Primary intracranial germ cell tumors without an isochromosome 12p

Primary intracranial germ cell tumors are the result of the transformation of primordial cells that are unable to migrate to their normal place. These tumors are rare, accounting for less than 5% of all intracranial tumors and less than 3% of childhood neoplasias. In this paper, we have studied cytogenetically two primary intracranial germ cell tumors, a pineal region germinoma, and a mature teratoma in the right lateral ventricle. Neither tumor presented polyploidy or isochromosome 12p, considered to be characteristic of gonadal germ cell tumors. In the five reports in the literature, only one intracranial germ cell tumor presented i(12p). Perhaps i(12p) negative cases characterize a subtype of germ cell tumors.