Abstracts

Rationale: Many developmental tumors are benign glioneuronal tumors, such as ganglioglioma and desmoplastic neuroepithelial tumors. Patients with developmental tumours are complicated with chronic epilepsy at high incidence, although tumors rarely progress or cause in neurologic dysfunction. It is also well known that focal cortical dysplasias (FCDs) occasionally coexist with other brain lesions usually in adjacent to or affecting to the same cortical area or lobe. According to ILAE classification of FCDs, FCDs coexist with tumors are called FCD type IIIb and their pathological hallmark are disorganized cytoarchitecture often with abnormal neurons. Although the pathogenesis of the FCD type IIIb is unknown, it is thought to be a result of acquired process. We report a unusual case of ganglioglioma with focal cortical dysplasia type IIb. Methods: A 1-month-old male infant presented with frequent and clonic seizure of the right limbs. Computed tomography of the brain revealed a single tuberous calcified region in the left frontal lobe. Medial treatment improved his epileptic attacks transiently, and At 13 months of age, he was admitted to the hospital for further evaluation. and exhibited delayed developmental achievements. A general examination showed no signs of tuberous sclerosis complex (TSC). Magnetic resonance imaging (MRI) of the brain showed a normointense lesion with a hypointense rim on T2-weighted image (T2WI). Adjacent to the lesion, there were thick gyri with subcortical hyperintensity on T2WI. At 15 months, he underwent surgical resection of the lesion. Postoperative course was good without recurrence of seizure. Pathological investigation and DNA analysis of the patient's resected brain tissues and blood were performed under informed consent. Results: Microscopic examination of the resected tissues revealed clusters of large ganglion cells with massive proliferation of neurofilament-positive astrocytes. Calcification was also observed in the lesion, especially in the center. Based on the pathological features, we diagnosed the patient as ganglioglioma. The cortical lesions adjacent to the tumor showed a disorganized pattern with balloon cells and dysmorphic neurons. Balloon cells express phosphorylated S6 protein and nestin but minimal glial fibrillary acidic protein. These findings were considered compatible with FCD type IIB. Gene analyses of TSC1and TSC2 revealed no mutations. Conclusions: There are very few reports of patients with both FCD and glioneuronal tumors. Prayson at al (2010) reported that 40 out of 270 epileptogenic tumor specimens had coexistant FCDs and FCD type II was observed only in 3 cases. It is well known that both conditions belong to the same pathological category as hamartoma. There is a possibility that the tumor and FCD is coexisting incidentally, but the present case suggests a common pathogenesis of FCDs and benign glioneuronal tumors.