BT-10 A RARE CASE OF RADIATION-INDUCED GLIOBLASTOMA 29 YEARS AFTER TREATMENTS OF GERMINOMA

BACKGROUND: Germinoma is one of the most radiosensitive tumors. Although radiotherapy (RT) can lead to long term-survival, it has the possibility to cause adverse effects. One of the more serious side effects include radiation-induced tumors that can contribute to a life-long prognosis. CASE PRESENTATION: A 40-year-old man was diagnosed with left basal ganglia germinoma at the age of 11 years old. Postoperatively, he received whole-brain radiotherapy 40Gy, focal radiotherapy 9.26Gy, and craniospinal irradiation. After these treatments, he was free from tumor recurrence or a secondary tumor during the long-term follow up. However, after 29 years, he began experiencing aphasia. A Magnetic Resonance Imaging (MRI) showed a developing 4.5cm round mass in the left parietal lobe with marked surrounding edema. He underwent surgical resection of the tumor at the left partial lobe. Pathological examination showed the tumor to consist of unclear pleomorphism, and the diffuse proliferation of heterocyst. Therefore, the pathologic diagnoses concluded as glioblastoma (Ki-67 labeling index was 50%). Conclusion: The tumor developed in the previously irradiated field, and it was not present prior to the RT. He did not suffer from pathologies favoring the development of the tumor. The interval between the radiation exposure and the onset of the second tumor was approximately 29 years, and the histotype of the tumor differed from the original tumor. Considering these clinical features, we diagnosed the glioblastoma as a radiation-induced tumor. Radiation-induced malignant glioma occurs frequently in patients after the treatment for acute lymphoblastic leukemia. Therefore, the radiation-induced malignant glioma after the treatment for germinoma is rare. Regardless of age, histology, and RT dosages, the patient has the possibility to develop radiation-induced malignant glioma. In conclusion, it is necessary to have careful monitoring even after 20–30 years of RT.