KEY FACTS
Terminology
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Bronchopulmonary tissue that does not connect to tracheobronchial tree or pulmonary arteries
Imaging
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Homogeneously echogenic lesion adjacent to diaphragm
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Typically triangular and well defined but can fill hemithorax and be difficult to differentiate from compressed lung
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Color Doppler key: Prominent feeding vessel from aorta
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85-90% in chest; 90% left sided
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10-15% subdiaphragmatic
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Stomach is displaced anteriorly by echogenic mass
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Separate from adrenal gland
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Has prominent feeding vessel from aorta just like those in chest
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Unilateral pleural effusion (same side as BPS) in 6-10%
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May cause tension hydrothorax shifting heart and compressing mediastinal structures
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Top Differential Diagnoses
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Congenital pulmonary airway malformation (CPAM)
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Microcystic (echogenic) CPAM has similar appearance
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Vascular supply from pulmonary arteries, not aorta
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Neuroblastoma: Most common differential consideration for subdiaphragmatic sequestration
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More often on right
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Often cystic with no feeding vessel
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Clinical Issues
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10-20% of fetal lung masses
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Associated anomalies reported in up to 50%
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Most commonly associated with congenital diaphragmatic hernia but is often missed
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Excellent prognosis when isolated finding
Scanning Tips
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Use color Doppler on every chest mass looking for blood supply
is from the aorta 
. It is sequestered from the surrounding lung, and there is no communication with the tracheobronchial tree.
. A large feeding vessel is seen coming from the aorta 
. A tracing from this vessel (below) shows the classic aortic waveform with a sharp, rapid upstroke.
