P10.19.B An immunotoxin targeting CD317 for the treatment of glioblastoma

Background

CD317 is an interferon-inducible cell surface receptor expressed in several solid cancer types. HM1.24-ETA’ is a small immunotoxin with a CD317 single-chain variable fragment (svFv) antibody fused to a truncated version of Pseudomonas aeruginosa exotoxin A (ETA’) that is explored as a novel therapeutic approach in CD317-expressing tumors.

Material and Methods

CD317 mRNA expression in human gliomas and its association with survival was analyzed using the database of the Cancer Genome Atlas (TCGA). CD317 protein levels in human gliomas were assessed by immunohistochemistry. CD317 mRNA expression was assessed by RT-PCR and CD317 protein levels by flow cytometry in 13 human glioma cell lines in vitro. Efficacy of HM1.24-ETA’ was analyzed in acute cytotoxicity assays in vitro. Finally, HM1.24-ETA’ was evaluated in the intracranial human LN-229 glioma xenograft nude mouse model after intravenous injection.

Results

Interrogation of the TCGA database showed that increased CD317 mRNA expression correlated with grade of malignancy among isocitrate dehydrogenase (IDH) wildtype and IDH-mutant gliomas. Enhanced CD317 mRNA expression was associated with inferior survival in glioblastoma and astrocytoma, IDH-mutant, WHO grade 4. Immunohistochemistry confirmed CD317 overexpression in human glioblastoma compared to lower grade astrocytomas. CD317 was expressed heterogeneously on mRNA and protein levels in glioma cell lines in vitro. HM1.24-ETA’ induced acute cytotoxicity in CD317-positive glioma cells in vitro. CD317 expression and susceptibility to HM1.24-ETA’-induced cell death were enhanced by interferon-β. HM1.24-ETA’ prolonged survival in the LN-229 xenograft nude mouse model.

Conclusion

These data define CD317 as a novel target for treatment of human gliomas with immunoconjugates.

Bevacizumab plus hypofractionated radiotherapy versus radiotherapy alone in elderly patients with glioblastoma: the randomized, open-label, phase II ARTE trial

Background

The addition of bevacizumab to temozolomide-based chemoradiotherapy (TMZ/RT → TMZ) did not prolong overall survival (OS) in patients with newly diagnosed glioblastoma in phase III trials. Elderly and frail patients are underrepresented in clinical trials, but early reports suggested preferential benefit in this population.

Patients and methods

ARTE was a 2 : 1 randomized, multi-center, open-label, non-comparative phase II trial of hypofractionated RT (40 Gy in 15 fractions) with bevacizumab (10 mg/kg×14 days) (arm A, N = 50) or without bevacizumab (arm B, N = 25) in patients with newly diagnosed glioblastoma aged ≥65 years. The primary objective was to obtain evidence for prolongation of median OS by the addition of bevacizumab to RT. Response was assessed by RANO criteria. Quality of life (QoL) was monitored by the EORTC QLQ-C30/BN20 modules. Exploratory studies included molecular subtyping by 450k whole methylome and gene expression analyses.

Results

Median PFS was longer in arm A than in arm B (7.6 and 4.8 months, P = 0.003), but OS was similar (12.1 and 12.2 months, P = 0.77). Clinical deterioration was delayed and more patients came off steroids in arm A. Prolonged PFS in arm A was confined to tumors with the receptor tyrosine kinase (RTK) I methylation subtype (HR 0.25, P = 0.014) and proneural gene expression (HR 0.29, P = 0.025). In a Cox model of OS controlling for established prognostic factors, associations with more favorable outcome were identified for age <70 years (HR 0.52, P = 0.018) and Karnofsky performance score 90%-100% (HR 0.51, P = 0.026). Including molecular subtypes into that model identified an association of the RTK II gene methylation subtype with inferior OS (HR 1.73, P = 0.076).

Conclusion

Efficacy outcomes and exploratory analyses of ARTE do not support the hypothesis that the addition of bevacizumab to RT generally prolongs survival in elderly glioblastoma patients. Molecular biomarkers may identify patients with preferential benefit from bevacizumab.

