Ganglioglioma associated with cerebral cortical dysplasia: an unusual case with extensive leptomeningeal involvement.

Ganglioglioma is a tumor occurring in children and young adults and characterized by a superficial cortical location and biphasic histologic differentiation encompassing neuronal and glial elements. Ganglioglioma may arise anywhere throughout the neuraxis, including the optic nerve, brain stem, pineal gland, cerebellum, cerebrum, and spinal cord; however, the majority of glioneuronal neoplasms involve the temporal lobe. Gangliogliomas may show focal leptomeningeal involvement, but predominant leptomeningeal involvement by gangliogliomas is extremely rare; only 2 cases of ganglioglioma extensively involving the leptomeninges have been reported. In this report, we present an unusual case of a ganglioglioma predominantly present within the leptomeninges of a 15-year-old boy with a history of seizures. Furthermore, the cerebral cortex beneath the tumor showed dysplastic changes. We report a very unusual case of ganglioglioma involving predominantly the cerebral leptomeninges and associated with adjacent cerebral cortical dysplasia. Histologic characteristics and diagnostic pitfalls are discussed.