Prenatal diagnosis of a large suprasellar arachnoid cyst

Arachnoid cysts represent 1% of all intracranial lesions and appear on the arachnoid membrane (subarachnoid space). The etiology and pathogenesis of arachnoid cysts remain unclear and in their majority they are asymptomatic. Due to the developmental origin of arachnoid cysts, these formations can be identified on prenatal fetal imaging. In this report we presented a case of an enlarged suprasellar arachnoid cyst detected incidentally during a routine fetal sonographic examination at 33 weeks of gestation. The cyst remained stable in size prenatally and postnatally without compressive symptoms and signs and the patient has been set under expectant management with serial clinical evaluation and serial imaging of the cyst.