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Choroid Plexus Cyst


KEY FACTS

Terminology

  • Choroid plexus cysts (CPCs)

  • Nonneoplastic, noninflammatory cysts

    • Contained within choroid plexus; lined by compressed connective tissue

Imaging

  • General

    • Typically in atria of lateral ventricle

    • Usually small (2-8 mm)

    • Rare: Large cysts (> 2 cm)

    • Usually multiple, often bilateral

  • CT

    • Isodense or slightly hyperdense to CSF

    • Irregular, peripheral Ca++ common in adults

  • MR

    • Isointense or slightly hyperintense compared with CSF on T1WI

    • 2/3 isointense, 1/3 hypointense on FLAIR

    • 60-80% “bright” on DWI

    • Enhancement (ring, nodular, solid) varies from none to strong

Top Differential Diagnoses

  • Ependymal cyst

  • Neurocysticercosis

  • Epidermoid cyst

  • Choroid plexus papilloma (CPP)

    • Purely cystic CPP very rare

Clinical Issues

  • Found at both ends of age spectrum

    • Common in fetus, infants, older adults

    • Less common in children, young adults

  • Clinically silent, discovered incidentally

  • Associations: Aicardi syndrome, trisomy 18

Diagnostic Checklist

  • Most common choroid plexus mass in adults = CPC

Axial graphic shows multiple cystic masses in the choroid plexus glomi
, often seen incidentally on scans of middle-aged and older adults. Most are degenerative xanthogranulomas.

Axial NECT obtained in an elderly adult with minor head trauma and a normal neurological examination shows dense peripheral calcifications
around cystic masses in the atria of both lateral ventricles. This was an incidental finding with no clinical significance.

Axial T1WI C+ FS MR in a 52-year-old man with headaches and no neurological abnormalities shows multiple mixed solid and ring-enhancing cysts in the atria of both lateral ventricles
.

Series of axial MR scans show incidental finding of bilateral choroid plexus cysts in an older patient. Cysts are slightly hyperintense to cerebrospinal fluid on T1- and T2WIs
, typically do not suppress on FLAIR
, and frequently appear very bright on DWI
.

TERMINOLOGY

Abbreviations

  • Choroid plexus cyst (CPC)

  • Choroid plexus xanthogranuloma (CPX)

Definitions

  • Nonneoplastic, noninflammatory cysts of choroid plexus

    • Lined by compressed connective tissue

    • Adult: CPC is common incidental finding on imaging studies in older patients (~ 40% prevalence)

    • Fetus: CPCs seen in 1% of 2nd trimester pregnancies

IMAGING

General Features

  • Best diagnostic clue

    • Older patient with “bright” cysts in choroid plexuses on T2WI

    • Fetus or newborn with large (> 2 mm) choroid plexus cyst(s) on US

  • Location

    • Most common: Atria of lateral ventricles

      • –

        Attached to or within choroid plexus

      • –

        > 2/3 bilateral

    • Less common: 3rd and 4th ventricles

  • Size

    • Variable

      • –

        Usually small (2-8 mm)

      • –

        Often multiple

      • –

        Rare: Large cysts (> 2 cm)

  • Morphology

    • Cystic or nodular/partially cystic mass(es) in choroid plexus glomi

CT Findings

  • NECT

    • Iso-/slightly hyperdense (due to presence of increased protein) to CSF

    • Irregular, peripheral Ca++ in majority of adult cases

  • CECT

    • Varies from none to rim of solid enhancement

MR Findings

  • T1WI

    • Isointense or slightly hyperintense (due to presence of increased protein) compared to CSF

  • T2WI

    • Hyperintense compared to CSF

  • PD/intermediate

    • Hyperintense

  • FLAIR

    • 2/3 isointense, 1/3 hypointense

  • T2* GRE

    • Foci of “blooming” common

      • –

        Ca++ (intracystic hemorrhage rare)

  • DWI

    • 60-80% show high signal on DWI

  • T1WI C+

    • Enhancement varies from none to strong

    • Variable pattern (solid, ring, nodular)

    • Delayed scans may show filling in of contrast within cysts

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