1. Chest p95-103 (Mediastinal masses, Pulmonary arteries, Trauma, Lines/Devices)

Question 1

Superior mediastinal masses (3)

Answer 1

Superior sulcus tumour
- to be a Pancoast tumour, must have Pancoast syndrome (shoulder pain, C8-T2 radicular pain, Horner syndrome)
- Most common to cause Pancoast syndrome is squamous cell lung Ca (or bronchogenic adenocarcinoma).

Question 2

When is a superior sulcus tumour unresectable (4)?

Answer 2

Brachial plexus involvement C8 or higher.
Diaphragm paralysis (infers C3,4,5 involvement).
>50% vertebral body.
Distal nodes or mets.

Question 3

Anterior mediastinal masses (6)

Answer 3

Thymus,
Teratoma (malignant germ cell tumour),
Thyroid Ca (See endocrine),
Thoracic aorta,
Terrible lymphoma (see later in chapter),
Pericardial cyst.

Question 4

Thymus mass causes (4)

Answer 4

Rebound
- Can become 1.5x normal size after stress or chemo and simulate a mass. Can be hot on PET.
Thymic cyst
- Congenital or acquired (thoracotomy, chemo or HIV).
- Unilocular or multilocular.
- T2 bright.
Thymoma
- range: non-invasive thymoma to invasive thymoma to thymic carcinoma.
- Calcification suggests more aggressive.
- Tend to invade into mediastinal fat and surounding structures.
- Average age = 50
- Can ‘drop met’ into pleura and retroperitoneum, abdominal imaging needed.
- Associated with Myasthenia Gravis, Pure Red Cell Aplasia and Hypogammaglobulinaemia.
Thymolipoma
- Fatty mass with interspersed soft tissue

Question 5

Mediastinal germ cell tumour

Answer 5

75% Teratomas:
- Commonest extragonadal germ cell tumour.
- Occur in kids <1yo and adults 20-30s.
- Benign, small malignant transformation risk.
- Mature subtypes equal in men and women. Immature more common in men.
- Mature teratomas associated with Klinefelter syndrome
- Imaging: cystic appearance (90%) and fat. Can have calcifications including teeth.

Question 6

Pericardial cyst

Answer 6

Rare and benign.
Classically right anterior cardiophrenic angle.

Question 7

Middle mediastinal masses (4)

Answer 7

Fibrosing mediastinitis.
Bronchogenic cyst.
Lymphadenopathy (reactive, infection, TB)
Mediastinal Lipomatosis.

Question 8

Fibrosing mediastinitis - definition/cause (3)

Answer 8

Proliferation of fibrous tissue in the mediastinum.
Commonest known cause is histoplasmosis.
Other causes include TB, radiation, sarcoid.

Question 9

Fibrosing mediastinitis - imaging (2)

Answer 9

Soft tissue mass with calcifications.
Infiltrates fat planes.

Question 10

Fibrosing mediastinitis - associations (2)

Answer 10

Known to cause superior vena cava syndrome.
Associated with retroperitoneal fibrosis when idiopathic.

Question 11

Bronchogenic cyst - imaging (3)

Answer 11

Usually within mediastinum (subcarinal space) or less commonly parenchymal.
Subcarinal ones cause obliteration of azygous line on CXR.
Waterish density on CT.

Question 12

Mediastinal lipomatosis - features (2)

Answer 12

Excess unencapsulated fat in the mediastinum.
Causes: iatrogenic steroids, cushings or obesity.

Question 13

Posterior mediastinal masses (2)

Answer 13

Neurogenic (most common):
Bone marrow

Question 14

Neurogenic posterior mediastinal masses (3)

Answer 14

• Schwannomas,
• Neurofibromas,
• Malignant peripheral nerve sheath tumours

Question 15

Bone marrow posterior mediastinal masses (6)

Answer 15

Extramedullary haematopoiesis (EMH) as a response to bone marrow failure to respond to EPO.
Causes:
CML,
Polycythaemia vera,
myelofibrosis,
sickle cell,
thalassaemia

Question 16

Pulmonary embolism - CXR (4)

Answer 16

Watermark sign - regional oligaemia
Fleishner sign - enlarged pulmonary artery
Hamptom’s hump - Peripheral wedge shaped opacity
Pleural effusion - seen in 30% of PEs

Question 17

Acute vs chronic PE (3)

Answer 17

Central vs Peripheral filling defect.
Venous dilation vs shrunken veins with collateral vessels.
Perivenous soft tissue oedema vs calcifications within thrombi & within venous walls.

Question 18

Pulmonary infarct mimics (2)

Answer 18

Pulmonary infarct is a wedge shaped opacity, which resolves slowly, can sometimes cavitate.
Cavitating lesions can raise suspicion for TB or cancer.

Question 19

Pulmonary artery aneurysm - Causes (6)

Answer 19

Iatrogenic (swan ganz catheter) is most common. “Pt in ITU”
Behcets. “Turkish, mouth and genital ulcers”
Chronic PE.
Hughes-stovin syndrome
Rasmussen aneurysm.
Tetralogy of Fallow repair.

Question 20

Hughes-stovin syndrome (2)

Answer 20

Similar to Behcets.
Recurrent thrombophlebitis and pulmonary artery aneurysm formation & rupture.

Question 21

Rasmussen aneurysm (2)

Answer 21

Pulmonary artery pseudoaneurysm secondary to TB.
Involves upper lobes in setting of reactivation TB.

Question 22

Tetralogy of Fallow repair - pulmonary artery aneurysm

Answer 22

Patch aneurysm from RVOT repair.

