pseudencephaly

noun
pseud·​en·​ceph·​a·​ly | \ ˌsüd-in-ˈsef-ə-lē How to pronounce pseudencephaly (audio) \
plural pseudencephalies

Medical Definition of pseudencephaly

: a severe congenital malformation characterized by the presence of a vascular tumorous mass in place of the brain and the partial or complete absence of the upper part of the skull