3.2: Week 3 pt 2

Question 1

Where is the anterior mediastinum?

Answer 1

Back of the sternum to anterior border of heart and great vessels

Question 2

Describe substernal thyroid masses

Answer 2

Note displaced trachea
Most often above the aortic arch
Dx: Radioisotope thyroid scans
On CT is continuous with the thyroid

Question 3

What is the most common cause of mediastinal mass overall? Explain

Answer 3

Note that lymphadenopathy is the most common cause of mediastinal mass overall—but LAD does not always equal lymphoma
Could also be metastasis, sarcoid, TB

Question 4

Describe lymphoma’s presentation

Answer 4

Lymphoma is often painless and found in many nodes
Often anterior
Usually bilateral and asymmetrical
Lobulated contour (clumps of nodes)

Question 5

Describe lymphomas on CTs

Answer 5

Multiple, lobulated soft-tissue masses
Homogenous
Unless the tumor
undergoes necrosis
or hemorrhage

Question 6

What is a thymoma? Where do they arise?

Answer 6

Neoplasm of thymic epithelium and lymphocytes
Middle-aged folks
Usually benign
Smooth or lobulated
Arise near junction of the heart and great vessels

Question 7

Describe thymomas and MG and why the correlation matters

Answer 7

Tumor associated with myasthenia gravis 35% of the time
But pts with MG have thymoma 15% of the time
Why does this correlation matter?
Because when you perform thymectomy, the MG often resolves!

Question 8

Thymomas have ________ margins

Answer 8

smooth

Question 9

Describe teratomas. Are they malignant?

Answer 9

Most often benign and found incidentally
However, 30% are malignant
Most common is Cystic
Contains all three germinal layers
Well-marginated, containing fat, cartilage and sometimes even bone

Question 10

What do cystic teratomas look like on imaging?

Answer 10

Well-marginated
Occurring near great vessels

Question 11

Middle Mediastinum: Where is it? What does it contain?

Answer 11

1) From the front to the back of the heart
2) Contains heart, origins of great vessels, trachea, and main bronchi
3) Also contains lymph nodes

Question 12

Why is the fact that the middle mediastinum contains lymph nodes important?

Answer 12

Which is important, because LAD is the most common source of masses in this compartment
However, malignancy can also produce LAD here—including small cell lung cancer and metastatic disease
Benign LAD may be due to mono and TB (usually unilat)

Question 13

What does the posterior mediastinum contain? What kind of tumors occur?

Answer 13

Contains: Descending aorta, esophagus, lymph nodes
Some of tumors of neural origin
Think about the spinal cord. . .
Neurogenic tumors
Soft tissue mass, usually with sharp margins

Question 14

A __________ can be an example of a large posterior mediastinum mass

Answer 14

Neurofibroma

Question 15

Solitary masses:
1) Less than ___ cm rarely become malignant
2) More than ____ cm is bad news

Answer 15

1) 4 cm
2) 5 cm

Question 16

How do you find if a nodule/ mass is solid or subsolid? Explain

Answer 16

This is a finding on CT
If subsolid, then may be purely ground-glass or partly solid and partly ground-glass
This “ground glass” appearance refers to increased attenuation (whiter area) on CT, in which the vessels and lung tissue are preserved rather than obliterated by it

Question 17

Solitary nodule <3cm: Differentiate low vs high risk patients

Answer 17

1) Low-risk patients: Younger age, minimal or no smoking history, regular margin to nodule, location of nodule in an area other than upper lobe.
2) High-risk patients: Older age, heavy smoker, upper lobe location, irregular or spiculated nodule margins

Question 18

Causes of the happy nodule (benign, though not necessarily great) include?

Answer 18

1) Granulomas: TB and histoplasmosis can create calcified nodules
2) Hamartoma: Peripheral tumors of disorganized tissue containing fat and calcium
3) Others: Rheumatoid nodules, fungal diseases, AV malformations, granulomatosis with polyangiitis

Question 19

List the modified ABCDEs

Answer 19

Asymptomatic? / risk factors?
Border
Consistency: Calcified, Solid vs subsolid
Diameter (3cm)
Evolution

Question 20

Describe the presentation of Bronchogenic Carcinoma

Answer 20

-Primary cancer presents as solitary nodule
-Irregular, spiculated border
-May cavitate
-May create secondary obstruction leading to pneumonitis or atelectasis
-Most often adenocarcinomas

Question 21

Bronchogenic Carcinoma: What are two sequela of obstruction?

