A 12-year-old boy presented with a lymphoplasmacyte-rich (LPR) meningioma in the posterior fossa. The tumor was subtotally removed. Histological examination showed the tumor had invaded the normal brain tissue despite its benign grade in the World Health Organization classification. The Ki-67 staining index using MIB-1 monoclonal antibody was relatively high. (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography revealed high uptake in the tumor. These findings indicate the atypical nature of LPR meningioma.