In the present study, an unusual example of malformation in a 9-day-old-girl, in whom an extracerebral ectopic mass with cysts was found in the anterior cranial cavity, is reported. The brain proper was well developed. The mass was connected to the cerebral base and consisted of neuroglial tissue showing various characteristics of differentiation, including cerebellar cortex and monoaminergic neurons. The ectopia may have developed from the mediobasal portion of the embryonic telencephalon.