OBJECTIVETo study the clinicopathologic features of brain tumors occurring in patients with medically intractable epilepsy.

METHODSThe clinical, radiologic and pathologic features of brain tumors occurring in 35 patients with intractable epilepsy encountered during the period from January, 2005 to April, 2008 in Xuanwu Hospital were retrospectively reviewed.

RESULTSThe mean age of seizure onset and duration of disease were 14.3-year-old and 8.6 years, respectively. Abnormal signals were observed in 94.3% of cases (33/35) by magnetic resonance imaging. The histologic types of brain tumors included ganglioglioma (13/35, WHO grade I and 6/35, WHO grade II), dysembryoplastic neuroepithelial tumor (3/35, WHO grade I), pleomorphic xanthoastrocytoma (3/35, WHO grade II), diffuse astrocytoma (1/35, WHO grade II), oligoastrocytoma (1/35, WHO grade II), angiocentric glioma (1/35, WHO grade I) and meningioangiomatosis (1/35). The 6 remaining cases showed features seen in between glioneuronal hamartoma and mixed neuronal-glial tumor. Most of these tumors were located in the temporal lobe (27/35) and associated with focal cortical dysplasia. Immunohistochemical study showed a remarkable expression of CD34 in gangliogliomas.

CONCLUSIONSBrain tumors in patients with medically intractable epilepsy are almost always benign and located in the temporal lobe. Most of them represent mixed neuronal-glial tumors and some show transitional features in-between glioneuronal hamartoma and mixed neuronal-glial neoplasm. The similar morphologic pattern and biological behavior of glioneuronal hamartoma and mixed neuronal-glial tumor may suggest a common pathogenetic mechanism.