KEY FACTS
Imaging
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Variable appearance from solid-appearing (microcystic) to complex cystic mass (macrocystic)
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Macrocystic : 1 or more cysts ≥ 5 mm
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May have single large cyst
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Microcystic : Cysts < 5 mm (appears homogeneously echogenic)
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No side predilection, more common at lung bases
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Vascular supply from pulmonary artery
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Monitor frequently for hydrops
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Ascites, from mediastinal compression, may be 1st sign
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Follow closely until growth stabilizes
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Top Differential Diagnoses
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Bronchopulmonary sequestration
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Should see obvious feeding vessel from aorta
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Congenital diaphragmatic hernia
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Dilated bowel loops can appear like macrocystic CPAM
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Clinical Issues
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Stable lesions may be watched without intervention
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Often decrease in size or completely regress (“disappearing” CPAM)
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Microcystic CPAMs often stabilize and begin regressing at 26-28 weeks but are more prone to cause hydrops
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Macrocystic CPAM may grow throughout pregnancy
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Hydrops significantly impacts prognosis
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Near 100% mortality with hydrops if untreated
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Mortality has declined significantly with steroid administration
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Scanning Tips
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Ensure diaphragm intact, ruling out diaphragmatic hernia
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Color Doppler evaluation essential for any chest mass to look for source of feeding vessel
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Look carefully for signs of developing hydrops
shows a large, uniformly echogenic lung mass 
having mass effect with shift of the heart 
to the right. The primary differential is a microcystic CPAM vs. a sequestration, so the next step is evaluation of the blood supply.
from the pulmonary artery, not the aorta 
, confirming that this is a CPAM.
. More importantly, there is ascites 
. Developing hydrops portends a very poor prognosis, so the patient was treated with steroids.Related posts:
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