This patient received radiation therapy as part of a treatment for medulloblastoma when he was an adolescent. More than 30 years after this treatment brain imaging shows a diffuse cerebral atrophy as a post radiation treatment effect and a left frontal lobe tumor corresponding to a glioblastoma. 

Although the patient has all the requisites to fit his new tumor as a radiation-induced glioma, the lesion could also represent a de novo tumor. 

Cahan et al ¹ have defined radiation-induced malignancies as those tumors which fulfill the following criteria: 

• tumor in a previously irradiated area
• sufficient latency time between the original and new tumors
• new tumor must have a distinct histology from the original
• no history of disease predisposing to tumor development