A 47-year-old male presented with headache. Magnetic resonance imaging revealed an enhanced mass lesion in the cerebellar vermis and left cerebellar hemisphere and in the cisterna magna. Gross total removal of the tumor was performed. Histological examination demonstrated squamous cell carcinoma in the dermoid cyst. The patient subsequently received localized radiation therapy of total 55 Gy. He has been without tumor recurrence for 6 years since the surgery. We recommend local radiation therapy over 50 Gy following surgery.