Temozolomide induces radiologic pseudoprogression and tumor cell vanishing in oligodendroglioma

Abstract

Enhanced MRI monitoring has shown that many patients with early radiologic findings of progressive lesions after treatment do not have true tumor progression. Radiologic pseudoprogression occurs in one third of all patients with glioblastoma. Classically, these patients present with an increase in contrast-enhancing lesion size within 12 weeks after finishing chemoradiation therapy followed by subsequent improvement or stabilization without any further treatment. In follow-up MRI studies, our 2 patients showed slow and progressive enlargement in T2/FLAIR hyperintensity, one with nodular morphology, with no contrast enhancement. Our findings raise the possibility that TMZ alone without radiotherapy may also result in radiologic pseudoprogression. Reactive and inflammatory changes seen in the surrounding brain could explain this phenomenon. Therefore, we suggest caution regarding aggressive resection in patients with suspected radiologic pseudoprogression.