A 45-year-old man presented with a headache. The medical history included a partial thyroidectomy, a colon polypectomy, and stomach tumors (all benign adenomas) 34, 2, and 1 year earlier, respectively. CT showed a space-occupying lesion in the left cerebellar hemisphere with calcification. The mass showed a striated pattern of hyperintensity on T2-weighted images. An FDG-PET scan was performed after the intravenous administration of 250 MBq (6.8 mCi) F-18 FDG. The images of the brain showed a hypermetabolic area in the left cerebellar hemisphere. The whole body images showed no abnormal accumulation other than physiologic uptake. A presumptive diagnosis of Lhermitte-Duclos disease (LDD) was made.