Clinical trial registration number

NCT01443676.

Phase II study of hydroxyurea for unresectable meningioma (Southwest Oncology Group S9811)

2063

Background: Meningiomas account for 15%-18% of CNS tumors. Although benign, recurrence is seen in 16%-39% of cases, depending on the extent of resection possible. Tumor location may make further resection hazardous. Chronic hydroxyurea (HU) was reported to produce well documented objective responses in a small series of patients, with gradual regression occurring over 6–10 months. Induction of apoptosis was furthermore demonstrated with HU in primary benign meningioma explant cultures. The S9811 phase II trial was undertaken to estimate the objective response rate, if any, of unresectable benign meningioma to this HU regimen. Methods: Eligibility required unresectable, measurable, residual or recurrent, histologically-proven benign meningioma. Progressive tumor or progressive neurologic deficit was required. No prior cytotoxics, no radiation therapy for >1 year. Age > 18, adequate hematologic reserve, PS 0–2. HU 20 mg/kg/day po was given for up to 2 years if there was no progressive disease. Single-stage accrual of 38 pts would have allowed detection of 5% null hypothesis response probability vs. 20% with 90% power; the 28 pts actually accrued provide 81% power. Results: Between November 98 and June 2005, 29 pts were accrued, with study closure due to slow accrual. 1 ineligible. Response assessment showed CR+PR 0% (95% CI 0–12%); SD 71% (95% CI 51–87%); PD 21% (95% CI 8–41%); undetermined 7%. Median PFS was 27 months. (95% CI 12–29 months.); 3-year PFS 43% (95% CI 25–61%). Median OS has not been reached. Seven patients were removed from study for toxicity (5/7 hematological). Toxicity was mainly hematologic: 11/28 (39%) grade 3, 2/28 (11%) grade 4. Grade 3 non-hematologic toxicity was seen in 7/28 (25%). Conclusions: Chronic HU therapy for unresectable benign meningioma resulted in an estimated objective response rate of < 12%. Whether the stable disease rate seen differs in any way from what can be expected from the natural history of meningioma cannot be determined from this phase II study design.

No significant financial relationships to disclose.

Rare primary CNS anaplastic large cell lymphoma in an immunocompetent adult: a clinical-pathologic case report and review case of the literature

OBJECTIVE AND IMPORTANCE

Isolated anaplastic large cell lymphoma (ALCL) presenting in the primary central nervous system is distinctly uncommon. The authors describe a case that clinically and radiographically simulated a primary glial neoplasm.

CLINICAL PRESENTATION

A 39-year-old immunocompetent male presented with seizures and a rapidly enlarging right occipital/parietal lesion. Magnetic resonance images demonstrated a right occipitoparietal lesion, hypodense on T1WI, with patchy contrast enhancement with gadolinium and significant white matter edema pattern on T2WI along with mass effect and midline shift.

INTERVENTION

The patient underwent a frameless stereotactic assisted needle biopsy. There appeared to be a clear demarcation between white matter and tumor with no obvious necrosis. Biopsy showed a proliferation of single cells and poorly cohesive groups of cells with large, pleomorphic nuclei, many containing prominent nucleoli, and a moderate amount of cytoplasm. Immunohistochemical staining revealed CD-30 and ALK-positivity typical of ALCL, a rare form of T-cell lymphoma. An extensive workup revealed neither systemic disease nor evidence of immunocompromise.

CONCLUSION

Reported in less than 20 patients, primary ALCL in an immunocompetent patient is rarely found intracranially; however, its ability to mimic glial neoplasms as well as other pathologies underlines its importance.

