Evaluation of pleomorphic xanthoastrocytoma by use of positron emission tomography with

Abstract

We present a case of pleomorphic xanthoastrocytoma (PXA) in a patient with temporal lobe seizures. Imaging sequences included MR, and results of positron emission tomography (PET) with [18F]-fluorodeoxyglucose (FDG) and [11C]-methionine (Met) tracers revealed a hypermetabolic region equivalent or nearly equivalent to normal cerebral cortex, suggesting that the tumor might have malignant potential. Histopathologic findings indicated low-grade glioma. The mechanism for glucose hypermetabolic activity of PXA is not clear; however, the positive findings obtained from FDG-PET may not always indicate the degree of malignancy associated with PXA.

fig 1.

A, Axial postcontrast (Gd-DTPA) T1-weighted MR image shows a cystic lesion in the left temporal lobe. A poorly enhanced area is visualized at the anterior portion of the cyst (arrow head). B, Axial T2-weighted MR image shows a slightly hyperintense lesion around the cystic lesion appearing as areas of high signal intensity. C, FLAIR image shows a well-demarcated high-signal area around the cystic lesion.

fig 2.

A, Axial FDG-PET image shows uptake of tracer in the lesion that is difficult to distinguish from cerebral cortex (arrow heads). The region of increased activity, which corresponds to the tumor, is in the left temporal lobe. B, Axial Met-PET image depicts high uptake of tracer in the lesion. The area of increased accumulation of Met is larger than that of FDG.

fig 3.

Photomicrograph of a tissue section (hematoxylin and eosin stain ×100) The section shows a moderately cellular glial neoplasm composed of giant astrocytes with pleomorphic nuclei in the area of cellular pleomorphism (arrow heads). There is no mitotic activity and no necrosis