischner guidelines NOT be used?
- Pts under age 35
- Pts with known or suspected cancer
- Immunocompromised pts
How should solid pulmonary nodules be measured according to the Fleischner Society?
Average of longest diameter and perpendicular diameter measured in the same plane (usually axial)
Why is it recommended to evaluate pulmonary nodules using slice thickness of 1.5 mm or less?
To look for a small solid component within a ground glass nodule (which might not be seen on thicker slices due to volume averaging)
Follow up recommendations for a low-risk solitary solid pulmonary nodule according to Fleiscner guidelines
- <6 mm (no follow up)
- 6-8 mm (6-12 month repeat chest CT)
- > 8 mm (PET or biopsy)
Follow up recommendations for a high-risk solitary solid pulmonary nodule according to Fleiscner guidelines
- <6 mm (12 month repeat chest CT)
- 6-8 mm (6-12 month repeat chest CT)
- > 8 mm (PET or biopsy)
Follow up recommendations for low-risk multiple solid pulmonary nodules according to Fleiscner guidelines
- <6 mm (no follow up)
- 6-8 mm (3-6 month repeat chest CT)
- > 8 mm (3-6 month repeat chest CT)
Note: Recommendation according to largest nodule.
Follow up recommendations for high-risk multiple solid pulmonary nodules according to Fleiscner guidelines
- <6 mm (12 month repeat chest CT)
- 6-8 mm (3-6 month repeat chest CT)
- > 8 mm (3-6 month repeat chest CT)
Note: Recommendation according to largest nodule.
Recommendation for solitary incidental solid pulmonary nodule <6 mm
- No follow up (low risk)
- 12 month repeat chest CT (high risk)
Recommendation for solitary incidental solid pulmonary nodule 6-8 mm
6-12 month repeat chest CT (low and high risk)
Recommendation for solitary incidental solid pulmonary nodule >8 mm
PET or biopsy (low and high risk)
Recommendation for multiple incidental solid pulmonary nodules measuring up to <6 mm
- No follow up (low risk)
- 12 month repeat chest CT (high risk)
Recommendation for multiple incidental solid pulmonary nodules measuring up to 6-8 mm
3-6 month repeat chest CT (low and high risk)
Recommendation for multiple incidental solid pulmonary nodules measuring up to >8 mm
3-6 month repeat chest CT
Note: This recommendation is less stringent than for solitary pulmonary nodules, which have a higher chance of malignancy.
Follow up recommendations for incidental solitary ground glass pulmonary nodules
- <6 mm (no follow up)
- 6 mm or more (6-12 month repeat chest CT, then every 2 years until resolution up to a total of 5 years)
Note: Follow-up is extended to 5 years if 6 mm or more due to the potential for slow growing adenocarcinoma in situ.
Follow up recommendations for incidental multiple ground glass pulmonary noduels
3-6 month repeat chest CT
When can a solitary solid pulmonary nodule stop being followed?
If it is stable for 2 years or more
Follow up recommendations for an incidental part solid pulmonary nodule
- <6 mm (no follow up)
- 6 mm or more (3 month repeat chest CT, then repeated at widening intervals for a total of 5 years if persistent)
What are the main histologic subtypes of bronchogenic carcinoma?
- Non small cell (adenocarcinoma, squamous, and large cell)
- Small cell
Which bronchogenic carcinoma subtypes are more likely to be found peripherally?
- Large cell
- Adenocarcinoma
Note: “LA” is on the coast. squamous and small cell carcinomas are mote likely to be central.
What bronchogenic carcinoma subtype is most common in non-smokers?
Adenocarcinoma
Note: This subtype is also common in smokers.
Which bronchogenic carcinoma subtype is most likely to cavitate?
Squamous cell carcinoma
Which bronchogenic carcinoma subtype is associated with ectopic parathyroid hormone production?
Squamous cell carcinoma
Which bronchogenic carcinoma subtype is most common?
Adenocarcinoma
What is the most common bronchogenic carcinoma subtype to present as a solitary pulmonary nodule?
Adenocarcinoma
What is the most common bronchogenic carcinoma subtype to cause SVC obstruction and paraneoplastic syndromes?
Small cell carcinoma
Which bronchogenic carcinoma subtype has the strongest association with smoking?
Small cell carcinoma (nonsmokers virtually never get small cell carcinoma)
Which bronchogenic carcinoma subtype may present with only central lymphadenopathy?
Small cell carcinoma
Note: Small cell carcinoma tends to metastasize early.
What paraneoplastic syndromes are associated with small cell lung cancer?
