Pediatric meningioma with rhabdoid features developed at the site of skull fracture: illustrative case.

BACKGROUND: Pediatric meningiomas are rare, and only a few cases attributed to trauma and characterized by development at the site of bone fracture have been reported. Both pediatric and traumatic meningiomas have aggressive characteristics. OBSERVATIONS: An 11-year-old boy who sustained a head injury resulting from a left frontal skull fracture 8 years previously experienced a convulsive attack. Imaging revealed a meningioma in the left frontal convexity. Total removal of the tumor with a hyperostotic section was successfully achieved. Intraoperative investigation showed tumor invasion into the adjacent frontal cortex. Histologically, the surgical specimen revealed a transitional meningioma with brain invasion and a small cluster of rhabdoid cells. This led to a final pathological diagnosis of an atypical meningioma with rhabdoid features. The postoperative course was uneventful, and no recurrence of the tumor was found after 2 years without adjuvant therapy. LESSONS: This is the first report of a pediatric meningioma with rhabdoid features occurring at the site of a skull fracture. Meningiomas that contain rhabdoid cells without malignant features are not considered to be as aggressive as rhabdoid meningiomas. However, the clinical course must be carefully observed for possible long-term tumor recurrence.

A Case of Suprasellar Papillary Glioneuronal Tumor Mimicking Craniopharyngioma.

Papillary glioneuronal tumor (PGNT) is a low-grade biphasic neoplasm with astrocytic and neuronal differentiation. This tumor occurs most commonly in the frontal and temporal lobes, close to the ventricles, and rarely in the cerebellum, brainstem, and pineal gland. However, there has been no report of this tumor in the suprasellar region to date. In this paper, we report a case of PGNT in the suprasellar region in a 16-year-old girl. Magnetic resonance imaging (MRI) revealed a cystic tumor with calcification that progressed from the anterior skull base to the suprasellar and temporal regions. Preoperatively distinguishing this tumor from craniopharyngioma was difficult because of the patient's age, localization of the tumor, and neuroimaging results. This case showed a backward shift of the chiasma, which is observed in only 4.7% of craniopharyngioma, as well as normal endocrine findings. Endocrinological examination and an MRI evaluation of the chiasmal shift may be useful for discrimination.

Superficial Temporal Artery-Middle Cerebral Artery Bypass Using a Thick STA after Endarterectomy: A Rescue Technique.

Background and Objective Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is a procedure to reconstruct cerebral blood flow in the MCA territory. In some cases, the STA wall is thickened and the size discrepancy between STA and MCA is apparent. In such a situation, STA-MCA bypass is challenging. We present two patients who underwent STA-MCA bypass using STA in which a thickened intima was removed. We discuss the usefulness of this rescue technique. Patients and Results A patient with an atherosclerotic MCA occlusion and another with an occluded internal carotid artery are included. Endarterectomy of STA was performed before or during anastomosis, and the intima-resected STA was anastomosed to MCA. In both cases, the STA was thick and hard, and it was difficult to anastomose the STA as it was to the MCA. Patency of the bypass was confirmed by postoperative angiography. Conclusion Endarterectomy of a thickened STA might be an effective rescue technique in cases with severely atherosclerotic STA in STA-MCA bypass.

Intraparenchymal hemorrhage from dural metastasis of breast cancer mimicking meningioma.

Intraparenchymal hemorrhage from dural metastasis of breast cancer is rare. A 54-year-old woman without a significant medical history showed altered consciousness and left hemiparesis. Radiological examination revealed an extra-axial mass in the right middle fossa with intraparenchymal hemorrhage and another mass invading the skull in the right parietal region. The pre-operative diagnosis was a sphenoid ridge meningioma presenting with intraparenchymal hemorrhage and another meningioma in the convexity. The tumors and hematoma were removed. Pathological findings of the tumors were compatible with adenocarcinoma. Systemic examination revealed breast cancer with metastasis to the spine. Although the radiological findings were similar to those of meningioma, a differential diagnosis of metastatic brain tumor with intraparenchymal hemorrhage should be taken into consideration.

Subarachnoid and intracerebral hemorrhage from intracranial hemangiopericytoma: An uncommon cause of intracranial hemorrhage.

BACKGROUND: Hemorrhage from an intracranial tumor is well known but uncommon. In cases of subarachnoid hemorrhage, aneurysm rupture is a main cause. CASE DESCRIPTION: A 64-year-old woman presented with sudden-onset motor aphasia. Computed tomography revealed subarachnoid hemorrhage, and intracerebral hemorrhage in the left temporal lobe. From the findings of pre-enhancement computed tomography, hemorrhage from a left middle cerebral artery aneurysm was initially suspected. Further radiological examinations demonstrated an enhanced mass with dural attachment in the left temporal region, but no vascular abnormality. Emergency craniotomy was performed, and the tumor and intracerebral hematoma were removed. The hemorrhage from fragile tumor vessels may destroy the tumor tissue and spread into the temporal lobe and subarachnoid space. Pathological examination of the tumor yielded findings consistent with hemangiopericytoma. Post-operatively, the patient was treated to prevent vasospasm. CONCLUSION: Although an intracranial tumor including hemangiopericytoma uncommonly causes subarachnoid hemorrhage, it should be taken into consideration as a source of intracranial hemorrhage.