MGMT methylation in newly-diagnosed glioblastoma multiforme (GBM): From the S0001 phase III study of radiation therapy (RT) and O6-benzylguanine, (O6BG) plus BCNU versus RT and BCNU alone for newly diagnosed GBM

1512

Background: Glioblastoma multiforme (GBM) is a high grade primary brain neoplasm associated with a median survival of less than a year. Historically, one-third of patients seem to benefit from treatment with alkylating chemotherapy. This minority may correspond to a population with decreased levels of active O6-methylguanine- methyltransferase enzyme (MGMT). MGMT repairs tumor DNA damaged by chemotherapy, allowing continued replication after exposure to treatment. Patients with low tumor MGMT activity may be more likely to respond to alkylating treatment. Hypermethylation of the MGMT promoter region leads to decreased transcription of the enzyme and is associated with improved outcome in GBM patients treated with radiation and alkylating chemotherapy. Methods: We studied a patient cohort with newly diagnosed GBM registered on Southwest Oncology Group protocol S0001, a phase III randomized, two arm clinical trial investigating an inhibitor of MGMT (O6-benzylguanine, O6BG). Both groups received standard radiation and BCNU (carmustine). The experimental group additionally received O6BG. We determined polymerase chain reaction (PCR) methylation status of the promoter region of MGMT in 88 patients with adequate tissue samples. In 41 cases, we were able to obtain successful PCR results. Results: 28 of 41 samples (68%) were found to be unmethylated and 13 of 41 (32%, 95% c. i. 18% to 50%) were methylated. Patients with methylated MGMT had a median survival of 12.6 months (95% c.i. of 7.8–15.8 months). Patients with unmethylated MGMT had a median survival of 10.6 months (95% c.i. of 8.7–12.0 months). Median progression-free survivals were 4.5 and 3.1 months respectively, for the methylated and unmethylated groups. Conclusions: This result is consistent with prior studies which showed that approximately two-thirds of patients express MGMT, and accordingly, are resistant to alkylating agents. The subgroup of patients without promoter methylation may be more likely to benefit from treatment with O6BG. Analysis of MGMT promoter methylation status per study treatment group, and correlation with median survival and progression-free survival will be presented.

No significant financial relationships to disclose.

Relationship between radiation injury and Alzheimer-related neurodegenerative changes

The relationship between radiation injury and other neurodegenerative changes such as the formation of neuritic or diffuse plaques and tangles have received little attention in the literature. In the current study, archival tissue was examined from 485 patients with the diagnosis of either a primary or metastatic brain tumor, who had received radiation therapy between the initial and subsequent pathological study (either surgical or autopsy). Of those cases, 20 were identified that also contained cerebral cortex in both specimens. Sections were stained with the modified Bielschowsky technique and immunohistochemical preparations for beta-amyloid. Contrary to previous reports, the present study did not identify neurodegenerative changes typical of Alzheimer's disease as a consequence of radiation therapy.

Chromogenic in situ hybridization accurately identifies EGFR amplification in small cell glioblastoma multiforme, a common subtype of primary GBM

Primary glioblastoma multiforme (GBM) commonly overexpresses the epidermal growth factor receptor (EGFR) gene and its ligand-independent mutant, EGFRvIII. Amplification of the EGFR gene has been implicated in the pathogenesis of primary GBM, in particular the small cell phenotype, and this finding may contribute to its aggressive clinical behavior. Anti-EGFR clinical trials for GBM are being conducted, and it would be useful to identify a rapid technique to determine whether EGFR expression and the small cell phenotype are associated with a response to therapy. In the present study we examined 56 cases of GBM using chromogenic in situ hybridization (CISH). CISH analysis and morphology identified 22 small cell (SCGBM) and 22 non-small cell glioblastoma (NSCGBM), and 12 cases of a mixed phenotype. Fourteen cases of SCGBM (14/22) showed EGFR amplification, while only 5 NSCGBM (5/22) cases showed amplification. We have therefore used CISH as an efficient, economic and reliable means for routinely assessing EGFR amplification in GBM, including the small cell variant.

Neuropathology of the brain and spinal cord in human West Nile virus infection

OBJECTIVE

To describe the histopathology of the brain and spinal cord in human West Nile virus (WNV) infection.

MATERIALS AND METHODS

Single case report, including premortem clinical and laboratory findings, and autopsy.