- SIADH
- Ectopic ACTH production
- Lambert-Eaton syndrome
68 y/o smoker who presents with proximal muscle weakness with chest CT demonstrating mediastinal/hilar lymphadenopathy…
Think small cell carcinoma with the Lambert-Eaton syndrome (paraneoplastic syndrome)
Which bronchogenic carcinoma subtype is associated with the Lambert-Eaton paraneoplastic syndrome?
Small cell carcinoma
Which bronchogenic carcinoma subtype has the worst prognosis?
Small cell carcinoma (metastasizes early)
What are presenting symptoms that can help predict whether a lung cancer is peripheral or central?
- Hemoptysis (central lung cancer)
- Pleuritic chest pain (peripheral lung cancer)
Which bronchogenic carcinoma subtype has an association with pulmonary fibrosis?
adenocarcinoma
What is adenocarcinoma in situ?
A localized adenocarcinoma that is <3 cm and exhibits a lepidocrocite growth pattern with neoplastic cells along the alveolar structures (but no stroll/vascular/pleural invasion)
What is the spectrum of adenocarcinoma?
Pre-invasive lesions:
- Atypical adenomatous hyperplasia of lung (usually a small <5 mm ground glass nodule)
- Adenocarcinoma in situ (usually 5-30 mm part solid nodule)
Invasive lesions:
- Minimally invasive adenocarcinoma (<5 mm of stromal invasion)
- Invasive mutinous adenocarcinoma (used to be called bronchoalveolar carcinoma)
Note: These tend to progress from groundlass to part solid to solid/invasive.
Which lung cancer subtype is classically cold on PET/CT?
Adenocarcinoma in situ spectrum (lepidic growth appearing as a ground glass nodule getting progressively more dense)
What are the symptoms associated with a pancoast tumor?
- Shoulder pain
- C8-T12 radiculopathy
- Horner syndrome (ptosis/droopy eyelid and miosis/small pupil)
What is the best way to stage pancoast tumors?
MRI (to evaluate the brachial plexus)
What are general contraindications to surgical resection of a pancoast tumor?
- Vertebral body invasion >50%
- Spinal canal invasion
- Involvement of the upper brachial plexus (C8 or higher)
- Diaphragm paralysis (due to C3-C5 involvement)
- Distal metastases
What is a pancoast tumor?
An apical pulmonary tumor with associated symptoms (shoulder pain, Horner syndrome, etc.)
T classification of lung cancer staging by size
- T1 (<3 cm)
- T2 (3-5 cm)
- T3 (5-7 cm)
- T4 (>7 cm)
What characteristics make a lung cancer T2 even if smaller than 3 cm?
- Invasion of visceral pleura
- Invasion of a main bronchus (without involvement of the carina, which would make it T4)
- Causes obstruction (atelectasis or pneumonia) that extends to the hilum
What characteristics make a lung cancer T3 even if smaller than 5 cm?
- Invasion of the chest wall
- Invasion of the pericardium
- Invasion of the phrenic nerve (diaphragmatic paralysis)
- One or more satellite nodules in the same lung lobe
- Pancoast tumor involving the T1/T2 nerve roots
What characteristics make a lung cancer T4 even if smaller than 7 cm?
- Invasion of mediastinal fat or great vessels
- Invasion of the diaphragm
- Involvement of the carina
- One or more satellite nodules in the same lung, but a different lobe
- Pancoast tumor involving the C8 nerve roots or higher
T classification of a lung cancer that involves the intrapericardial portion of the pulmonary veins
T4
N staging of lung cancer
- N0 (no nodal involvement)
- N1 (Ipsilateral nodal involvement up to the hilar nodes)
- N2 (ipsilateral mediastinal or subcarinal nodes), often not resectable
- N3 (contralateral mediastinal/hilar nodes OR scalene/supraclavicular nodes), rarely resectable
Note: PET/CT is the preferred method for N staging.
What is an important anatomical boundary when evaluating N stage in lung cancer?
Level 1 lymph nodes (above the upper border of the manubrium/lower border of the clavicles), indicates N3 stage
Note: Level 2 lymph node involvement (below manubrium/clavicles) indicates N2 stage.
What are typical contraindications to lobectomy of lung cancer?
- Growth of tumor through a fissure
- Invasion of pulmonary vasculature
- Invasion of main bronchus
- Invasion of both upper and lower lobe bronchi
What are typical contraindications to resection of lung cancer?
