Temporal lobe lesion demonstrating features of dysembryoplastic neuroepithelial tumor and ganglioglioma: a transitional form?

We report an unusual multimodular glioneuronal lesion found in a temporal lobe from a 17-year-old boy with complex partial seizure. Histologically, this lesion was located within the cortex of the middle temporal gyrus and consisted of multinodular foci and the surrounding cortical dysplasia, resembling dysembryoplastic neuroepithelial tumor (DNT). However, it was quite different in the following respects from usual DNT: 1 nodule found in the subpial area consisted entirely of mature atypical neuronal cells separated by a reticulin fiber network connecting to the pia mater and the area around and between the above nodule, whereas another neighboring nodule, which contained many oligodondroglia-like round cells as well as occasional neuronal cells and fibrillary astrocytic cells, showed scattered neuronal cells in the well-differentiated fibrillary astrocytic stroma, the histological features being those of ganglioglioma (GG). We consider that the present case is a good example of the transitional form between DNT and GG. At 25 months following total lesion extirpation, the patient is healthy and free from seizures.