RESULTS

An 83-year-old female presented with acute confusion, high fevers, dysarthria and generalized subjective weakness, with decreased deep tendon reflexes and weakness on physical examination. Electromyography showed evidence of a sensorimotor axonal polyneuropathy of the right-sided extremities. She became ventilator-dependent and died after a 2-week ICU stay, following withdrawal of life support. WNV infection was confirmed premortem by detection of IgM antibodies from serum and CSF and postmortem by RT-PCR from brain tissue. Examination of the brain parenchyma showed scattered microglial aggregates accompanied by perivascular chronic inflammation. The leptomeninges showed focal lymphocytic infiltrates. Examination of the spinal cord showed lymphocytic infiltrates in nerve roots and within the cord proper, with focal microglial nodules and neuronophagia in the ventral horns. Special stains were negative for a demyelinating process. General autopsy revealed only emphysema and atelectasis.

CONCLUSIONS

The findings in this case suggest direct viral infection of the spinal cord and nerve roots as the mechanism of the flaccid paralysis often observed in patients infected with WNV. Findings are reviewed in comparison with other reports of neuropathologic findings in human WNV infection.

Alpha-internexin expression in medulloblastomas and atypical teratoid-rhabdoid tumors

OBJECTIVE

To determine whether medulloblastomas and atypical teratoid/rhabdoid tumors express alpha-internexin, an intermediate filament protein that is expressed in normal neurons undergoing maturation and differentiation.

MATERIALS AND METHODS

28 medulloblastomas and 5 atypical teratoid/rhabdoid tumors were examined for the immunohistochemical expression of alpha-internexin, as well as the neuronal markers peripherin and synaptophysin, and glial fibrillary acidic protein.

RESULTS

Overall, 21 of 28 medulloblastomas (75%) expressed alpha-internexin. More specifically, alpha-internexin expression was observed in 6 of 10 (60%) classic medulloblastomas, 12 of 14 (86%) desmoplastic medulloblastomas, 2 of 3 (67%) nodular medulloblastomas, and in one medullomyoblastoma. Similarly, 4 of 5 (80%) atypical teratoid/rhabdoid tumors expressed alpha-internexin. The extent of staining for alpha-internexin tended to be less than that of synaptophysin for both medulloblastomas (75% vs 93%) and atypical teratoid/rhabdoid tumors (80% vs 100%). In contrast to alpha-internexin, peripherin was expressed in only 4 medulloblastomas and one atypical teratoid/rhabdoid tumor.

CONCLUSIONS

Alpha-internexin is expressed in the majority of medulloblastomas and atypical teratoid/rhabdoid tumors, indicating that these primitive tumors usually exhibit neuronal differentiation.

Characterization of initiated cells in N-methylnitrosourea-induced carcinogenesis of the CNS in the adult rat

Glial tumors may originate from the malignant transformation of multipotent glial progenitor cells, but tools to study malignant transformation leading to gliomas are limited by the lack of biological systems that represent early stages of this disease in adult animals. In order to characterize the initiated cells that give rise to gliomas, we have employed the N-methylnitrosourea (MNU) model for induction of brain tumors in adult rats (Rushing et al., 1998). Specifically, we have isolated and cultured transformed (premalignant) cells from normal-appearing brains of rats exposed to MNU for 10 weeks and from histologically abnormal brains of rats exposed to MNU for 15 weeks. We compared them with cells cultured from control animals under identical conditions. Cultured cells were classified according to their morphology, immunophenotype, karyotype, proliferation capacity, and tumorigenicity in athymic mice. Cultures from untreated normal rat brains grew as monolayers and had normal karyotypes (42 X,Y), epithelioid morphology, and slow proliferative capacity (doubling time > 120 h). In contrast, cultured cells from brains of MNU-exposed animals had karyotypes that ranged from normal to highly aneuploid. Aneuploid lines grew rapidly in multilayers (doubling time < 24 h), had differentiated astrocytic or oligodendroglial morphology and immunohistochemical staining profile, and yielded tumors in athymic mice. Initiated cells with minor chromosomal aberrations assumed mixed bipolar or tripolar morphologies in high density cultures, proliferated rapidly, but showed contact inhibition and failed to induce tumors when injected s.c. in athymic mice. In general, lines showing no evidence of chromosomal aberrations had the most epithelioid morphology, proliferated slowly (doubling time > 72 h), and retained strict contact growth inhibition. The presumed undifferentiated glial progenitor cells in culture from either control or MNU-treated rats variably expressed markers such as vimentin, nestin, and NG2 proteoglycan, and they weakly expressed the mature astrocytic or oligodendroglial markers glial fibrillary acidic protein or galactocerbroside, respectively. These cultures differentiated to bipolar-tripolar morphology with concomitant maturation to a GFAP+ or GalC+ phenotype upon exposure to secondary messengers such as dibutyryl-cyclic-AMP and/or growth factors such as basic fibrillary growth factor. Continuous stimulation with these messengers resulted in terminal differentiation and consequent death upon withdrawal of the stimulus. These results provide information that could lead to detailed characterization of initiated, premalignant cells in the adult brain and to a better understanding of glial carcinogenesis.