Question 23

Pulmonary hypertension - definition & types (3)

Answer 23

Pulmonary arterial pressure >25mmHg.
Causes:
Primary (rare, usually young women),
Secondary (most common).

Question 24

Secondary pulmonary HTN - causes (4)

Answer 24

Chronic PE,
Right heart failure/strain,
Lung parenchymal problems (emphysema and fibrosis),
COPD (PA > Aorta have more mortality).

Question 25

Pulmonary HTN - imaging (4)

Answer 25

Big PA (>29mm or >aorta),
Mural calcifications of central pulmonary arteries,
Right ventricular dilatation and hypertrophy,
Centrilobular ground glass nodules.

Question 26

Pulmonary veno-occlusive disease - features

Answer 26

Uncommon cause of pulmonary HTN, due to post capillary vasculature.
PAH + Normal wedge pressure.
Normal wedge pressure differentiates from other post capillary causes, such as:
- left atrial myxoma,
- mitral stenosis,
- pulmonary vein stenosis

Question 27

Diaphragmatic injury - trivia (4)

Answer 27

Left side 3x more common than right (liver = buffer),
Most ruptures are radial, longer than 10cm, posterolateral position.
Collar sign (hourglass sign) - waist like appearance of herniated organ through injured diaphragm
Dependent viscera sign - Absence of interposition of the lungs between the chest wall and upper abdominal organs (Liver on right, stomach on left).

Question 28

Tracheo-bronchial injury - features (3)

Answer 28

Uncommon, usually within 2cm of carina.
Injury close to carina will cause pneumomediastinum rather than pneumothorax.
Tracheal laceration most common at junction between cartilaginous and membranous mediastinum.

Question 29

Macklin effect - features (2)

Answer 29

Commonest cause of pneumomediastinum in trauma.
Alveolar rupture from blunt trauma, air dissects along bronchovascular sheaths into mediastinum

Question 30

Boerhaave syndrome

Answer 30

Ruptured oesophageal wall due to vomiting, resulting in pneumomediastinum/mediastinitis.

Question 31

Flail chest

Answer 31

Defined as 3 or more comminuted rib fractures or >5 adjacent rib fractures.
Paradoxical motion with breathing.

Question 32

Pneumothorax vs tension pneumothorax

Answer 32

Inversion or flattening of the ipsilateral diaphragm suggests tension

Question 33

Malpositioned chest drain (3)

Answer 33

Can be malpositioned into parenchyma, more likely in background lung disease or pleural adhesions.
Blood around tube.
Bronchopleural fistula can occur.

Question 34

Haemothorax

Answer 34

Pleural fluid in trauma is probably blood. Density 35-70HU.

Question 35

Extrapleural haematoma (4)

Answer 35

Injury to chest wall but parietal pleura is still intact (otherwise it’s a haemothorax).
Classic “persistent fluid collection after pleural drain placement”
Buzzword “displaced extrapleural fat”.
Biconvex appearance is more likely arterial, watch for rapid expansion.

Question 36

Pulmonary contusion (4)

Answer 36

Commonest injury from blunt trauma.
Alveolar haemorrhage without alveolar disruption.
Non-segmental ill defined areas of consolidation with sub-pleural sparing.
Should appear within 6hrs and disappear within 72.

Question 37

Pulmonary laceration (3)

Answer 37

Tear in lung, looks like a pneumatocele with gas-fluid level in it.
Can be masked by surrounding haemorrhage early on.
Laceration resolves slowly compared to contusion, can produce nodule or mass persisting for months.

Question 38

Aortic injury (3)

Answer 38

Commonest site is aortic isthmus. Then root, then diaphragm.
Usually obvious on CTA.
Ductus bump (normal variant) can be a mimic.

Question 39

Blunt cardiac injury (2)

Answer 39

Suggested by haemopericardium in setting of trauma.
Correlate with cardiac enzymes and ECG.

Question 40

Fat embolisation syndrome - features (3)

Answer 40

Seen in long bone fractures or IM nail placement.
Fat embolised to lungs, brain and skin (clinical triad of rash, altered mental state and shortness of breath).
Occurs 1-2 days after fracture, better after 1-3 weeks if survive

Question 41

Fat embolisation syndrome - imaging (2)

Answer 41

Lungs have ground glass appearance like pulmonary oedema.
No filling defect like PE.

Question 42

Barotrauma

Answer 42

Positive pressure ventilation can cause alveolar injury, air dissecting into the mediastinum (Causing pneumomediastinum and pneumothorax).
Acute lung injury or COPD have high risk of barotrauma from ventilation.
Pulmonary fibrosis is protective, lungs dont stretch.

Question 43

Central lines - trivia (2)

Answer 43

Abrupt bend at the tip, near the cavo-atrial junction = azygous.
Left side of heart is either arterial or in a duplicated SVC.

Question 44

Hot quadrate sign

Answer 44

Hyperenhancing segment IV of liver, associated with SVC obstruction, consider if central line present.

Question 45

Endotracheal tube positioning (3)

Answer 45

Tip should be 5cm from carina, halfway between carina and clavicles.
Will go up and down with the chin.
Intubation of right main bronchus is common, with left lung collapse.

Question 46

Intra-aortic balloon pump (IABP)

Answer 46

Used in cardiogenic shock for “diastolic augmentation” - provised baclk pressure to help improve perfusion of great vessels of arch

Question 47

Function of IABP

Answer 47

Decreased LV afterload and increased myocardial perfusion.

Question 48

Correct location of IABP

Answer 48

Balloon in proximal descending aorta, just below origin of left SCA.

Question 49

Complications of IABP

Answer 49

Dissection during insertion,
Obstruction of left SCA from malpositioning.