Composite ganglioglioma/dysembryoplastic neuroepithelial tumor: a clinicopathologic study of 8 cases.

Ganglioglioma and dysembryoplastic neuroepithelial tumor are both low-grade glioneuronal neoplasms that most commonly occur in association with chronic epilepsy. Rare cases of tumors with composite features of ganglioglioma and dysembryoplastic neuroepithelial tumor have been reported. We retrospectively reviewed the clinicopathologic features of 8 composite tumors (7 were female; median age, 20 years). All patients had chronic epilepsy and had tumors in either the temporal or the frontal lobe. Six patients are currently seizure-free (follow-up: median, 90 months). All tumors were multinodular. Some nodules had distinct features of each tumor type (range, 5%-85% of the tumor). Seven tumors contained nodules with mixed features of both tumor types. Five of 7 evaluable tumors demonstrated adjacent focal cortical dysplasia (Palmini type I). Mitotic activity, vascular proliferation, or necrosis was not observed in any of the tumors. Three tumors demonstrated focal meningeal extension. Composite tumors commonly arise in the temporal lobe in young patients with chronic epilepsy; they appear to behave as a World Health Organization grade I neoplasm. Histologically, these multinodular tumors appear to maintain distinct areas with features of each tumor and foci where the 2 patterns are merged. A subset of composite tumors are associated with adjacent focal cortical dysplasia.