Answer 21

Atelectasis and pneumonitis

Question 22

Metastatic Neoplasm in the Lung:
1) What do they look like?
2) What do you need to do?

Answer 22

1) Usually when you see multiple nodules in the lung
Varied sizes indicating varied stages of development
Can be micronodular to cannonball sized
2) Will have to use bronchoscope with bx to determine the source

Question 23

Define PE. What causes it?

Answer 23

Blood clot to the lung
Most commonly originating in the leg (DVT); can also be bc of surgery, CA, stasis > think ponds – sludge

Question 24

What tests do you need to get for PE?

Answer 24

1) CHEST X RAY IS A VERY POOR TOOL FOR DIAGNOSING PE; many false negatives on CXR
2) You need a CT angiogram
3) If you can’t get a CTA, VQ is the next best test, though not quite as sensitive

Question 25

What is COPD?

Answer 25

Airflow obstruction caused by chronic Bronchitis or emphysema; enlarged (and destroyed) airspaces distal to terminal bronchioles

Question 26

What does emphysema cause?

Answer 26

Elongated lungs (hyperinflation,) flattening of the diaphragm Increased retrosternal clearing, enlarged pulmonary arteries

Question 27

Destruction of bronchioles and/or bullae are two CT findings in what?

Answer 27

COPD

Question 28

Differentiate bulla and blebs. Describe each in detail

Answer 28

1) Bulla are large air-containing lesions in the lung, visible on CXR; > 1 cm Usually associated with emphysema May become infected and contain fluid If completely filled due to infection, these may appear solid CT scan will be able to differentiate from solid tumor 2) Blebs are usually < 1 cm, often not visible on CXR Occur often in the apex Associated with emphysema and spontaneous pneumothorax

Question 29

Lung cysts (pneumatoceles): 1) Where do they occur? What causes them? 2) What do they look like?

Answer 29

1) Occur in the parenchyma Either congenital or infectious 2) Walls are thicker than that of bulla Not typically seen on CXR

Question 30

Cavities: 1) Where do they occur? 2) What causes them? 3) Are they thick or thin?

Answer 30

1) Occur in the parenchyma 2) Usually result from necrotic process 3) Thickest walls of all air containing lesions

Question 31

Bronchiectasis 1) What causes it? 2) Where does it usually occur? 3) What are the Sx? 4) What does it look like on CT?

Answer 31

1) Results from chronic damage to the bronchial tree Localized, irreversible dilatation Usually in the setting of CF or COPD 2) Usually in lower lobes 3) Chronic (often copiously) productive cough and hemoptysis 4) Key word on CXR is “tram-tracks”: Parallel opacity from thickened and dilated bronchial walls

Question 32

Rib fractures: 1) Are they common? Are they deadly? 2) What do they clue you into? 3) Where do they occur?

Answer 32

1) Very common in blunt trauma -Mortality rate increases as the number of rib fractures increase 2) Their presence provides clues to look for underlying visceral abnormalities 3) Uncommon to fracture any of the first 3 ribs, but if they are fractured there will likely be underlying injuries as well

Question 33

Which rib fractures are common and uncommon? Are they always visible?

Answer 33

1) Fractures of ribs 4-9 are common and can cause a pneumothorax if the bone is displaced Fractures of ribs 10-12 are associated with trauma to the liver (right) or spleen (left) 2) In minor trauma, rib fractures may not be visible initially until a callus starts to form after several weeks

Question 34

Subcutaneous Emphysema: 1) What is it? 2) What causes it? 3) Is it serious?

Answer 34

1) Air in the soft tissues (ex/ neck, chest, abdominal wall) 2) From mediastinum - surgical vs traumatic entry into the thorax. Air along muscle bundles usually produces these characteristic “streaks” 3) Typically, no serious clinical effects; air will ultimately reabsorb

Question 35

List the causes of a Pneumothorax and give examples of each

Answer 35

1) Spontaneous: often develop from rupture of an apical, subpleural bleb or bulla. Commonly occur in tall thin men 20-40 yo. 2) Traumatic: blunt or penetrating or complication of line/device placement 3) Diseases that decrease lung compliance: Chronic fibrotic disease 4) Rupture of an alveolus or bronchiole: asthma

Question 36

List and define the 4 types of pneumothorax

Answer 36

1) Primary: occurs in normal lung ex/ spontaneous 2) Secondary: occurs in diseased lung ex/ emphysema 3) Simple: no shift of mediastinal structures 4) Tension: shift of mediastinal structures away from side of pneumothorax; can cause flattening of the hemidiaphragm under the side of tension

Question 37

Describe PA CXRs of pneumothoraxes

Answer 37

1) Displaced pleural line 2) Absent lung markings extending from visceral pleura 3) Enlargement of costophrenic angle – deep sulcus sign is also suggestive in supine pt

Question 38

Describe the pleural line in PTXs

Answer 38

An absence of lung markings peripheral to the visceral pleural line. As the lung collapses, it typically maintains its usual shape

Question 39

Pneumothorax: 1) What may they look like on supine CXR? 2) How are they usually imaged?

