A 35-year-old man developed osteosarcoma of the left parietal and occipital 
bones 16 years after radiotherapy for glioma in the right occipital lobe. 
Radiotherapy of the primary neoplasm used 50 Gy administered to a localized 
field through two lateral ports. The secondary neoplasm arose contralateral to 
the primary lesion but within the irradiated field. The tumor had a multilocular 
cyst with considerable intracranial extension, and symptoms of elevated 
intracranial pressure were prominent early in the course. After a short-lived 
initial remission following surgical intervention and chemotherapy, the patient 
deteriorated because of tumor recurrence and died 18 months after the diagnosis. 
Radiation-induced osteosarcoma is a well-known but rare complication of 
radiotherapy for brain neoplasms with a poor prognosis.