[Radiation-induced leiomyosarcoma of the dura mater: a case report].

A 31-year-old man underwent total resection for a fibrillary astrocytoma in the right frontal lobe followed by 6MV x-ray radiotherapy. The portal field size was a square of 8 cm x 7 cm, and the total dose of irradiation was 50Gy, with single fractions of 2Gy. For the next 6.5 years there was no recurrence of the astrocytoma. At 38 years of age, the patient noticed a subcutaneous mass in the scar of the previous operation and developed generalized convulsive seizures. MRI revealed a dural tumor within the previous radiation field, and the tumor was partially removed. Histologically, it was diagnosed as a leiomyosarcoma. This dural sarcoma satisfies the widely used criteria for definition of radiation-induced malignancies first described by Cahan et al. Both the clinical features and the possible histogenesis of this secondary tumor are briefly discussed.