Thoracic


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BRONCHOGENIC CYST

Congenital
Budding abnormality of the ventral diverticulum in the primitive foregut.
Usually solitary

Clinical features:
- Usually asymptomatic
- Symptoms due to compression on adjacent structures (size can increase over time) eg dysphagia, respiratory distress, chest pain
- Can get infected - wall can be thickened

Pathology:
- Often have fibrous capsule
- Usually thin wall (exception: oesophageal bronchogenic cyst likely have thick wall)

Location:
- Mediastinum within 5cm of the carina
- Tracheobronchial tree
- In the lung (less common), usually the lower lobes

Radiograph:
- Smooth, well defined
- Lobular or round shape
- Air-fluid level within if got infected and communicates with the airway (fistula)

CT:
- Varying density depending on the content, can appear solid
- Homogeneous
- +/- thin wall, +/- calcification
- Do not enhance

MRI:
- Increased T2
- Variable T1: Contain mucoid material, sometimes blood
- No Gd enhancement

Rx:
- Surgical resection / Needle aspiration if symptomatic / infected

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LYMPHANGIOLEIOMYOMATOSIS (LAM)

Rare, gradual progressive interstitial disease
Female, reproductive age

Clinical features:
- Recurrent pneumothoraces
- (Chylous) pleural effusion

Association:
Tuberous sclerosis

Pathology:
Smooth muscle proliferation around bronchioles

Radiological findings (HRCT)
- Air trapping
- Thin walled cysts of similar sizes, sometimes sizes varies
- with intervening normal lungs
- Chylous pleural effusion
- Pneumothorax: as a result of air trapping

Key:
Female, cysts and intervening normal lungs, chylous pleural effusion and PTX.
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PULMONARY AVM

Congenital abnormality
Abnormal communication between pulmonary artery and pulmonary vein.
Bypasses the pulmonary capillary bed.

Types: (for embolisation planning)
Simple: Single artery, single vein
Complex: Multiple artery, multiple veins

Clinical features:
- Orthodeoxia - worsening hypoxia on erect position due to gravitational shifting of the blood in the AVM
- Cyanosis
- CVA
- Brain abscess (Right to left shunt)
- Asymptomatic

Association:
- Osler-Weber-Rendu disease aka Hereditary Hemorrhagic Telangiectasia (HHT)
-- 50-60% of patient w/ PAVM have HHT
-- 10-15% of patient w/ HHT have PAVM

CXR:
- Mainly in the lower lobes (up to 70%)
- +/- phleboliths
- 'cord-like' band from the AVM opacity towards the hilum => represents the feeding artery & draining vein

CT:
- homogeneously enhanced nodule
- Presence of feeding artery and draining veins (can be multiple)

Angiography:
- Opacification of the pulmonary veins on arterial run

Complication:
- Paradoxical embolism d/t extra-cardiac right to left shunt, eg stroke
- High output heart failure

Rx:
- Coil embolisation for those with complications mentioned above and those with feeding artery > 3mm

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