Specific Imaging Findings

Neuroepithelial cysts appear as well-circumscribed, ovoid, nonenhancing masses that follow CSF density/signal intensity. They can be of variable size and occur virtually anywhere, sometimes with a multiloculated appearance. No surrounding hyperintense gliosis is observed on FLAIR images. In the supratentorial compartment, they are usually in the cerebral white matter, with the frontal lobe being the most typical location. Another common location is adjacent to the hippocampus, referred to as a choroidal fissure cyst.

Pertinent Clinical Information

Neuroglial cysts are usually asymptomatic and incidentally noted. Symptomatic ones present in the fourth or fifth decades of life related to their mass effect. Cysts in the posterior fossa have been reported to cause cranial nerve palsies, focal brainstem dysfunction, and hydrocephalus. Supratentorial cysts may rarely cause seizures or focal motor and/or sensory deficits. Small, incidentally detected neuroepithelial cysts require no follow-up; large cysts may warrant serial imaging to ensure the lack of growth.

Differential Diagnosis

Enlarged Perivascular (Virchow–Robin) Space (168)

1. • usually multiple

2. • typically at basal ganglia, white matter of the convexities, and midbrain

3. • may be indistinguishable from neuroepithelial cysts

Neurocysticercosis (167, 194)

1. • often demonstrates a mural nodule (the scolex)

2. • may partially enhance or show surrounding edema

3. • calcification very common

Neurenteric Cyst

1. • hyperintense to CSF on FLAIR, variable density on CT

Lacunar Infarct

1. • characteristic bright rim on FLAIR images corresponding to surrounding gliosis