Ganglioglioma mimicking transmantle focal cortical dysplasia in a two-year old child with intractable epilepsy

Abstract

We report about a two year old girl with onset of severe temporo-parieto-occipital seizures at age of 7 month, retardation of speech development and ataxia. High resolution T2-weigthed MRI identified a hyperintense lesion arising from the ependyma of the right ventricle to the right superior temporal gyrus. In addition, T1-weighted MRI indicated a slightly hyperintense nodular area within this lesion as well as minute calcification. Neuroradiological inspection was highly compatible with a transmantle type of focal cortical dysplasia or cortical tuber (without further lesions of the tuberous sclerosis complex). PET revealed a hypometabolism of the right parieto-occipital lobe. Maximum valproic acid and oxcarbazepin medication were not sufficient to control seizure activity. Temporo-parietal resection of the lesion was performed and histopathologically examined. In contrast to the clinical diagnosis of a transmantle-type focal cortical dysplasia (FCD type IIB according to Palmini et al., 2004), microscopical inspection revealed a ganglioglioma presenting with dysplastic neurons, a neoplastic glial cell population and expression of CD34– immunoreactive satellite clusters (WHO grade I). Proliferation activity was in the range of 1%. Calcification was present and appeared as microscopically small deposits within small capillaries and neuropil. There were no hint for the presence of balloon cells. Seizure activity is controlled after surgery (postoperative time interval is only 4 month yet). Retrospective analysis of MRI data sets were performed, but gave no further hint for a neoplasia. This is an interesting lesion with histopathological hallmarks of a ganglioglioma (WHO grade I) mimicking a transmantle sign typically observed in FCD type IIB. Indeed, recent molecular-pathological studies point to similar signalling pathways operating in both lesions, i.e. the insulin-growth factor receptor cascade activating the tuberin/hamartin complex.