- N3 nodal disease (contralateral mediastinal/hilar nodes OR scalene/supraclavicular nodes)
- Tumor >5 cm AND N2 disease (ipsilateral mediastinal/subcarinal nodes)
- Multi-lobar disease
- Malignant pleural effusion
Which mediastinal nodes are not easily reached by mediastinoscopy and therefore important for the radiologist to identify prior to mediastinoscopy?
Prevascular lymph nodes
Treatment of a stage 1A or 1B lung cancer that is peripheral and <2 cm…
Wedge resection (to preserve more pulmonary reserve than a lobectomy)
Note: In general, if the tumor is >3 cm, lobectomy is usually a better option.
Following a pneumonectomy for lung cancer, there is progressively increasing air in the pneumonectomy cavity over the following 3 days…
Bronchopleural fistula
What are the risk factors for a bronchopleural fistula following a pneumnectomy?
- Ischemia of the bronchi (due to disrupted blood supply from aggressive lymph node dissection)
- Using a long bronchial stump
Postpneumonectomy syndrome
A compensatory emphysema following pneumonectomy, where the contralateral lung hyperexpands to compensate for the absent contralateral lung
How do radiation changes appear in the lung following radiotherapyfor lung cancer?
- Homogenous or patchy ground glass opacities (early: 1-3 months)
- Dense consolidation, traction bronchiectasis, and volume loss (late)
Is it common to develop rib fractures within the radiation field s/p treatment for lung cancer?
Yes, ribs within the radiation field are susceptible to degradation and fracture
Bubbles found within a pulmonary lesion immediately following radio frequency/microwave ablation…
Bubbles are a normal finding post RFA/MWA
What is the best way to evaluate for recurrent lung cancer s/p treatment?
Look for enhancing areas with a round morphology (radiation changes should not have a round morphology and should not increase in size over time)
Note: Focus on the periphery of the radiation bed, regional lymph nodes, and the bronchial stump.
New pleural effusion s/p treatment for lung cancer that persists on follow up imaging…
Suspicious for recurrent lung cancer
Pulmonary lesion with macroscopic fat and popcorn calcifications…
Pulmonary hamartoma
What is the most common benign lung mass?
Pulmonary hamartoma
Are pulmonary hamartomas symptomatic
Usually not, but they can be if they are end-bronchial (2% of cases)
Pulmonary lesion with macroscopic fat that is FDG avid on PET…
Pulmonary hamartoma (benign lesion, but can still be hot on PET)
What is the most common lung tumor in AIDS pts?
Kaposi sarcoma (followed by lymphoma)
Flame shaped consolidation along the perihilar pulmonary parenchyma in an AIDS pt (CD4 < 200)…
Think Kaposi sarcoma
What is the most common hepatic neoplasm in AIDS pts…
Kaposi sarcoma
Common findings of pulmonary kaposi sarcoma in an AIDS pt
- Flame shaped central opacities
- Slow growth without symptoms
- Bloody pleural effusion
- Thallium positive and gallium negative
What are the 3 categories of metastatic disease to the lungs?
- Direct invasion
- Hematogenous metastases
- Lymphangitic carcinomatosis
What tumors most commonly cause direct invasion of the pulmonary parenchyma?
- Esophageal carcinoma
- Lymphoma
- Malignant germ cell tumor
- Pleural metastases
- Malignant mesothelioma
Note: Cancers of the mediastinum, pleura, or chest wall are most likely to directly invade the lungs.
How do hematogenous metastases to the lungs appear?
Diffuse pulmonary nodules with a random distribution and a lower lobe predominance (due to greater blood volume)
Which primaries are most likely to produce “cannonball” pulmonary metastases?
- Renal cell carcinoma
- Testicular choriocarcinoma
Pulmonary hematogenous metastases are most likely from which primary tumors?
- Breast
- Kidney
- Thyroid
- Colon
- Head and neck squamous cell carcinoma (often cavitating)
Prominent pulmonary vessels leading to pulmonary nodules…
Think hematongeous metastases or septic emboli
What is the most common primary in lymphangitis carcinomatosis?
Bronchogenic carcinoma invading the lymphatics
Note: The most common extra thoracic primaries are breast, stomach, pancreas, and prostate cancers.
What are the 4 main categories of pulmonary lymphoma?
- Primary lymphoma
- Secondary lymphoma
- AIDS-related lymphoma
- Post-transplant lymphoproliferative disorders (PTLDs)
What is the most common subtype of primary pulmonary lymphoma?
Non-Hodgkin, low grade MALToma (80% of primary pulmonary lymphoma cases)
Primary pulmonary lymphoma
Pulmonary lymphoma without extrathoracic involvement for 3 months
Note: This is much more rare than secondary pulmonary lymphoma.
