Increased expression of L-amino acid transporters in balloon cells of tuberous sclerosis.

OBJECTS: Tuberous sclerosis complex (TSC) is a dysgenetic syndrome involved in multiple organs, and the pathognomonic cortical tuber act as an epileptic substrate. The amino acid transport system L (LAT) is a major nutrient transport system, and LAT1 is highly expressed in malignant tumors to support tumor cell growth. To study the life-long epilepsy from the cortical tuber, the expression of LAT1 in balloon cells and dysplastic neurons of the cortical tuber is investigated. MATERIALS AND METHODS: LAT1 expression was investigated by LAT1 mRNA using reverse transcription-polymerase chain reaction and immunohistochemical staining with anti-human LAT1 antibody in nine patients with TSC and three control brains. CONCLUSION: LAT1 mRNA was detectable only in fresh-frozen tissues of TSC, and it was upregulated in the cortical tuber lesion. While the LAT1 immunopositivity of control brains was limited in the capillary endothelial cells in the gray matter, increased LAT1 immunopositivity was noted in balloon cells of the cortical tubers in addition to the capillary endothelial cells as shown in control brains. Linear and strong immunopositivity along the cell membrane and cytoplasm of the balloon cells, and weakly granular immunopositivity in their cytoplasm were noted. Increased expression of LAT1 in the balloon cells is important for the active transport of large neutral amino acids into the balloon cells, and that the biologic process may play an important role in the active protein synthesis with metabolic maintenance of balloon cells in cortical tubers of patients with TSC.

Clinical features and epileptogenesis of dysembryoplastic neuroepithelial tumor.

INTRODUCTION: Dysembryoplastic neuroepithelial tumor (DNT) frequently causes medically intractable epilepsy. OBJECTIVE: The aim of this study was to investigate the basic mechanism of epileptogenecity of the tumor. MATERIALS AND METHODS: Clinicopathological data in 13 cases of DNT and immunohistochemical changes of ionotropic glutamate receptor subunits in the tumor and peritumoral epileptogenic cortex were studied. CONCLUSIONS: Magnetic resonance imaging combined with electroencephalography (EEG), electrocorticography, and depth-electrode EEG was valuable to localize complicated epileptogenic zones of the patients with DNT. Neuropathological examinations of the peritumoral cerebral cortex presenting abnormal spikes showed different histopathological grades of neuronal migration disorder (NMD). The tumor cells in DNT disclosed increased immunopositivities of N-methyl-D: -aspartate receptor 1 (NR1) and NR2A/B, and peritumoral epileptogenic NMD revealed increased immunopositivities of GluR2 and GluR3. The amplification of ionotropic glutamate receptor subunits in the tumor and peritumoral NMD may be the underlying cause of epileptic seizures in DNT patients.

Atypical teratoid/rhabdoid tumor of the central nervous system: clinico-pathological study.

Atypical teratoid/rhabdoid tumor (AT/RT) is a new entity among malignant pediatric brain tumors. This study was performed to investigate the clinicopathologic and cytogenetic features of the tumor. Five cases from a series of the brain tumors were studied. Clinical features of the patients were assessed with age, sex, location of the tumors, treatments and survival periods. Histopathologic features were analyzed by routine HE stain and immunohistochemical stains for epithelial membrane antigen, cytokeratin, vimentin, smooth muscle actin, desmin, GFAP, S-100 protein, neurofilament protein, synaptophysin and alpha-feto protein. Cytogenetic studies for karyotype analysis and fluorescent in situ hybridization were available in three cases. Mean age of patients was 5.6 years, and maximal survival periods were less than 13 months despite surgical and radiation therapy. The tumors were located in infratentorial and supratentorial areas. Histopathologically, the tumors were chiefly composed of rhabdoid cells, modified rhabdoid cells and undifferentiated small cells, mixed with epithelial, mesenchymal, and neural tumor-like areas. These polyphenotypic features of the tumor cells were supported by diverse immunoreaction. Monosomy of chromosome 22 was demonstrated in two cases of the tumor. These results suggest that AT/RT may be a unique clinicopathologic entity, and histopathologic diagnosis of it should be made judiciously by differentiating other polymorphous tumors of the brain.