Choroid plexus cyst explained

Choroid plexus cyst
Field:	Neurosurgery

Choroid plexus cysts (CPCs) are cysts that occur within choroid plexus of the brain. They are the most common type of intraventricular cyst,^[1] occurring in 1% of all pregnancies.^[2]

It is believed that many adults have one or more tiny CPCs.^[3] 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.^[4]

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.^[5]

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.^[2]

Genetic causes

There is a possible association between ultrasound-detected fetal CPCs and Trisomy 18.^{[6] [7]} It is not correlated to the presence of Trisomy 21 (Down syndrome).^{[8] [9]} 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.^[6]

Generally the risks are very low if there are no other risk factors. If no additional abnormalities are detected by a thorough "level II" ultrasound, the likelihood the fetus has trisomy 18 is very low.

A meta-analysis of 8 studies between 1990 and 2000 with choroid plexus cysts that were identified in second-trimester (an incidence of 1.2%). The incidence of the cysts in women younger than 35 was 1% (n=1017). The study found no cases of trisomy 18 in fetuses with cysts whose mother was younger than 35. The study concluded that "there is no evidence that detection of isolated choroid plexus cyst in women who are <35 years of age increases the risk of trisomy 18".^[10]

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

Further reading

• Lun . Melody P. . Monuki . Edwin S. . Lehtinen . Maria K. . Development and functions of the choroid plexus–cerebrospinal fluid system . Nature Reviews Neuroscience . 2015 . 16 . 8 . 445–457 . 10.1038/nrn3921 . 26174708 . 4629451 .
• Rochon . Meredith . Eddleman . Keith . Controversial ultrasound findings . Obstetrics and Gynecology Clinics of North America . March 2004 . 31 . 1 . 61–99 . 10.1016/S0889-8545(03)00123-2 . 15062448 .
• Book: McKinney . Alexander M. . Atlas of Normal Imaging Variations of the Brain, Skull, and Craniocervical Vasculature . 2017 . Springer International Publishing . 978-3-319-39790-0 . 177–237 . 10.1007/978-3-319-39790-0_11 . Choroid Plexus: Normal Locations and Appearances .
• Aktürk . Erhan . Güler . Aşkın Evren . Review of fetal choroid plexus cysts: A cross-sectional study on 9244 pregnant women . Journal of Surgery and Medicine . 26 March 2020 . 10.28982/josam.706887 . free .
• DeRoo . TR . Harris . RD . Sargent . SK . Denholm . TA . Crow . HC . Fetal choroid plexus cysts: prevalence, clinical significance, and sonographic appearance . American Journal of Roentgenology . December 1988 . 151 . 6 . 1179–1181 . 10.2214/ajr.151.6.1179 . 3055893 .
• Chitkara . Usha . Cogswell . Carolyn . Norton . Karen . Wilkins . Isabelle A. . Mehalek . Karen . Berkowitz . Richard L. . Choroid Plexus Cysts in the Fetus: A Benign Anatomic Variant or Pathologic Entity? Report of 41 Cases and Review of the Literature . Obstetrics & Gynecology . August 1988 . 72 . 2 . 185–189 . 3292976 .

Notes and References

1. Pappalardo . Elisa Maria . Militello . Mariapia . Rapisarda . Giusi . Imbruglia . Laura . Recupero . Stefania . Ermito . Santina . Dinatale . Angela . Carrara . Sabina . Cavaliere . Alessandro . Fetal intracranial cysts: prenatal diagnosis and outcome . Journal of Prenatal Medicine . 2009 . 3 . 2 . 28–30 . 22439038 . 3279101 .
2. Naeini RM, Yoo JH, Hunter JV . Spectrum of choroid plexus lesions in children . AJR. American Journal of Roentgenology . 192 . 1 . 32–40 . January 2009 . 19098176 . 10.2214/ajr.08.1128 .
3. Jeon . Jin Ho . Lee . Sang Weon . Ko . Jun Kyeong . Choi . Byeong Gwan . Cha . Seung Heon . Song . Geun Seong . Choi . Chang Hwa . Neuroendoscopic Removal of Large Choroid Plexus Cyst: A Case Report . Journal of Korean Medical Science . 2005 . 20 . 2 . 335–9 . 10.3346/jkms.2005.20.2.335 . 15832013 . 2808618 .
4. Benacerraf . Beryl R. . Laboda . Lane A. . Cyst of the fetal choroid plexus: A normal variant? . American Journal of Obstetrics and Gynecology . February 1989 . 160 . 2 . 319–321 . 10.1016/0002-9378(89)90434-1 . 2644832 . 21224368 .
5. Büttner . A. . Winkler . P. A. . Eisenmenger . W. . Weis . S. . 41162320 . Colloid cysts of the third ventricle with fatal outcome: a report of two cases and review of the literature . International Journal of Legal Medicine . 10 August 1997 . 110 . 5 . 260–266 . 10.1007/s004140050082 . 9297582 .
6. Hurt . K . Sottner . O . Záhumenský . J . Halaska . M . Krcmár . M . Driák . D . Zmrhalová . B . Rakovicová . I . Cysty chorioidálního plexu a riziko trizomie 18. Modifikace ke vztahu k věku a markerům . Choroid plexus cysts and risk of trisomy 18. Modifications regarding maternal age and markers . Czech . Česká Gynekologie . January 2007 . 72 . 1 . 49–52 . 17357350 .
7. Papp . Csaba . Ban . Zoltan . Szigeti . Zsanett . Csaba . Akos . Beke . Artur . Papp . Zoltan . Role of second trimester sonography in detecting trisomy 18: A review of 70 cases . Journal of Clinical Ultrasound . February 2007 . 35 . 2 . 68–72 . 10.1002/jcu.20290 . 17206726 . 23836946 .
8. Dagklis . T. . Plasencia . W. . Maiz . N. . Duarte . L. . Nicolaides . K. H. . Choroid plexus cyst, intracardiac echogenic focus, hyperechogenic bowel and hydronephrosis in screening for trisomy 21 at 11 + 0 to 13 + 6 weeks . Ultrasound in Obstetrics & Gynecology . February 2008 . 31 . 2 . 132–135 . 10.1002/uog.5224 . 18085527 . free .
9. Bromley . B. . Lieberman . E. . Benacerraf . B. R. . Choroid plexus cysts: not associated with Down syndrome . Ultrasound in Obstetrics and Gynecology . 1 October 1996 . 8 . 4 . 232–235 . 10.1046/j.1469-0705.1996.08040232.x . 8916374 . 10202905 .
10. Demasio . Kafui . Canterino . Joseph . Ananth . Cande . Fernandez . Carlos . Smulian . John . Vintzileos . Anthony . Isolated choroid plexus cyst in low-risk women less than 35 years old . American Journal of Obstetrics and Gynecology . November 2002 . 187 . 5 . 1246–1249 . 10.1067/mob.[phone] . 12439513 .