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Atypical teratoid/rhabdoid tumors (AT/RT) are rare, highly malignant neoplasms of the central nervous system that predominantly occur in infants, and are characterized by the presence of rhabdoid cells and inactivation of INI1 or (extremely rarely) BRG1. The vast majority of AT/RT are recognized as primary tumors; however, rare AT/RT or INI1-deficient RT arising from other primary tumors have been reported. To better characterize secondary RT, we performed a histological and molecular analysis of four RT arising from pleomorphic xanthoastrocytoma (PXA), anaplastic PXA, low-grade astrocytoma, or ependymoma. Histologically, although conventional AT/RT are usually not largely composed of rhabdoid cells, three secondary RT were composed mainly of rhabdoid cells, two of which arising from (anaplastic) PXA exhibited marked nuclear pleomorphism reminiscent of that in the precursor lesions. Regarding INI1 alterations, although mutations including small indels are frequent in conventional AT/RT, only in one secondary RT had a mutation. Moreover, together with previously reported cases, biallelic INI1 inactivation in secondary RT was mostly due to biallelic focal and/or broad deletions. Although conventional AT/RT have stable chromosomal profiles, i.e., the frequency of copy number changes involving chromosomes other than chromosome 22 is remarkably low, our array comparative genomic hybridization analysis revealed numerous copy number changes in the secondary RT. In conclusion, secondary RT of the central nervous system are clinicopathologically and molecularly different from conventional pediatric AT/RT, and a nosological issue is whether these secondary RT should be called secondary "AT/RT" as most of the reported cases were.

We describe a case of acute middle cerebral artery occlusion in a patient with ipsilateral internal carotid artery dysgenesis successfully treated with mechanical thrombectomy utilising a collateral pathway. During the procedure, a triaxial system using a balloon guiding catheter, flexible large lumen aspiration catheter and stent retriever was advanced from the left vertebral artery to the occluded left middle cerebral artery through the left posterior communicating artery. Because proximal aspiration from the balloon guiding catheter alone might have insufficient suction force due to the retrograde blood flow from large vascular communications (e.g. vertebral artery union), the tip of the flexible large lumen aspiration catheter was set at the proximal left middle cerebral artery, and distal aspiration was added during stent retrieval. A thrombolysis in cerebral infarction 2b result was achieved after the first pass. In this case, identification of carotid canal hypoplasia on computed tomography allowed for an immediate attempt of this alternative approach, avoiding a delay in the time to reperfusion.

The purpose of this study was to assess the complication risk rate and diagnostic yield in a series of 211 procedures performed by a consistent method at one institute.Two hundred and one patients underwent 211 stereotactic biopsy procedures for diagnosis of malignant brain tumor at Niigata University between 1987-2001. Indication for stereotactic biopsy is decided on the following factors: 1) the patient is elderly or unsuitable for craniotomy; 2) the tumor location is in a deep, diffusing, multiple, eloquent site; 3) cytoreductive surgery is not needed to treat the suspected pathology. The specimen was obtained from the target point of CT scan by the aspiration method under local anesthesia except for in six patients who were children or needed operation for a VP shunt under general anesthesia. The lesion was located in 114 cases of cerebral hemisphere, in 44 cases of basal ganglia, in 11 cases of cerebellum and in 11 cases of spreading site.Histological diagnosis was obtained in 188 of 211 procedures and the diagnostic yield was 93.5%. There were 104 high grade gliomas, 16 low grade gliomas, 5 germ cell tumors, 37 malignant lymphomas, 19 metastatic tumors and 13 negative/inconclusive biopsies. Sixteen patients incurred complications (7.6%). Four patients (1.6%) suffered intratumoral hemorrhage. Emergency craniotomy was performed in three patients and stereotactic aspiration of hematoma was carried out in one patient. Furthermore, of 12 complications, 9 occurred with the patient showing symptoms of worsening neurological deficit, 2 occurred with general convulsion and 1 occurred with severe facial pain.This study provided evidence that stereotactic biopsy was a safe and reliable tool for patients with unresectable malignant brain tumors.