Pseudoaneurysm Formation in Intracerebral Hematoma due to Ruptured Middle Cerebral Artery Aneurysm.

We report the case of a ruptured middle cerebral artery aneurysm that showed pseudoaneurysm formation in an intracerebral hematoma. A 61-year-old man who was taking warfarin complained of dysarthria. Three days later, he was found unconscious, and computed tomography on admission showed subarachnoid hemorrhage and an intracerebral hematoma in the left temporal lobe. Three-dimensional computed tomographic angiography showed an irregular-shaped aneurysm-like cavity extending from the left middle cerebral artery into the hematoma. Intraoperative observation revealed that the aneurysm itself was small and the lesion observed on computed tomography was a pseudoaneurysm that had formed in the hematoma. Pathologic examination of the aneurysm demonstrated that there was a thrombus at its tip. In this report, radiologic characteristics of three-dimensional computed tomographic angiography and etiology of a pseudoaneurysm in an intracerebral hematoma due to aneurysm rupture are discussed.

A chronic intracerebral fluid hematoma.

Intracerebral hematoma usually resolves and a chronic fluid hematoma is rare. We describe a rare case of intracerebral fluid hematoma. This report describes a case of intracerebral fluid hematoma mimicking a brain tumor and discusses the characteristics of this condition. A 70-year-old woman had a six-month history of memory disturbance. Computed tomography scan showed a low-density lesion with a partial high-density area in the right frontal lobe. MRI revealed a lesion of the main cystic portion showing high intensity on both T1 and T2 weighted images with a low-intensity solid portion in the anteromedial side. The lesion was adjacent to the lateral ventricle. Craniotomy was carried out and the lesion was removed. Pathological examination of the solid portion revealed that the diagnosis was reactive changes due to intracerebral hemorrhage. In our case, there was a possibility that the hematoma was diluted with cerebrospinal fluid, and coagulation might have been prevented.

Nucleostemin in injury-induced liver regeneration.

The high regenerative capacity of liver contributes to the maintenance of its size and function when injury occurs. Partial hepatectomy induces division of mature hepatocytes to maintain liver function, whereas severe injury stimulates expansion of undifferentiated hepatic precursor cells, which supply mature cells. Although several factors reportedly function in liver regeneration, the precise mechanisms underlying regeneration remain unclear. In this study, we analyzed expression of nucleostemin (NS) during development and in injured liver by using transgenic green fluorescent protein reporter (NS-GFP Tg) mice. In neonatal liver, the hepatic precursor cells that give rise to mature hepatocytes were enriched in a cell population expressing high levels of NS. In adult liver, NS was abundantly expressed in mature hepatocytes and rapidly upregulated by partial hepatectomy. Severe liver injury promoted by a diet containing 3,5-diethoxycarbonyl-1,4-dihydrocollidine induced the emergence of NS-expressing ductal epithelial cells as hepatic precursor cells. NS knockdown inhibited both hepatic colony formation in vitro and proliferation of hepatocytes in vivo. These data strongly suggest that NS plays a critical role in regeneration of both hepatic precursor cells and hepatocytes in response to liver injury.

Anaplastic meningioma with extremely rapid recurrence.

A 62-year-old woman presented with an uncommon case of anaplastic meningioma manifesting as recent memory disturbance. Magnetic resonance imaging revealed a mass located in the right temporal lobe. She became unconscious because of uncal herniation and underwent urgent surgery. The tumor was completely resected, except for a lesion tightly attached to arteries. Histological examination indicated the presence of anaplastic meningioma with an extremely high MIB-1 labeling index (70%). After 43 days, the patient developed local recurrence and dissemination in the left temporal lobe. The exceptionally high MIB-1 labeling index corresponded with a short tumor doubling time (8.2 days). Whole-brain irradiation and linear accelerator surgery for disseminated lesions were performed, and the tumor growth halted. Although meningiomas rarely show malignant behavior, corresponding to World Health Organization grade III, it is necessary to consider malignant behavior when treating meningiomas.

NKX2.2 suppresses self-renewal of glioma-initiating cells.

