Choroidal fissure cysts, also known as choroid fissure cysts, are benign intracranial cysts occurring within the choroidal fissure. They are therefore a location-based diagnosis rather than a distinct pathological entity.
They are usually asymptomatic and discovered incidentally. Very rarely, they may cause seizures due to mass effect on the temporal lobe 3.
Choroidal fissure cysts may represent either neuroepithelial cysts (including neuroglial or glioependymal cysts) 2,6 or arachnoid cysts, although reports of pathologic confirmation are scant.
They are usually small and range around about 1-2 centimeters in diameter. Occasionally, larger cysts may be seen. The cysts are usually round on axial and coronal images, with a characteristic spindle or ovoid shape paralleling the long axis of the temporal lobe and choroid fissure on sagittal images.
The choroid plexus is medially displaced in the case of cyst of neuroepithelial ventricular origin and laterally displaced in the case of cyst of arachnoid origin from the choroidal fissure (see diagram).
CT scans show a well-delineated homogeneous low density mass with attenuation characteristics similar to CSF. Calcification and contrast enhancement are absent.
MR signal characteristics are similar to CSF on all sequences. The cyst walls are thin. Contrast enhancement, surrounding edema and gliosis are absent.
Treatment and prognosis
They are almost always benign with interval follow up (not required) showing no imaging changes. As such no treatment is required 1.
General imaging differential considerations include
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