[Two cases of the middle fossa tumor following radiotherapy against retinoblastoma].

Two cases of brain tumors which developed after radiotherapy against retinoblastomas are reported. A 17-year-old girl was admitted with a chief complaint of swelling in her forehead after head injury in July, 1981. At 7 months old her left eye had been enucleated and she had received radiation therapy of 40 Gy to the right eye because of her bilateral retinoblastoma. On admission a CT scan revealed a high density mass with a partial low density area in her right middle fossa. A right frontotemporal craniotomy was performed and the tumor was removed subtotally, which was diagnosed as a malignant fibrous histiocytoma. The second case was a 14-year-old boy, who had received radiotherapy of 39.6 Gy against retinoblastoma of the right eye after enucleation at 2 months old. He had been well for 14 years after the therapy and was admitted to the hospital with complaints of headache, nausea, vomiting and unsteady gait in January 1985. A CT scan demonstrated a large contrast enhancing mass in the righ middle fossa, which was removed subtotally on January 14, 1985. A histological diagnosis of fibroblastic meningioma was made. Each patient developed a secondary brain tumor after radiotherapy against retinoblastoma. Those tumors appear to be radiation induced, although 10 to 15% of the patients who survived retinoblastoma without radiotherapy had been reported to develop secondary nonocular tumors. The patients with retinoblastoma should be followed up carefully after the initial treatment.