Prenatal diagnosis of a suprasellar arachnoid cyst with 2- and 3-dimensional sonography and fetal magnetic resonance imaging: difficulties in management and review of the literature.

rachnoid cysts are intra-arachnoid sacs containing cerebrospinal fluid–like liquid and represent 1% of all intracranial masses in neonates.1 Although well reported, the precise etiology and pathogenesis of arachnoid cysts are uncertain. Being developmental in origin, arachnoid cysts can be detected on prenatal screening. Although sonography is used routinely for fetal assessment, it is difficult to account for some of the additional anomalies. We report a rare case of a suprasellar arachnoid cyst detected incidentally during a routine fetal sonographic examination at 24 weeks’ gestation, with prenatal 2and 3-dimensional sonography, fetal and neonatal magnetic resonance imaging (MRI), and postnatal follow-up.