Dorsal mesencephalic lipoma with inferior collicular hypoplasia: a case report and review of literature.

Intracranial lipomas are rare lesions the pathogenesis of which is still a matter of debate. We report the case of a patient presenting an asymptomatic lipoma located in the quadrigeminal and supra-cerebellar cisterns. The lipoma was associated with hypoplasia of the right inferior colliculus and of the rostral part of the vermis. Analysis of the relationships between neural tube and meninges prompts us to propose that the primary event of this malformation is a defect of the neural anlage which gives rise to both nervous dysplasia and lack of meningeal induction responsible for lipoma development.