A variant of teratoma composed of incompletely differentiated components resembling fetal tissues. Even if the immature component is only a minor element of an otherwise differentiated teratoma, the tumor is still classified as immature. (Adapted from WHO). The disease is central nervous system immature teratoma (MONDO_0003735, a Monarch Disease Ontology id). Also known as: CNS immature teratoma, immature teratoma of CNS, immature teratoma of central nervous system, immature teratoma of the CNS, immature teratoma of the central nervous system.