Ablation of NF1 function in neurons induces abnormal development of cerebral cortex and reactive gliosis in the brain

Neurofibromatosis type 1 (NF1) is a prevalent genetic disorder that affects growth properties of neural-crest-derived cell populations. In addition, approximately one-half of NF1 patients exhibit learning disabilities. To characterize NF1 function both in vitro and in vivo, we circumvent the embryonic lethality of NF1 null mouse embryos by generating a conditional mutation in the NF1 gene using Cre/loxP technology. Introduction of a Synapsin I promoter driven Cre transgenic mouse strain into the conditional NF1 background has ablated NF1 function in most differentiated neuronal populations. These mice have abnormal development of the cerebral cortex, which suggests that NF1 has an indispensable role in this aspect of CNS development. Furthermore, although they are tumor free, these mice display extensive astrogliosis in the absence of conspicuous neurodegeneration or microgliosis. These results indicate that NF1-deficient neurons are capable of inducing reactive astrogliosis via a non-cell autonomous mechanism.

Infections of the nervous system

This article surveys common causes and pathologic features of nervous system infections within the general population. Special consideration is given to infections in people with the HIV virus.

Recurrent (nonfamilial) hemangioblastomas involving spinal nerve roots: case report

OBJECTIVE AND IMPORTANCE

Spinal nerve root hemangioblastomas are rare and are reported mainly in patients with von Hippel-Lindau (VHL) syndrome. The pathogenesis of so-called nonfamilial lesions is virtually unknown. We discuss, mainly from a molecular perspective, a unique patient with sporadic, recurrent hemangioblastomas restricted to spinal nerve roots.

CLINICAL PRESENTATION

A 53-year-old man who had had a surgically corrected lumbosacral meningomyelocele presented on at least three occasions during a 17-year period with multifocal capillary hemangioblastomas involving spinal nerve roots. On each occasion, tumors appeared on a different nerve root, with the majority located in the midcervical segments. The patient had no clinical features or family history of VHL syndrome.

TECHNIQUE

To obtain a clearer understanding of the pathogenesis of this unusual case and its relationship to VHL syndrome, molecular analysis of the VHL gene was performed by use of complete sequence analysis and loss of heterozygosity studies on deoxyribonucleic acid derived from the patient's blood leukocytes and three separately resected hemangioblastomas.

CONCLUSION

Germ-line molecular analysis performed on all three exons in the VHL gene coding region did not indicate that any mutations were present. Loss of heterozygosity analysis of deoxyribonucleic acid from the three hemangioblastoma resections showed normal heterozygosity in the 3p25-26 region. Complete VHL gene sequence analysis did not demonstrate a somatic mutation in the coding region of the VHL gene in any of the three tumors, thereby supporting the loss of heterozygosity data that a molecular event directly involving the VHL gene may not be the causative factor in their tumorigenesis.

