Does increased 18FDG uptake reflect malignant transformation of a low-grade glioma? A diagnostic dilemma.

Benign gliomas of the brain show decreased uptake of 18F fluorodeoxyglucose (FDG) on positron emission tomography (PET). Malignant transformation is usually manifested by an increase of 18FDG uptake. A 45-year-old female has been followed up since 1987 by means of 18FDG-PET for a right hemispheric World Health Organization Grade II oligoastrocytoma. In 1996, increased epileptic activity was accompanied by increased 18FDG uptake within the temporal part of the tumor. After surgery, the epileptic seizures diminished. Histological examination of the resected tumor showed no change in the pathology when compared with the first biopsy. Localized temporal increase of 18FDG uptake was not associated with malignant progression. The decrease of seizure frequency might shed light on a putative connection of hyperglycolysis and epileptic discharges.