Diffuse-Type Tenosynovial Giant Cell Tumor Arising in the Temporomandibular Joint Extending to the External Auditory Canal: A Case Report and Literature Review.

A 74-year-old Japanese woman with a 1-year history of right preauricular pain and a 2-month history of bleeding from the right ear was admitted to our department. Tumor was observed in the anterior wall in the right external auditory canal. Bony swelling of the right preauricular area was palpated. Computed tomography revealed an ill-defined, osteogenic tumor around the mandibular condyle with a destructive bony lesion involving the temporal bone. Magnetic resonance imaging revealed a 2.0 × 1.5 × 1.3-cm solid tumor around the mandibular condyle, exhibiting a low-intensity signal on T1-weighted imaging and an isointense central area surrounded by low-signal intensity on T2-weighted imaging. Histological examination of biopsy specimens revealed diffuse-type tenosynovial giant cell tumor (D-TGCT). After the feeding arteries for the tumor were embolized, the patient underwent surgery with combined temporal craniotomy and mandibular condylectomy. The soft and cystic tumor with calcification located in the extradural space was totally resected along with the mandibular condyle. No facial paralysis or recurrence was evident as of 6 months postoperatively. To date, only 23 cases of D-TGCT arising in the temporomandibular joint (TMJ) with ear involvement have been reported since 2011. We report successful resection of a rare case of D-TGCT arising in the TMJ.

[A supratentorial primitive neuroectodermal tumor exhibiting pathological characteristics of medulloepithelioma: a case report].

A 50-year-old female presented with headache symptoms and left hemifacial paresis. Brain computed tomography and magnetic resonance images demonstrated a right frontal lobe tumor with hemorrhage and calcification. A gross total resection was carried out. Pathologically, the tumor exhibited three kinds of structures. The first was an astrocytic area which occupied the large part of this tumor. Small, round cells, which were positive for glial fibrillary acidic protein, were randomly distributed. The second was an epithelioid area with the highest MIB-1 labeling index of the three structures. Undifferentiated tumor cells demonstrated a dense proliferation, and short spindle-shaped cells exhibited an epithelial and a partly luminal alignment that resembled the embryonal neural tube. The third was a sarcomatoid area. Long spindle-shaped cells, which were positive for vimentin, were in a bundle-like form. We diagnosed this tumor as a primitive neuroectodermal tumor (PNET) with epithelial differentiation. PNETs are rare brain tumors with a predominance in children. Histologically, undifferentiated tumor cells demonstrate dense proliferations. The tumor arises from germinal matrix cells that differentiate into neuronal, glial, and ependymal cells. Medulloepithelioma, which is classified in the PNET category, is a very rare brain tumor that usually develops in childhood. Pathological studies have demonstrated that papillary, tubular, or trabecular arrangements of neoplastic neuroepithelium mimic the embryonic neural tube predominantly. In our case, the tumor partly demonstrated epithelial differentiation, which is a feature of medulloepithelioma, not only glial and mesenchymal differentiation. This is a rare case of PNET with uncommon histological features.

Experimental petit mal-like seizure induced by microinjection of kainic acid into the unilateral mediodorsal nucleus of the thalamus.

The mediodorsal nucleus (MD) of the thalamus has reciprocal projections with the frontal cortex and limbic system, and may be involved in absence seizures. Kainic acid was injected into the left MD of Wistar rats, and behavior and electroencephalography were monitored for 24 hours, then continued intermittently for 8 weeks. The rat brains were then examined histologically. Brain metabolic changes were also investigated by intravenous injection of 100 microCi/kg of [(14)C]2-deoxyglucose to measure local cerebral glucose metabolism. Bilateral synchronous spike and wave complexes appeared almost 2 hours after kainic acid injection, and the waveforms continued for about 5-7 hours in the bilateral MDs, ipsilateral sensorimotor cortex, and basolateral nucleus of the amygdala. The associated behavioral changes were mainly those of behavioral arrest and staring, associated with occasional limbic seizures. Clear metabolic increases were found in the ipsilateral frontal cortex, hippocampus, and amygdala. The present results suggest that the MD was involved in both the mechanism of spike and wave complexes in the bilateral frontal cortices, and in seizure propagation to the limbic system. Consequently, kainic acid-induced MD seizure is associated with significant cognitive impairment and may explain the mechanism of petit mal seizure.

Focal cortical dysplasia: pathophysiological approach.

