First report of a pineal cyst associated with corpus callosum lipoma.

A 37-year-old man with no medical history, apart from a lifelong horizontal diplopia, underwent brain magnetic resonance imaging, which revealed a curvilinear posterior pericallosal lipoma and a pineal cyst. Corpus callosum lipomas, with an incidence of 0.1%-0.5%, do not require neurosurgical treatment, except in rare cases of malformations causing epilepsy. The indications for surgery of pineal cysts, whose incidence is 0.6%, are controversial, except in case of hydrocephalus. In this case, ophthalmologic examination and magnetic resonance imaging were not consistent for a tectal plate compression and the findings were considered incidental. The association of these 2 abnormalities, which has not been described before, might reflect an interrelated embryologic development for pineal gland and midline lipomas, which derive from aberrant mesenchymal primitive meninx.