Midline cystic mass in fetal brain

A teratoma is a tumor made up of several different types of tissue, such as hair, muscle, teeth, or bone. Teratoma typically form in the ovary, testicle, or coccyx. [Source: Wikipedia ]

Synonyms
Midline cystic fetal brain mass
May Be Caused by
 Common
Agenesis of the corpus callosum
Dandy-Walker malformation
Holoprosencephaly
Vein of Galen aneurysm
 Uncommon
Arachnoid cyst
Cystic neoplasm