Although meningiomas are known to be induced by low doses of cranial 
irradiation, such as those given to treat tinea capitis, little experience has 
been reported on the induction of meningiomas by high-dose cranial irradiation. 
The authors describe a series of 10 patients with meningiomas and a previous 
history of high-dose radiation therapy, usually given for a primary brain tumor. 
Of the 10 patients, eight were female, three had multiple meningiomas, and the 
majority had other stigmata of previous radiation therapy. Eight meningiomas 
were examined pathologically and one-half were classified as either aggressive 
or atypical, or were noted to have a high bromodeoxyuridine labeling index. The 
average time from radiation therapy to diagnosis of a meningioma was 24 years 
(range 5 to 40 years), a shorter interval than that previously reported for 
meningiomas induced by lower doses of irradiation. Within this series, patient 
age at irradiation was significantly correlated with tumor latency; individuals 
who were younger at the time of radiation therapy had a shorter time to 
meningioma formation. The latency of meningioma formation is therefore 
influenced by both the radiation dose and the age of the patient at irradiation.