Disappearing suprarenal masses in fetuses and infants.

This paper presents 12 infants (9 boys, 3 girls) in whom the diagnosis of a suprarenal mass (10 left, 2 bilateral) was made on antenatal sonography. All were otherwise healthy neonates who were born at term after a normal pregnancy, labor and delivery. The masses ranged from 1 to 3.5 cm in diameter on initial scans at gestational ages of 19-35 weeks. Eleven masses were hyperechoic and 4 of these contained small, well-defined cysts. The 12th was hypoechoic. Follow-up sonography showed complete disappearance of the mass antenatally in 1 case and postnatally by 4-6 months in 5 cases; there was marked diminution in the size of the mass by 2 months of age in 4 infants, by 4 months in 1 case and by 15 months in 1 case. Eleven were managed nonoperatively. Laparotomy (after disappearance of the mass) in the 12th case revealed only some fibrous tissue. The 11 echogenic masses resemble previously reported imaging findings in infants with histologically proven intra-abdominal sequestrated lung. Conservative management with careful sonographic follow-up should, therefore, be considered in otherwise healthy fetuses or neonates with these imaging findings. We are less certain what the hypoechoic mass represented.