A 44-year-old man after combined left temporal low-grade glioma treatment presented with daily multiple series of seizures. MRI demonstrated diffuse cortical swelling in the left frontal lobe with intensive gyral enhancement. PET with [11C]methionine (PET-MET) revealed increased radiotracer uptake strictly confined to the cortical ribbon of the left cerebral hemisphere, which persisted for 3 months. Tumor recurrence was suggested, and biopsy was performed. No evidence of recurrent tumor was found. During a 2-year follow-up, a diffuse gyral enhancement in the left hemisphere has persisted on MRI; PET has shown high [11C]methionine uptake in the left frontal and parietal cortex with gradual positive dynamics.