Glioblastoma (GBM) is the most aggressive and destructive form of brain cancer. Animal models that can unravel the mechanisms underlying its progression are needed to develop rational and effective molecular therapeutic approaches. In this study, we report the development of mouse models for spontaneous gliomas representing distinct progressive stages of disease that are governed by defined genetic alterations. Neural stem/progenitor cell (NPC)-specific constitutive Ras activation in vivo plus p53 deficiency led to development of primarily anaplastic astrocytoma (grade III), whereas combined loss of p53 plus p16(Ink4a)/p19(Arf) led to development of GBM (grade IV) at 100% penetrance within 6 weeks. These glioma models showed enhanced stem cell properties (stemness) accompanied by malignant progression. Notably, we determined that, in our models and in human specimens, downregulation of the homeodomain transcription factor NKX2.2, which is essential for oligodendroglial differentiation, was correlated with increased tumor malignancy. NKX2.2 overexpression by GBM-derived glioma-initiating cells (GIC) induced oligodendroglial differentiation and suppressed self-renewal capacity. By contrast, Nkx2.2 downregulation in mouse NPCs accelerated GBM formation. Importantly, the inhibitory effects of NXK2.2 on GIC self-renewal were conserved in human cells. Thus, our mouse models offer pathobiologically significant advantages to investigate the nature of brain tumors, with improved opportunities to develop novel mechanism-based therapeutic approaches.

Giant subependymoma developed in a patient with aniridia: analyses of PAX6 and tumor-relevant genes.

We observed an unusually large subependymoma in a female patient with congenital aniridia. To analyze the genetic mechanisms of tumorigenesis, we first examined the paired box 6 (PAX6) gene using both tumor tissue and peripheral lymphocytes. Tumor suppressor activity has been proposed for PAX6 in gliomas, in addition to its well-known role in the eye development. Using genomic quantitative PCR and loss of heterozygosity analysis, we identified hemizygous deletions in the 5'-region of PAX6. In lymphocytes, the deletion within PAX6 spanned from between exons 6 and 7 to the 5'-upstream region of the gene, but did not reach the upstream gene, RNC1, which is reported to be associated with tumors. The subependymoma had an additional de novo deletion spanning from the intron 4 to intron 6 of PAX6, although we could not completely determine whether these two deletions are on the same chromosome or not. We also examined other potentially relevant tumor suppressor genes: PTEN, TP53 and SOX2. However, we detected no exonic mutations or deletions in these genes. Collectively, we speculate that the defect in PAX6 may have contributed to the extremely large size of the subependymoma, due to a loss of tumor suppressor activity in glial cell lineage.

Identification of tumor-initiating cells in a highly aggressive brain tumor using promoter activity of nucleostemin.

Controversy remains over whether the cancer stem cell (CSC) theory applies to all tumors. To determine whether cells within a highly aggressive solid tumor are stochastically or hierarchically organized, we combined a reporter system where the nucleostemin (NS) promoter drives GFP expression (termed NS-GFP) with a mouse brain tumor model induced by retroviral Ras expression on a p16(Ink4a)/p19(Arf)-deficient background. The NS-GFP system allowed us to monitor the differentiation process of normal neural stem/precursor cells by analyzing GFP fluorescence intensity. In tumor-bearing mice, despite the very high frequency of tumorigenic cells, we successfully identified the NS-GFP(+) cells as tumor-initiating cells (T-ICs). The clonal studies conclusively established that phenotypical heterogeneity can exist among the cells comprising a genetically homogeneous tumor, suggesting that this aggressive brain tumor follows the CSC model. Detailed analyses of the NS-GFP(+) brain tumor cells revealed that T-ICs showed activation of the receptor tyrosine kinase c-Met, which functions in tumor invasiveness. Thus, the NS-GFP system provides a powerful tool to elucidate stem cell biology in normal and malignant tissues.

Identification of stem cells during prepubertal spermatogenesis via monitoring of nucleostemin promoter activity.

The nucleostemin (NS) gene encodes a nucleolar protein found at high levels in several types of stem cells and tumor cell lines. The function of NS is unclear but it may play a critical role in S-phase entry by stem/progenitor cells. Here we characterize NS expression in murine male germ cells. Although NS protein was highly expressed in the nucleoli of all primordial germ cells, only a limited number of gonocytes showed NS expression in neonatal testes. In adult testes, NS protein was expressed at high levels in the nucleoli of spermatogonia and primary spermatocytes but at only low levels in round spermatids. To evaluate the properties of cells expressing high levels of NS, we generated transgenic reporter mice expressing green fluorescent protein (GFP) under the control of the NS promoter (NS-GFP Tg mice). In adult NS-GFP Tg testes, GFP and endogenous NS protein expression were correlated in spermatogonia and spermatocytes but GFP was also ectopically expressed in elongated spermatids and sperm. In testes of NS-GFP Tg embryos, neonates, and 10-day-old pups, however, GFP expression closely coincided with endogenous NS expression in developing germ cells. In contrast to a previous report, our results support the existence in neonatal testes of spermatogonial stem cells with long-term repopulating capacity. Furthermore, our data show that NS expression does not correlate with cell-cycle status during prepuberty, and that strong NS expression is essential for the maintenance of germline stem cell proliferation capacity. We conclude that NS is a marker of undifferentiated status in the germ cell lineage during prepubertal spermatogenesis.