Fetal Intracranial Cysts and Tumors

Fetal intracranial cysts are fluid collections reported at prenatal ultrasound examination in the context of the cerebral parenchyma or in the ventricular system. They appear as anechoic formations of varying size. The prognosis is determined by the location, the dimensions, and the etiology of the formation itself. Usually choroid plexus cysts, when isolated, have a good outcome and often regress during pregnancy. Arachnoid cysts, cavum vergae, and cavum veli interpositi fluid collections are benign as well, without relevant impact on postnatal life. Paraventricular and germinolytic cysts require a careful evaluation of fetal brain, because of the challenging differential diagnosis with periventricular leukomalacia, which is related to brain hypoxic damage. Intracranial tumors appear as complex masses, causing a remarkable distortion of normal brain architecture. A histological diagnosis is not possible at prenatal ultrasound, and the prognosis is usually poor.