A rare case of extraventricular neurocytoma.

We report an unusual case of extraventricular (cerebral) neurocytoma with a long, 25-year history, and which appeared to transform to neuroblastoma. In 1978, an 18-year-old woman was treated for right frontal oligodendroglioma. Eighteen years later (in 1996), recurrence of tumor in the fourth ventricle was noted and was treated with gamma-knife radiotherapy. The tumor shrunk transiently, but 7 years later (in 2004), MRI study demonstrated a second recurrence and ventricular dissemination. Partial removal was performed, and histological examination revealed that tumor cells had round or oval nuclei with halos. Frequent mitoses and vascular proliferation were observed. The MIB-1 LI was 80%. Despite postoperative whole-brain radiotherapy to a total dose of 30 Gy, the tumor progressed, and she died at 4 months after the second surgery.

[Operative case of isomorphic astrocytoma].

Diffuse astrocytomas are classified as WHO Grade II tumors. Recently, a subtype presenting with better prognosis has been proposed, and it is known as "isomorphic astrocytoma." A clinical case that we encountered was believed to be categorized as this subtype; it has been presented in this report. The patient was a 20-year-old male with a chief complaint of intractable epileptic seizures. He experienced his first attack at 16 years of age in July 2001, and it was a generalized seizure. Anticonvulsants prescribed by a previous doctor had no effect on controlling the seizures. MRI performed in March 2004 showed a lesion approximately 2.0 cm in diameter in the left temporal lobe. The patient was referred to our institution for further investigation of the lesion and therapy. Electroencephalography and magnetoencephalography were used to assess the lesion at seizure focus. The tumor was resected under awake surgery. The pathological diagnosis was diffuse astrocytoma, but this tumor was considered to be the isomorphic subtype. Some parts of the tumor showed a relatively high MIB-1 labeling index (LI) of 9.2%, and additional 50-Gy radiotherapy was performed. The postoperative course was uneventful and despite decreasing the anticonvulsant dosage, he has remained seizure free. Isomorphic astrocytoma is characterized by prolonged epileptic seizures, a low MIB-1 LI, and better prognosis. In our case, since the MIB-1 LI was higher in some parts of the tumor, the appropriate therapy for WHO Grade II tumors was performed. However, this case was considered representative of isomorphic astrocytoma. No reports of this tumor subtype have been previously described in Japan. Therefore, this report is the first case of isomorphic astrocytoma reported to Japanese literature.

Inhibition of angiogenesis in human glioma cell lines by antisense RNA from the soluble guanylate cyclase genes, GUCY1A3 and GUCY1B3.

Malignant gliomas, most of which show an elevated level of vascular endothelial cell growth factor (VEGF) expression, are well known for their hyper-vascularity. One of the possible inducers of VEGF in tumor cells is nitric oxide (NO), which is synthesized by NO synthase and stimulates soluble guanylate cyclase (GC) in tumor cells. Here, we report that 2 of 9 human glioma cell lines, CCF-STTG1 and U-87MG, overproduced cyclic GMP (cGMP) and showed increased expression of both or either subunits of soluble GC1, GUCY1A3 and GUCY1B3. Transfection of antisense GUCY1A3 or GUCY1B3 into these two glioma cell lines markedly reduced the content of cGMP and expression of VEGF. The angiogenic activity in vitro was subsequently inhibited, which was determined by induction of HUVEC cell growth. Furthermore, subcutaneous tumor formation by U-87MG cells in nude mice was dramatically suppressed to less than 0.05% in volume by transfection of either antisense GUCY1A3 or antisense GUCY1B3, which was accompanied by the significant decrease in vascular index to about 10%. These findings demonstrate that cGMP is an upstream mediator of VEGF expression in glioma cells and that soluble guanylate cyclases could be the target molecules for controlling neo-vascularization in a subset of human malignant gliomas.

[A case of bilateral extracranial carotid artery aneurysms caused by Takayasu's arteritis].

We describe here successful surgical treatment of a rare case of a rapidly enlarged aneurysm due to Takayasu's arteritis. A 22-year-old woman presented with a 1-month history of hoarseness and left neck pain. Contrast-enhanced computerized tomography showed an unruptured partially thrombosed aneurysm, and angiography revealed a large aneurysm of the common carotid artery. After hospitalization, the symptoms, interestingly, resolved spontaneously. While angiography at 2 weeks after admission showed the aneurysm to have reduced in size, 2 months later it showed the left common carotid artery aneurysm to be substantially enlarged in size and aneurysmal formation of the right external carotid artery. Surgical intervention was performed for the left common carotid artery aneurysm because rapid enlargement indicated the risk of aneurysmal rupture, and the thrombosis might cause embolic occlusion of the cerebral arteries. The left common carotid artery including enlarged aneurysm was trapped and anastomosed with a Gore-Tex graft (6-mm inner diameter) to left internal carotid artery. Histological examination of the arterial wall showed inflammatory change, destruction of the medial elastic fibers, and granulation with multinucleated giant cells. The postoperative course was uneventful, and no new vascular lesion was observed 3 years after operation. We demonstrated the bilateral extracranial carotid artery aneurysms caused by Takayasu's arteritis, which was the first case to be reported in the literature.

Two cases of atypical central neurocytomas.

Central neurocytomas (CNs) are usually considered benign; however, some subsets of these tumors with histologic atypia and elevated proliferation potential have been reported to have a poor outcome. It has been proposed that those CNs exhibiting a MIB-1 labeling index (LI) greater than 2% and/or vascular proliferation be defined as atypical central neurocytoma (ACN). Two cases of ACN are reported here. Case 1 was a 13-year-old male who complained of headache. An MRI showed an enhancement of the tumor in the third ventricle and left lateral ventricle. The tumor was completely removed transcortically by a left frontotemporal craniotomy. The tumor showed anaplastic features, including microvascular proliferation, mitosis, and necrosis. The MIB-1 LI was 7.8%. The patient received 50Gy of focal irradiation. After 16 months of follow-up, no recurrence was observed. Case 2 was a 17-year-old female who presented with headache. An MRI showed an enhancement of the tumor in the right lateral ventricle. To preserve the internal cerebral vein, the tumor was partially removed by the transcingulate approach after a bifrontal craniotomy. Histologically, the tumor displayed the typical features of a CN. The MIB-1 LI was 7.0%. Complete remission was achieved through 50Gy of focal irradiation. After 15 months of follow-up, there was no recurrence. The differences in the histopathological findings in these two cases indicate the presence of a variety of histopathological features among ACNs.