An immature teratoma arising in the pineal gland in a 27-year-old male
was shown to present an isochromosome 12p as evidenced by cytogenetic
and fluorescence in situ hybridization analysis. As i(12p) is charact
eristic of gonadal germ cell tumors, this case indicates that similar
genetic pathways may operate in gonadal and intracranial teratomas.