MRI findings in a case of a superficial siderosis associated with an ependymoma.

We present the imaging findings of superficial siderosis of the central nervous system associated with an ependymoma of the posterior fossa in a patient who presented with progressive bilateral sensorineural hearing loss and cerebellar ataxia. The ependymoma was a homogeneous well-defined mass of the fourth ventricle without hydrocephalus. Secondary siderosis due to chronic bleeding from the ependymoma appeared as linear hypointensity delineating the surface of the cortex, thin and subtle on spin-echo T2-weighted images, thick and obvious on gradient-echo T2-weighted images.