Malignant transformation of oligoastrocytoma: a case report.

We report a case of oligoastrocytoma resembling dysembryoplastic neuroepithelial tumor (DNT) with malignant transformation. A 35-year-old woman presented with headache and generalized convulsion in May 2003. Magnetic resonance imaging (MRI) revealed an extensive left temporal lobe tumor. She underwent partial resection of the tumor under awake surgery, while preserving her language function. The surgical specimen showed that the majority of the tumor was composed of a glioneuronal element. However, there was also an abundant oligoastrocytoma component. Therefore, our first pathological diagnosis was oligoastrocytoma and DNT. She then underwent radiation therapy. The tumor recurred at the left temporal lobe in June 2005. She then underwent open biopsy. The pathological diagnosis was anaplastic oligoastrocytoma with a MIB-1 staining index of 79%. She received PAV (procarvazine, ACNU, and vincristine) chemotherapy, and the tumor subsided transiently. However, she died 3 years after the first operation. Although the histological findings of the first surgical specimen closely resembled those of DNT, radiologic findings and clinical course were different from those of DNT. The authors concluded that this tumor could be a malignant transformation of oligoastrocytoma mimicking DNT, and we wish to give warning that the presence of a glioneuronal component is not an absolute benign hallmark.