Subependymal heterotopia

This is a 12-years old girl, previously asymptomatic, with a history of fever followed by three episodes of seizures.

The MRI images (Figs. 1-3) show a smooth, nodular area, isointense to grey matter, on all pulse sequences, along the margin of the atrium of the right lateral ventricle. The closest differential diagnosis is a hamartoma of tuberous sclerosis, but this would be irregular with its long axis perpendicular to the ventricular wall and will not be isointense to grey matter.

Comments

[Yamamoto]

This is what we call an "Aunt Minnie". It's so unmistakably obvious on the coronal T2 and there is nothing that is even closely like it, so there is no need for a differential on this one.

Easily missed without seizures in the history and without T2. This is a nice teaching file case for residents.