Presentation
Incidental finding on MRI of the cervical spine for radicular symptoms. MRI brain for further assessment.
Patient Data
Within the inferior aspect of the fourth ventricle is a mass with very high T2 signal (similar to CSF) and low T1 signal (again, similar to CSF). On FLAIR, the mass does not fully attenuate, and no contrast enhancement is present. Importantly on DWI/ADC, the mass demonstrates restricted diffusion.
Despite its size, the mass does not result in hydrocephalus. It is an isolated abnormality.
The mass within the 4th ventricle (yellow dotted line) is of low T1 signal and high T2 signal, similar to CSF. On FLAIR much of the lesion, especially peripherally (green arrow) does not fully attenuate, and this same area demonstrates high signal on DWI (red arrow).
Case Discussion
Features are characteristic of an epidermoid cyst, albeit in an unusual location - the posterior fossa is a very common location for these lesions, however, they are in most cases in the prepontine and cerebellopontine cisterns.