We describe a gentleman diagnosed with a posterior fossa medulloblastoma in 1998, successfully treated with craniospinal radiation therapy (RT) and posterior fossa RT boost, followed by 12 months of adjuvant chemotherapy. Nineteen years later, at the age of 28, the patient presented with multiple cranial neuropathies and was found to have disseminated high-grade glioma with leptomeningeal dissemination. In addition to the salient features of this case, we provide a brief review of RT-induced malignancies and the need for further research regarding surveillance and prevention strategies.