Answer 39

1) In a supine CXR, air may collect anteriorly and inferiorly and cause “deep sulcus sign” of the costophrenic sulci 2) Typically imaged by CXR, chest CT, Ultrasound, or Decubitus chest x-rays (affected side up)

Question 40

Most frequent parenchymal complications of blunt chest trauma are?

Answer 40

Pulmonary contusions

Question 41

Pulmonary contusions: 1) Define these 2) Where do they occur? Are there air bronchograms?

Answer 41

1) Seen as hemorrhage in the lung, usually at the point of impact. 2) Peripherally placed. Air bronchograms are usually not present because blood fills the bronchi as well as the airspaces

Question 42

Pulmonary contusion typically resolves within ____ hours as blood quickly reabsorbs

Answer 42

72

Question 43

Pulmonary laceration/ traumatic pneumatocele: What causes it? How long does it last?

Answer 43

From blunt or penetrating trauma; may be masked by a contusion for the first few days after a trauma May take weeks to months to clear

Question 44

Describe recognizing a pulmonary laceration on imaging

Answer 44

1) Their appearance will depend on whether it contains blood and, if so, how much blood fills the laceration. 2) If it is completely filled with blood, it will appear as a solid, usually ovoid mass. 3) If it is completely filled with air, it will appear as an air-containing, cyst-like structure in the lung

Question 45

Pulmonary Interstitial Emphysema. What is it? What are the 2 outcomes?

Answer 45

When the volume in the alveoli increases it can rupture leading to extra-alveolar air. Depending on the location of the alveolus, the air may burst: 1) outward and cause a pneumothorax or 2) can track backward in the lung parenchyma to the mediastinum and up to neck or to the SQ chest wall or both.

Question 46

When the extra-alveolar air is confined to the interstitial network of the lung it = ?

Answer 46

pulmonary interstitial emphysema

Question 47

Pulmonary Interstitial Emphysema: What are some causes? How is it best seen?

Answer 47

1) Increased risk in patients with assisted mechanical ventilation When this finding is noted, it confers high risk for impending pneumothorax Other causes: asthma and barotrauma 2) Often not seen on CXR, best seen on chest CT

Question 48

Pneumomediastinum: What are some causes?

Answer 48

1) Frequently caused by pulmonary interstitial emphysema air tracks backward along the bronchovascular bundles until it enters the mediastinum 2) Can also be caused by perforation of the esophagus or bronchial tree

Question 49

Describe Pneumomediastinum on Imaging

Answer 49

1) Linear, streak-like lucency associated with a thin white line paralleling the left heart border 2) Streaky air outlining the great vessels (aorta, superior vena cava, carotid arteries) 3) Linear streaks of air parallel to the spine in the upper thorax extending into the neck and surrounding the esophagus and trachea 4) Continuous diaphragm sign

Question 50

Pneumopericardium: 1) What causes it? 2) Who is it more common in? When is it rare? 3) What does it look like?

Answer 50

1) Caused by direct penetrating injury to the pericardium Trauma or line/device placement or surgery 2) More common in pediatrics Rare for air in the pleural space to get into the pericardium outside of surgery 3) Pneumopericardium produces a continuous band of lucency that encircles the heart that extends no higher than the root of the great vessels Best viewed with CT

Question 51

Aortic Trauma: 1) What most freq. causes it? 2) Is it dangerous? Explain

Answer 51

1) Most frequently caused by deceleration injuries from MVAs 2) Very high mortality rate especially prior to reaching the hospital. The longer it takes to get treatment, the higher likelihood of death. -Only those with incomplete tears survive to be imaged

Question 52

How do you recognize Aortic Trauma? What are some findings?

Answer 52

1) Nonspecific abnormalities on CXR Need CT or CT-A 2) Findings in surviving patients can be subtle Findings: Aortic intimal flap, Contour or caliber abnormalities, Periaortic or mediastinal hematomas, or Hemopericardium