Glioblastoma arising within a mediastinal mature teratoma

Herein we present the case of a 42-year-old man who presented with an anterior mediastinal mass, which was found to represent a mature teratoma. Within it, there was a secondary somatic malignant glial neoplasm with mitotic activity and necrosis, compatible with glioblastoma. He experienced early local recurrence and lymph node metastasis, but is alive and well 3 1/2 years after diagnosis. Neither the teratoma nor the glioblastoma components had abnormalities of chromosome 12, which may implicate that this teratoma was more closely related to those arising along the midline of infants and children (type I germ cell tumor) than to the typically malignant testicular examples, which often contain mixed germ cell elements (type II germ cell tumor).