Proliferative activity in craniopharyngiomas: clinicopathological correlations in adults and children

BACKGROUND

Craniopharyngiomas are slow-growing, locally invasive intracranial tumors that can generate considerable morbidity, and recurrences are often difficult to manage. Because reliable morphologic criteria for accurately predicting the clinical outcome of these tumors are lacking, we evaluated the growth potential of craniopharyngiomas by measuring their proliferative activity based on MIB-1 immunostaining for the Ki-67 antigen, which is expressed during all phases of the cell cycle except G(0.)

METHODS

Paraffin sections from 37 cases of craniopharyngiomas were immunostained with the monoclonal antibody MIB-1, and a labeling index was derived in each case from an the with the highest labeling.

RESULTS

MIB-1 immunoreactivity was mainly confined to the peripheral palisaded epithelium of craniopharyngiomas. In adult craniopharyngiomas, MIB-1 labeling indices (MIB-LI) varied from 0.1% to 34.6% (mean 8.9%; SD 9. 8), and in pediatric tumors the indices ranged from 1.8% to 15.0% (mean 6.3%; SD 3.7). MIB-LI was not found to be an independent predictor of recurrence, although in all the pediatric cases that recurred, MIB-LI in the second specimen was greater.

CONCLUSIONS

The actively proliferating compartment in craniopharyngiomas seems to be the peripheral palisaded epithelium. Low MIB-LI observed in the majority of tumors is in concordance with the slow growth and low-grade invasiveness associated with craniopharyngiomas. However, unlike other intracranial neoplasms, where Ki-67 labeling indices have been useful in predicting tumor behavior, a clear relationship could not be demonstrated between MIB-1 immunoreactivity, morphological features and clinical outcomes in adults or children with craniopharyngiomas.

Prognostic value of proliferation index and expression of the RNA component of human telomerase (hTR) in papillary meningiomas

Papillary meningioma is a rare subtype of meningioma that often behaves aggressively. In order to characterize factors that may influence this behavior, we chose to compare MIB-1 labeling index (LI) and telomerase RNA localization (hTR) in papillary meningiomas, meningiomas, and atypical meningiomas. LI is now often used to supplement histologic grade in the evaluation of these lesions. More recent studies indicate that increased expression of hTR is detected in many neoplastic cells, and may play an essential role in cell immortalization. The study group consisted of five papillary meningiomas (and a recurrence in one case), 11 conventional meningiomas, and eight atypical meningiomas. Conventional meningiomas showed either negative or 1 + hTR. Atypical meningiomas showed 1 + hTR. Papillary meningiomas showed the highest hTR (five of six, including recurrence, 2-3+ and one 1+). Generally, the LI was very low for conventional meningiomas (< 2%). The LI of atypical meningiomas ranged from 3-19%, mean 12%, and from 5.5-17.5%, mean 11.75% for papillary meningiomas. LI differentiated between meningiomas, and papillary or atypical meningiomas. hTR further delineated papillary (moderate to high) from atypical meningiomas (low). The combined variable of LI and hTR expression could be a useful independent prognostic indicator in patients with papillary meningioma.

Alpha-synuclein expression in central nervous system tumors showing neuronal or mixed neuronal/glial differentiation

Alpha-synuclein (alpha-synuclein) is a member of a family of cytoplasmic proteins found predominantly and abundantly in the brain, and concentrated in pre-synaptic nerve terminals, near vesicles. We hypothesized that an antibody to alpha-synuclein could be a useful marker of neuronal differentiation in central nervous system (CNS) tumors. Twenty tumors known to have neuronal or mixed neuronal/glial differentiation ( 11 gangliogliomas, 2 anaplastic gangliogliomas, 5 gangliocytomas, and 2 ganglioneuroblastomas), 5 central neurocytomas, and 1 dysembryoplastic neuroepithelial tumor (DNET) were immunostained with a mouse monoclonal antibody raised against human alpha-synuclein. Intense cytoplasmic staining, in some instances extending into the perikarya, was seen in 6 of 11 gangliogliomas, 2 of 2 anaplastic gangliogliomas, and 2 of 2 ganglioneuroblastomas. Alpha-synuclein-positive cells were usually large in size, resembled dysmorphic neurons, and were variably immunoreactive for anti-neurofilament and/or anti-synaptophysin antibodies. In contrast, central neurocytomas, gangliocytomas, and the DNET were negative for cytoplasmic alpha-synuclein expression. Our findings indicate that alpha-synuclein is expressed within the neuronal component of mixed tumors of the CNS displaying more than 1 histophenotype, and/or showing different degrees of anaplasia. Based on currently available data, we conclude that cytoplasmic alpha-synuclein expression is a marker of maturing neurons in these tumors.

