RESUMEN
A 60-year-old female patient was treated with gamma knife on the left frontal lobe metastatic brain tumor. After 3 months, the tumor and peri-focal edema turned worse due to radiation necrosis. Despite increasing doses of steroid administration, the deterioration lasted for 6 months. The symptoms and brain edema did not improve for over a year, but we decided to observe the patient without bevacizumab. We performed Methionine-PET to diagnose radiation necrosis of the brain, and confirmed absence of hot spots. The steroid therapy continued and added saireito 9 g/day, because we thought brain edema was concerned with fluid retention. After 9 months, head MRI showed improvements of the brain edema. Saireito may help improve brain edema due to radiation necrosis.