[Bevacizumab-Related Hyperintense Lesions on Diffusion-Weighted Imaging at Different Locations in a Patient with Malignant Glioma].

We report the case of a 60-year-old man who first presented with transient difficulty of word recall. Subsequent MRI revealed an invasive brain tumor in the left frontal lobe. The patient underwent open biopsy, and diffuse astrocytoma(WHO grade II)was diagnosed. However, the malignant potential of this tumor was not particularly low because of a few enhancement on preoperative evaluation, and radiation therapy was initially performed. Four months after ending irradiation, temozolomide treatment was introduced for tumor regrowth. After another 2 months, combined chemotherapy with bevacizumab was also started due to tumor enlargement, which was evaluated as malignant transformation to glioblastoma. Two focal lesions with signal hyperintensity on DWI appeared in the frontal and temporal lobes at different locations 3 months after starting bevacizumab. The left temporal lesion subsequently changed to a ring-enhanced tumor, and glioblastoma(WHO grade IV)was finally diagnosed at decompressive surgery. Another frontal lesion, however, continued to maintain a favorable course without any changes in signal despite appearing as similar signal-hyperintense lesions. The temporal hyperintense lesion may undergo malignant transformation into glioblastoma with typical radiological appearance. Recent studies on image changes following bevacizumab treatment have attracted widespread attention, and the clinical significance of such hyperintense lesions has gained attention. This present case was thought to be valuable because of the contradistinctive aspects at the same time, in which the hyperintense lesions of the frontal and temporal lobes seemed to represent antitumor activity or drug refractory effects based on bevacizumab treatment.