Gray matter heterotopia and Lipoma

Findings

The lateral ventricles and 3rd ventricle are slightly increased in size. There is heterotopia along the lateral posterior aspect of the body of the L lateral ventricle. There is a posterior midline fatty lesion consistent with lipoma.


Differential diagnosis for the posterior midline findings:
- Lipoma
- Dermoid or teratoma (Should have more heterogeneity and not be as low in overall density)
- Lipomatous differentiation or transformation of neoplasm or cerebellar lipo- neurocytoma (again, more heterogeneous)

Differential diagnosis for the left lateral ventricle finding:
- Gray matter heterotopia
- Tuberous sclerosis subependymal nodules (frequently calcify and enhance)


Diagnosis: Gray matter heterotopia and Lipoma


Key points

Gray matter heterotopias:
- Are migrational disorders.
- Can result in seizures.
- Associated with many syndromes, most commonly Chiari II and agenesis of the corpus callosum.

CNS lipomas:
- Are congenital malformations and not true neoplasms.
- Are due to maldevelopment of the meninx primitive.
- Often associated with agenesis of the corpus callosum.
- About half are seen in the interhemispheric fissure.
- Many calcify, but rarely in the posterior fossa.