Secondary pulmonary lymphoma
Pulmonary involvement of a systemic lymphoma
If there is secondary pulmonary lymphoma, is this more likely to be Hodgkin or non-Hodgkin?
non-Hodgkin
Note: Although Hodgkin lymphoma is more likely to involve the lungs, non-Hodgkin lymphoma is much more common in general.
Pulmonary parenchymal involvement in seconday lymphoma without mediastinal involvement is likely to be what type of lymphoma?
non-Hodgkin
Note: If there is pulmonary involvement in Hodgkin lymphoma, there is almost always also mediastinal lymph node involvement as well.
Post transplant lymphoproliferative disorders
B-Cell lymphoma secondary to Epstein Barr virus infection following a solid organ or stem cell transplant
Note: This usually occurs within 1 year of the transplant, but can happen later (later ones are usually more aggressive).
AIDS pt with CD4 < 100 and pulmonary nodules, pleural effusions, and lymphadenopathy…
AIDS-related pulmonary lymphoma
AIDS-related pulmonary lymphoma
A high grade non-Hodgkin lymphoma that occurs in AIDS pts with CD4 < 100 secondary to epstein barr virus infection
Note: Extranodal involvement is common (CNS, bone marrow, lung, liver, bowel).
What nuclear medicine tests can help distinguish pulmonary Kaposi sarcoma from pulmonary lymphoma?
Thallium-201 and Gallium-67 scans
Note: Both will be positive on Thallium scans (live tissue), but only lymphoma will be gallium positive (inflammatory).
What tissues light up on thallium scans?
Anything that is alive (i.e. has a functional Na/K ATPase pump
Note: Thallium is a potassium analog.
What tissues light up on a gallium scan?
Inflamed tissues (infection, sarcoid, most cancers)
Note: Gallium is an iron analog (acute phase reactant analog). Things that are “smoldering” tend to be gallium-negative.
Which lymphomas are Gallium-positive
Most lymphomas are gallium positive, especially Hodgkin lymphoma. Some Non-Hodgkin subtypes can be gallium-negative, which is why PET/CT is used for staging and not gallium.
Poland syndrome
Congenital unilateral absence of a pectoral muscle, which can appear as a unilateral hyper lucent chest on radiographs
Note: Often associated with ipsilateral limb abnormalities (small/abnormal arms/hands).
Bronchial atresia
Congenital obliteration of a shirt segment of a lobar/segmental/subsegmental bronchus near its origin (most often affecting the apical-posterior segment of the left upper lobe)
Next step if you see hyperlucency and oligemia of the left upper lobe apical-posterior segment with a perihilar nodule demonstrating finger-in-glove morphology…
Bronchoscopy
Note: This is most likely bronchial atresia with mucoid impaction of the blind-ending bronchus, but could also be an obstructing endobronchial tumor.
Why does bronchial atresia lead to hyperlucency of the obliterated pulmonary segments?
Collateral air flow through the various pores of Kohn and canals of Lambert
When can you be confident that a perihilar nodule is due to mucoid impaction from bronchial atresia rather than an obstructing endobronchial tumor?
If you can measure a low density focus (<25 HU), you can safely call it mucoid impaction.
Note: If you cannot measure this low density focus, then you should get bronchoscopy to rule out an endobronchial tumor.
What symptoms are associated with bronchial atresia?
Usually asymptomatic, but can be associated with recurrent pneumonias
When should a pulmonary AVM be treated?
If the afferent vessel measures 3 mm or more
Pulmonary AVMs are associated with…
- Hereditary hemorrhagic telangiectasia
- Osler Weber Rendu
Where are pulmonary AVMs most likely to be found?
Lower lobes (due to increased blood flow)
What are possible significant complications of a pulmonary AVM?
Strokes and brain abscesses (due to right to left shunting)
Homogenous, well-circumscribed pulmonary nodule with intense enhancement and a feeding artery and draining vein…
Pulmonary AVM
What is the most common congenital venous anomaly of the chest?
Persistent left SVC
Where does a persistent left SVC usually drain to?
The coronary sinus, though in 5% of cases can drain directly to the left atrium causing a mild right to left shunt
Central line appears in a left paramedial location and terminates in the left atrium…
Think about persistent left SVC draining into the left atrium
Swyer-James syndrome
Unilateral hyperlucent lung secondary to post infectious obliterative bronchiolitis
Note: The size of the affected lobe is smaller than the normal lobe (not hyperexpanded, as in bronchial atresia).