OVERVIEW: Clinical and experimental studies on focal cortical dysplasia (FCD) were carried out. MATERIALS AND METHODS: For the experimental study, an experimental FCD model of rats was developed. Twenty Wistar rats at 0-2 days after birth were used for the study. Kainic acid (KA) solution was injected stereotaxically into medial and lateral sites of the sensori-motor cortex. Bipolar electrodes were inserted in five rats. Their behavior and electroencephalogram (EEG) were recorded using a digital-video-EEG monitoring system. After observation periods of 1, 2, and 6 months, rats were perfused for pathological study. FCD was observed adjacent to the site of KA injection in all rats more than 1 month after the injection. RESULTS AND DISCUSSIONS: EEG recording demonstrated focal spike discharges in and around the site of injection. However, clinical seizure was not observed. Pathological studies showed decrease in GABA-A receptors and increase in GABA-B receptors not only in the lesion but also in perilesional areas. Fifteen surgical cases of FCD with intractable epilepsy were subjected to the clinical study. Neuro-imaging studies including high-resolution magnetic resonance imaging and single-photon emission computed tomography were performed. Conventional EEG studies demonstrated focal EEG abnormalities with epileptic phenomena. At surgery, intraoperative electrocorticography (ECoG) was performed to localize epileptic foci under neuroleptoanalgesia. Thirteen patients showed epileptiform discharges on preresection ECoG. All foci in non-eloquent areas were resected. Pathological studies including immunohistochemical staining were performed, and the characteristics of the FCD in relation to EEG findings were analyzed. Patients in whom total lesionectomy with complete focus resection was performed had favorable postoperative courses. Nine patients (64.3%) have been seizure-free with reduced medication, and significant improvement was achieved in two patients (14.3%). Electrophysiological examination revealed epileptogenecity not only in the lesions but also in perilesional areas. The immunohistochemical studies showed a decrease in GABA-A receptors and an increase in GABA-B receptors in both the lesions and perilesional areas, but N-methyl-D: -aspartate receptors were almost negative in both areas. Glutamate R1 was decreased in both areas, but glutamate R2 was increased in both areas. These findings support the results of a electrophysiological study. CONCLUSIONS: In conclusion, not only the epileptic property of experimental focal cortical dysplasia but also perilesional epileptogenesis was demonstrated. These findings supported the results of surgery for patients with focal cortical dysplasia. In cases of FCD, total removal of the lesion and resection of the perilesional epileptic focus are needed for a good outcome.

Clinical application of experimental cortical dysplasia in rats.

This report details clinical and experimental studies of focal cortical dysplasia. The first part deals with 14 surgical cases of children with intractable epilepsy. At surgery, intraoperative electrocorticography was performed to localize the epileptic foci under neuroleptanalgesia. Thirteen patients showed epileptiform discharges on this preresection electrocorticography. All foci in noneloquent areas were resected. Patients who had undergone total lesionectomy with complete focus resection showed the most favorable postoperative results. However, the positive correlation between the intraoperative electrocorticographic findings and the pathologic classification of cortical dysplasia was not found in the present study. Nine patients have been seizure free with reduced medication and two patients have achieved worthwhile improvement. We conclude that intraoperative electrocorticography can improve the surgical outcome for intractable epilepsy by localizing epileptic foci for resection. The second part describes a kainic acid-induced experimental model of focal cortical dysplasia, which demonstrated not only the epileptic properties of the dysplasia but also the perilesional epileptogenicity. The findings supported the surgical results for the patients with focal cortical dysplasia.

Clinical and experimental studies of epilepsy associated with focal cortical dysplasia.

The results of clinical and experimental studies on epilepsy associated with focal cortical dysplasia (FCD) are presented. We have been interested in the findings of abnormal increases in the numbers of small vessels in specimens of FCD resected from epilepsy patients. In the clinical study of 13 patients with epilepsy, specimens of FCD or dysembryoplastic neuroepithelial tumor (DNT) were examined using immunohistochemistry. The number of vessels in both lesions were greater than those in cortical specimens of autopsy cases without epilepsy. Because the vessels showed negative staining of VEGF, it was thought that the phenomenon of increase in the number of vessels was simply a hypervascularity, not a neovascularity. The local hypervascularity was expected to show local hyperperfusion in CBF-SPECT study, but interictal SPECT demonstrated local hypoperfusion and ictal SPECT showed hyperperfusion. This may have been caused by a functional change in those vessels. In the experimental study, we tried to make a new animal model of FCD to study epileptogenicity of FCD. When kainic acid had been infused into the neocortex in the neonatal rats, FCD was induced in adult Wistar rats. Histopathological examination revealed cortical dyslamination and abnormal neurons. On EEG, local spike bursts were elicited from the lesions, however, clinical seizures were not detected. Although the data are preliminary and observation over a longer period is required to determine whether spontaneous seizures will occur in this model, it is expected that this new model will be useful for studying epilepsy associated with FCD.