Spontaneous resolution of nonimmune hydrops in a fetus with a cystic adenomatoid malformation.

Congenital cystic adenomatoid malformation (CCAM) is a rare pulmonary anomaly. It is a hamartomatous lesion characterized by a cessation of normal bronchiolar maturation, resulting in overgrowth of the terminal bronchioles. There is no preference for sex or location, and usually the lesion is confined to a single lobe. CCAMs have been classified into three subtypes according to the presence of and size of the cysts. Type I lesions have large cysts (2 to 10 cm in diameter), type II have smaller cysts (< 1 cm in diameter), and type III is noncystic. There have been several reports of diminution in size of these lesions and complete regression. However, in those cases fetal hydrops was absent. In the presence of nonimmune hydrops, fetal prognosis is extremely poor without any intervention. There are only two case reports describing fetal survival without intervention when nonimmune hydrops is present. We present a case of survival of a fetus with CCAM and nonimmune hydrops diagnosed at 24 weeks' gestation.