High F-18FDG uptake in a low-grade supratentorial ganglioglioma - A positron emission tomography case report

Purpose: Positron emission tomography (PET) with fluorine-18 fluorodeoxyglu cose (F-18 FDG) is used for the noninvasive monitoring and grading of prima ry brain tumors. Here the FDG uptake is positively correlated with the mali gnant extent of the lesion and thereby negatively correlated with patient s urvival. Little is known about the FDG PET features of primary brain tumors in children, such as mixed neuronal-glial tumors, Methods: The authors describe a 13-year-old boy who had partial complex sei zures since early childhood caused by a brain tumor in the left temporal ro be. Results: Magnetic resonance and computed tomographic examinations yielded u ncharacteristic results: mixed density, marked calcifications, little contr ast enhancement, a nearly absent mass effect, and no edema. The FDG PET sca n revealed a large hypermetabolic tumor, with a tumor: contralateral gray m atter FDG uptake ratio of 1.45, In contrast to this intense hypermetabolism , the pathologic analysis after gross total resection revealed a low-grade ganglioglioma (WHO grade I), which is usually associated with an excellent prognosis, Conclusions: Mixed neuronal-glial tumors such as gangliogliomas must be con sidered in making differential diagnoses by judging hypermetabolic FDG PET scans in young patients with brain tumors in the presence of uncharacterist ic imaging features.