Horseshoe lung
A rare congenital anomaly where there is fusion of the posterior basilar segments of the bilateral lower lobes
Note: This is associated with Scimitar syndrome.
Horseshoe lung is associated with…
Scimitar syndrome
Note: Horseshoe lung is fusion of the posterior basilar segments of the bilateral lower lobes.
Upper-mid lung zone predominant cysts with bizarre shapes in a smoker sparing the costophrenic angles…
Pulmonary Langerhans cell histiocytosis
Which cystic lung disease is associated with chylothorax development?
LAM (lymphangiomyomatosis)
Pulmonary langerhans cell histiocytosis has what pulmonary distribution?
Upper/midzone predominant cysts sparing the costophrenic angles
Note: LCH starts out with centrilobular nodules that then cavitate into cysts which coalesce into bizarre, thick-walled cystic cavities.
Treatment for pulmonary langerhans cell histiocytosis
Stop smoking (50% of cases spontaneous resolve)
Epidemiology of lymphangiomyomatosis (LAM)
Young women of child bearing age (LAM is estrogen-dependent)
Lymphangiomyomatosis (LAM) is associated with…
Tuberous sclerosis
Note: Look for TS triad (seizures, mental retardation, facial angiofibromas) or multiple renal angiomyolipomas in addition to diffuse pulmonary cysts.
Lymphangiomyomatosis has what pulmonary distribution?
Diffuse thin-walled cysts with uniform distribution
Treatment for lymphangiomyomatosis
Hormonal therapy (tamoxifen)
Note: Cysts usually progress despite treatment.
Diffuse pulmonary cysts in a pt with multiple renal angiomyolipomas…
Lymphangiomyomatosis (LAM) in a pt with tuberous sclerosis
Diffuse pulmonary cysts in a pt with seizures, intellectual disability, and facial angiofibromas…
Lymphangiomyomatosis (LAM) in a pt with tuberous sclerosis
What are the renal findings associated with Birt-Hogg-Dube syndrome?
- Bilateral oncocytomas
- Chromophobe renal cell carcinomas
Birt-Hogg-Dube syndrome
Multi-system disease characterized by:
- Cutaneous manifestations (typically fibrofolliculomas)
- Multiple lung cysts predisposing to spontaneous pneumothoraces
- Renal tumors (oncocytomas, chromophobe renal cell carcinomas)
Thin-walled, oval, “floppy” pulmonary cysts with lower lobe predominance in a pt with innumerable skin lesions…
Birt-Hogg-Dube syndrome
Note: Predisposed to cutaneous fibrofolliculomas and renal tumors (oncocytomas and chromophobe RCC)
Pulmonary cysts in Birt-Hogg-Dube syndrome have what distribution>
Lower zone predominance, favoring the paramediastinal regions, with thin-walled oval/floppy morphology
Lymphocytic interstitial pneumonitis (LIP)
A benign lymphoproliferative disorder associated with autoimmune diseases (SLE, PA, Sjogrens) resulting in cystic lung disease
Lymphocytic interstitial pneumonitis (LIP) is associated with…
- Autoimmune diseases in adults (mostly Sjogrens, also SLE and RA)
- HIV in kids
- Castleman disease
Thin-walled cysts in the deep pulmonary parenchyma in a pt with sicca syndrome…
Lymphocytic interstitial pneumonitis (LIP) in a pt with Sjogrens (presenting with sicca syndrome)
Perivascular pulmonary cysts…
Think lymphocytic interstitial pneumonitis (LIP)
What is the most common opportunistic pulmonary infection in AIDS pts?
Pneumocystis pneumonia (PCP)
AIDS pt with ground glass opacities predominantly in the hilar and mid lung zones…
Think pneumocystic pneumonia (PCP)
Apical pulmonary cysts in an AIDS pt with hilar/mid lung zone ground glass opacities…
Cystic form of pneumocystis pneumonia (PCP)
Note: The cystic form most often occurs in AIDS pts receiving aerosolized prophylaxis and predisposes to pneumothorax development.
AIDS pt with a new pneumothorax…
Think pneumocystis pneumonia (PCP)
Note: The cystic form that is common in pts receiving aerosolized prophylaxis is associated with pneumothorax development.
Vanishing lung syndrome
Defined as bullous disease occupying at least one-third of a hemithorax
Note: This is due to avascular necrosis of the lung parenchyma and hyperinflation, leading to giant bullous emphysema favoring the bilateral upper lobes.
Epidemiology of vanishing lung syndrome
Young males
Note: 20% of cases have alpha-1 antitrypsin deficiency.
Major complication of vanishing lung syndrome
Tension pneumothorax
