[An enlarging dysembryoplastic neuroepithelial tumor during a 6-year period: a case report].

A 16-year-old boy who had been found at the age of 9 years to have complex partial seizures was referred to our department by a psychiatrist for evaluation for surgical treatment of epilepsy, in 1994. A diagnosis of multiple cerebral infarction accompanied with arachnoid cyst was made when he was 11 years old, in 1988, by computed tomography (CT) and magnetic resonance imaging (MRI) findings. Results of a neurological examination on admission revealed marked mental and speech retardation. MRI and CT studies demonstrated an enlarged Sylvian fissure and a mass lesion in the left frontal lobe which was enlarged, compared to the findings of MRI in 1988. A left fronto-temporal craniotomy with excision of the frontal lesion was performed. Histological examination revealed cortical dysplasia, multi-nodular pattern, and glioneuronal components, whose findings coincide with criteria for diagnosing dysembryoplastic neuroepithelial tumors. MIB1 antibody immunostaining study revealed no positivity, but immunostaining study for PCNA (proliferation of cell nuclear antigen) revealed from 0 to 6.5% positivity in each nodule. PCNA high positivity was observed in the nodules which were composed of packed oligodendrocyte-like cells. Enlargement in the size of the lesion in our case suggests increased cell proliferation activity during a 6-year period.