TY - CHAP M1 - Book, Section TI - Arachnoid Cyst A1 - Bianchi, Diana W. A1 - Crombleholme, Timothy M. A1 - D'Alton, Mary E. A1 - Malone, Fergal D. Y1 - 2015 N1 - T2 - Fetology: Diagnosis and Management of the Fetal Patient, 2e AB - Key PointsArachnoid cysts are rare central nervous system malformations that represent 1% of neonatal intracranial masses.Arachnoid cysts are diagnosed prenatally as a simple, echolucent area within the fetal head and in which no communication with the ventricular system is seen.The main differential diagnosis for a posterior fossa arachnoid cyst is between mega cisterna magna and Dandy–Walker malformation.Most arachnoid cysts remain stable antenatally, but some may cause hydrocephalus by their mass effect as the pregnancy progresses.Management of pregnancy is generally not altered with an arachnoid cyst, unless significant hydrocephalus is present. Careful head imaging in the neonatal period is required to confirm the diagnosis and exclude associated abnormalities.Prognosis depends on the presence of other malformations, parenchymal hemorrhage, rate of cyst growth, and progession of ventriculomegaly.Pediatric management is usually either expectant, for asymptomatic cysts, or open or endoscopic fenestration or obliteration of the cyst if symptomatic. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - obgyn.mhmedical.com/content.aspx?aid=1106396154 ER -