What?

Ependymitis granularis is characterized by symmetrical foci of periventricular T2 and FLAIR hyperintensity anterior and lateral to the frontal horns of the lateral ventricles.

The foci are usually small - less than 1 cm - and have a triangular morphology extending laterally from the callosal genu.

Why?

It is thought to occur secondary to a focal breakdown of the ependymal lining with adjacent astrocytic gliosis; and into this region periependymal CSF/fluid preferentially drains.

Is it important?

Well no. Despite its name giving the sound of something that is inflammatory, and a 1926 article that claimed it as a cause of chronic internal hydrocephalus, it is now thought to be an anatomical variant of no clinical consequence ^1,2.