Choroid plexus cysts are benign and often transient cysts that typically results in-utero from an infolding of the neuroepithelium.
They should not be confused with adult choroid plexus cysts (which are very commonly found at autopsy and likely degenerate), large intraventricular simple cysts (some of which arise from the choroid plexus) or choroid plexus xanthogranulomas 14.
Their estimated occurrence is 1% ( range 0.2-3.5%) of pregnancies 8-10. They are the most common neuroepithelial cysts of the CNS.
The cysts have no epithelial lining, and as such these are not true cysts, but rather spaces within the choroid plexus filled with clear fluid (CSF) and cellular debris material. The size range can vary from a few millimeters to 1-2 centimeters in diameter.
There is a soft association with aneuploidy (therefore sometimes considered as a soft marker), however the vast majority of cases have no associated abnormality. Recognised associations however include :
- 1% if no other abnormality and around 4% if there are other anomalous features
- the increased risk is essentially the same whether there is a single choroid plexus cyst or multiple cysts
- choroid plexus cyst however may be seen in up to 50% of those with trisomy 18
- trisomy 21
- Klinefelter syndrome
- Aicardi syndrome 1
Typically seen at the level of atria involving the lateral ventricles.
They are typically detected around the 2nd trimester and are seen as sonolucent cysts particularly about the lateral ventricles. The size and number of cysts are thought to affect the risk of aneuploidy by some authors 7. The wall may be echogenic (due to surrounding choroid plexus).
Some studies have suggested that the cysts should be at least 2.5 mm in the screening period of 13 to 21 weeks gestation and at least 2 mm from 22 to 38 weeks gestation for accurate diagnosis. This to avoid confusing the surrounding choroid plexus heterogeneity as cysts.
- iso to slightly hyperattenuated on unenhanced CT (compared with CSF)
- peripheral calcification is common
- hyperintense on T2-weighted images, not completely suppressed on FLAIR images and remain hyperintense to CSF, may show restricted diffusion on DWI
Treatment and prognosis
They generally disappear by 26-28 weeks in utero and are of no significance in most cases 1-2. However if one is seen in antenatal imaging it would warrant careful surveillance of the rest of the fetus due to weak associations with karyotypic abnormalities. Choroid plexus cysts are of concern if the cysts are large (> 1 cm) (controversial evidence), bilateral, multiple and associated with structural abnormalities, when the maternal age is equal to or greater than 32 years, or if the maternal serum screening results are abnormal.
Amniocentesis is suggested when there are other abnormalities or when there is a high risk for trisomy 18.
The cysts themselves resolve in the 3rd trimester and are generally not associated with abnormal CNS development. It is usually the associated conditions that are of concern.
- obstructive hydrocephalus: rare but can happen if the cyst is large
- 1. Naeini RM, Yoo JH, Hunter JV. Spectrum of choroid plexus lesions in children. AJR Am J Roentgenol. 2009;192 (1): 32-40. doi:10.2214/AJR.08.1128 - Pubmed citation
- 2. Deroo TR, Harris RD, Sargent SK et-al. Fetal choroid plexus cysts: prevalence, clinical significance, and sonographic appearance. AJR Am J Roentgenol. 1988;151 (6): 1179-81. AJR Am J Roentgenol (abstract) - Pubmed citation
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Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Choroid plexus cysts||✗|
|Choroid plexus (CP) cysts||✗|