SPR Unknown # 89 -- FINAL

Kimberly Dannull, MD

Children's Hospital Colorado


Publication Date: 2013-06-06

History

Prenatal screening ultrasound abnormality in a dichorionic diamniotic twin pregnancy.

Findings

Large multilocular cystic mass fills and expands the right hemithorax with inferior displacement/eversion of the right hemidiaphragm and leftward deviation of the heart and great vessels. There is extension of the mass anteriorly across midline. This mass contains multiple variable sized cysts with thin intervening septa, with the largest cyst measuring 3.3 cm. No feeding artery was identified off the aorta. Resultant fetal hydrops is noted secondary to mass effect upon cardiovascular structures, with marked scalp edema, moderate subcutaneous edema of the chest wall and moderate ascites.

Diagnosis

Congenital pulmonary airway malformation (CPAM), Type 1

Differential

Congenital diaphragmatic hernia (CDH)

Bronchopulmonary sequestration (BPS)

Hybrid lesion (CPAM with BPS)

Congenital lobar overinflation (CLO)

Mediastinal lymphatic malformation

Predominantly cystic teratoma

Files

Discussion

The differential diagnosis for a fetal chest lesion includes the bronchopulmonary malformation spectrum: congenital pulmonary airway malformations (CPAM), bronchopulmonary sequestration (BPS), hybrid lesions (CPAM and sequestration combined) and congenital lobar overinflation (CLO) all of which appear hyperintense on T2 weighted images. Congenital diaphragmatic hernia and teratoma are occasionally seen, however are heterogeneous on T2 weighted images, and have imaging features which more readily distinguish them from the above lesions on MRI. Of the bronchopulmonary malformations, the most common are CPAM lesions which comprise approximately half of the spectrum. There are 5 types of CPAM lesions (Stocker classification), the most common is type 1 (macrocystic). Overall, type 1 CPAM lesions are associated with a favorable prognosis. However, some can grow in utero, particularly in the late second/early third trimester, with the substantial mass effect causing hydrops which is reported to occur in approximately 5% of lesions.

In utero treatment of CPAM lesions is varied and includes amnioreduction for polyhydramnios, serial thoracentesis and bethamethasone. With a large dominant cyst, a thoracoamniotic shunt can be placed. In the current case there were multiple cysts with intervening septa requiring additional septal ablation at the time of shunt placement. The substantial hydrops which was present on initial presentation resolved after shunt placement and the baby is currently doing well, with only mild pulmonary hypertension clinically.

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