Large CPAM at 22 weeks of gestation with improvement over 10 weeks following two courses of betamethasone

(A) Axial ultrasound examination of the fetal chest with color Doppler at 22 weeks of gestation. Thick arrow points to the heart, which is markedly deviated to the right by a large cystic and solid mass. Pulmonary arteries course through the mass. No right lung is noted.
(B) Coronal T2w MRI at 22 weeks of gestation confirms shift of the heart to the right by a high signal lung. The left diaphragm is deviated inferiorly. CVR is 2.3 with trace ascites.
(C) Following two courses of betamethasone, axial ultrasound at 32 weeks of gestation demonstrates decreased shift of the heart (arrow). Right lung tissue is now visible. CVR is now 0.9.
(D,E) Coronal T2w MRI images at 32 weeks of gestation. The mass is smaller; the heart is now near midline with normal position of the diaphragm.