Choroid plexus cysts (CPCs) are cysts that occur within choroid plexus of the brain. They are the most common type of intraventricular cyst, occurring in 1% of all pregnancies.
It is believed that many adults have one or more tiny CPCs. The fetal brain may create these cysts as a normal part of development. They are temporary and usually are gone by the 32nd week of pregnancy.
CPCs are a rare cause of intermittent hydrocephalus. This is caused by a blockage of foramina within the ventricular drainage system of the central nervous system (CNS), which can lead to expansion of the ventricles, compressing the brain (the cranial cavity cannot expand to accommodate the increase in fluid volume) and possibly causing damage.
Pathology
The brain contains pockets or spaces called ventricles with a spongy layer of cells and blood vessels called the choroid plexus. This is in the middle of the fetal brain. The choroid plexus has the important function of producing cerebrospinal fluid. The fluid produced by the cells of the choroid plexus fills the ventricles and then flows around the brain and the spinal cord to provide a cushion of fluid around these structures.
CPCs can form within this structure and come from fluid trapped within this spongy layer of cells, much like a soap bubble or a blister. CPCs are often called "soft signs" or fetal ultrasound "markers" because some studies have found a weak association between CPCs and fetal chromosome abnormalities.
Choroid plexus cysts are usually asymptomatic and disappears by 26 to 28 weeks of pregnancy. However, large cysts can cause hydrocephalus. It is not correlated to the presence of Trisomy 21 (Down syndrome). Therefore, genetic counseling is often recommended to provide more information about fetal CPCs, to answer questions and concerns, and to outline available options such as amniocentesis or a blood test from the mother.
Other factors which may have a bearing on the baby's chances of developing chromosome problems include:
- mother's age at the expected date of delivery
- the results of serum screening; XAFP triple testing or quad screening
- evidence of other "fetal findings" seen at the time of the ultrasound that may suggest a chromosome problem