Multidisciplinary approach to traumatic intracranial aneurysms secondary to shotgun and handgun wounds

BACKGROUND

Traumatic intracranial aneurysms (TICAs) may develop following gunshot injuries to the head. Management of these lesions often combines various aspects of microneurosurgical and endovascular techniques to safely repair or obliterate vessel defects.

METHODS

We reviewed our experience over the last 18 years and identified five cases of intracranial aneurysms following gunshot and handgun wounds that were treated surgically and/or endovascularly.

RESULTS

All patients had successful obliteration of their lesions using a variety of therapeutic modalities aimed at preserving neurologic function while at the same time eliminating the aneurysm from the circulation.

CONCLUSION

Both microneurosurgery and endovascular surgery have important roles to play in the management of TICAs. In some cases, both methods can be combined to eliminate lesions and maximize patient recovery in a safe, efficient, and effective fashion.

Radiation change versus recurrent astrocytoma: diagnostic utility of the proliferation index?

Differentiation of recurrent glioma from radiation damage can be a challenge to neurologists, neurosurgeons, neuroradiologists, and even neuropathologists. We hypothesized that by evaluating sections of recurrent lesions with proliferation markers we might objectively differentiate between radiation damage gliosis and recurrent astrocytoma. We compared the labeling indices of radiation damage and recurrent neoplasm immunohistochemically, using an antibody to MIB-1, a monoclonal antibody to the Ki-67 proliferation marker. Five of the six recurrent neoplasms were gliomas; four these were astrocytic tumors. In most cases, the MIB-1 LI of radiation damage was < 1% and the LI of recurrent neoplasm was > 3%, with pertinent exceptions. We discuss our findings and their possible interpretation.

Death due to a ruptured berry aneurysm in a 3.5-year-old child

Berry aneurysms in childhood are rare and have certain characteristics that distinguish them from their adult counterparts. A case of death caused by a ruptured berry aneurysm in a child is presented, and the topic is reviewed.

Glial tumors in the MNU rat model: induction of pure and mixed gliomas that do not require typical missense mutations of p53

Gliomas were induced in adult male Sprague-Dawley rats by continuous exposure to 100 ppm of N-nitrosmethylurea (MNU) in drinking water. Latency periods for such tumors were 20 and 50 weeks following completion of exposure intervals of 20, 15, and 10 weeks, respectively. Based on histomorphology and the pattern of GFAP immunoreactivity, a large percentage of MNU-induced tumors (>40%) were anaplastic mixed gliomas, having both neoplastic astrocytic and oligodendroglial components. Typical oligodendrogliomas and astrocytomas also occurred less frequently. Unlike the majority of tumors induced by ethylnitrosourea (ENU), MNU yielded glial tumors that did not express synaptophysin. Anaplastic mixed gliomas and glioblastoma multiforme (GBMs) had no missense p53 mutations in the commonly mutated exons 4 through 8 and did not overexpress wild-type p53, suggesting that MNU-induced oncogenesis in rat brain tumors may not require inactivation/alteration of the p53 tumor suppressor gene. The K-ras gene was also analyzed and found to have no activating mutations in brain tumors. This model is suitable for studying genetic events leading to the majority of gliomas that apparently express functional p53.

