Choroid Plexus Anomalies: Cysts and Papillomas

Abstract The choroid plexus is a vascular convolute consisting of epithelial cells (microglia), fenestrated blood vessels, and stroma within the ventricular system of the brain. It is the main source of cerebrospinal fluid (CSF). Choroid plexus cysts (CPCs) appear as intracranial fluid-filled lesions within the developing choroid plexus of the lateral ventricles, with a prevalence from 0.18% to 3.6%. They are benign, transient findings. The typical ultrasound (US) finding is a round hypoechogenic cyst in the choroid plexus. These are of variable diameter, ranging from 3 mm to 20 mm with a thick echogenic wall. CPCs are typically seen during the second-trimester screening examination. Cysts decrease rapidly in size and mostly disappear before birth. CPCs are associated with an increased likelihood of trisomy 18. When isolated CPCs are detected, the prior risk (maternal age or prior risk assessment) should be the major factor in deciding whether to offer fetal karyotyping. Parents should be reassured about the favorable outcome in CPC. If associated anomalies are seen, a fetal karyotyping should be offered. Choroid plexus papillomas (CPPs) are extremely rare (0.5%–3% of intracranial tumors in children) and usually histologically benign fetal intracranial tumors, arising from the choroid plexus, and classified as primary tumor grade I. The typical US finding is a hyperechoic hypervascularized intraventricular mass. The tumor causes ventriculomegaly or hydrocephaly in approximately 85% of cases. A planned cesarean section is the delivery mode of choice in severe hydrocephaly. Affected children typically become symptomatic during the first year of life with signs of increased intracranial pressure. CPPs can be cured by surgical resection with favorable outcomes (5-year survival rate of up to 100%).