Metachronous neurohypophysial immature teratoma occurring 10 years after total resection of pineal mature teratoma

An 18-year-old boy presented with an immature neurohypophysial teratoma occ urring 10 years after total resection of a mature pineal teratoma through a n occipital transtentorial approach in 1989. Thorough histological examinat ion had revealed a mature teratoma. He developed panhypopituitarism and dia betes insipidus in 1999. Magnetic resonance imaging revealed a suprasellar tumor occupying the third ventricle. This tumor was totally resected throug h a frontobasal approach. Histological examination revealed an immature ter atoma. This tumor occurred in a different site from the initial tumor and w as considered to be de novo and thus a so-called metachronous germ cell tum or. Patients with completely resected mature teratoma require extended foll ow-up, including periodic magnetic resonance imaging, because of the risk o f such a metachronous germ cell tumor.