Correlation of bcl-2, p53, and MIB-1 expression with ependymoma grade and subtype

In this study, we report our results on the proliferative activity of ependymomas as determined by MIB-1 (also known as Ki-67) immunohistochemical analysis, and we compare our results with those obtained by immunolabeling with monoclonal antibodies to p53 and bcl-2 proteins to assess whether expression correlated with ependymoma subtype or tumor grade. The study included 4 myxopapillary ependymomas (Grade I of the World Health Organization [WHO] scale), 10 subependymomas (WHO Grade I), 17 ependymomas (WHO Grade II), 2 papillary ependymomas (WHO grade II), and 4 anaplastic ependymomas (WHO Grade III). The MIB-1 proliferation index was significantly higher in tumors diagnosed as anaplastic ependymoma (P < .001), with a moderate level of correlation (Kendall's tau-b = 0.557, asymptotic standard error = 108). In addition, one ependymoma (WHO Grade II) not considered overtly anaplastic by routine histologic criteria showed a high MIB-1 labeling index, suggesting that the MIB-1 proliferation index might be a more objective indicator of tumor grade. The remaining WHO Grade I and Grade II ependymomas showed low proliferative activity. bcl-2 oncoprotein expression was identified in all of the four myxopapillary and in both papillary ependymomas. An additional observation was the correlation of p53 expression with increasing WHO grade. These data suggest that high MIB-1 and p53 immunolabeling might be objective indicators of high grade in ependymomas that do not otherwise meet routine histologic criteria for high-grade ependymoma. Subsequent clinicopathologic analyses will be important in assessing whether these markers are useful as independent predictors of survival.

Bad news and good news: what the dentist needs to know about transmissible spongiform encephalopathies

Since reports of the "mad cow disease" epidemic in Great Britain erupted in the international press, sensational and intimidating articles about the risk that bovine spongiform encephalopathy and related diseases may pose to humans have appeared. The bad news is that compelling scientific evidence suggests so-called prion disease can and has infected humans, although the overall risk appears to be low. Furthermore, at present, there is no reliable antemortem diagnosis, specific treatment, or vaccine to prevent the disease. The agent thought to be responsible for this unusual class of disease is a rogue protein (called a prion) that, unlike all other agents known to cause infectious disease, contains neither DNA nor RNA. According to a popular hypothesis, normal membrane-associated prion proteins undergo conformational changes that can cause disease. The "bad" prion forms cause holes or a spongy appearance in the brain in all disease variants, hence the generic designation of spongiform encephalopathy. The good news is that risk for exposure to prion disease is exceedingly remote in the dental practice and that current universal infection control procedures are probably sufficient.

Supratentorial giant cell ependymoma: a case report

Ependymomas are neoplasms of the central nervous system that are capable of demonstrating remarkably heterogeneous histologic features. These tumors originate from ependymal cells lining the ventricles, the choroid plexus, the central canal of the spinal cord, and the filum terminale, so they are therefore seen throughout the neuraxis. We describe the case of a 26-year-old man who experienced a 3-week history of right-sided numbness and a 1-week history of worsening bifrontal headache. Computed tomographic scanning and magnetic resonance imaging of his head demonstrated an irregularly enhancing mass involving the left medial frontal lobe, with extension across the corpus callosum and expansion into the body and atrium of the left lateral ventricle. Histologic, immunohistochemical, and electron microscopic findings were consistent with an anaplastic ependymoma. Unique to this neoplasm was the presence of multiple tumor giant cells. The presence of pleomorphic tumor giant cells is a characteristic feature of the subependymal giant cell astrocytoma, and it is also commonly seen in pleomorphic xanthoastrocytoma and glioblastoma multiforme. Bizarre giant cells were recently described in two filum terminale ependymomas. This report presents the first case of a supratentorial giant cell ependymoma with anaplastic features.

Primary epithelioid hemangioendothelioma of the clivus

We describe the clinical, radiologic, and pathologic features of a primary intracranial hemangioendothelioma arising in the clivus in a 38-year-old female, emphasizing the importance of including this rare entity in the differential diagnosis of tumors arising at the base of the skull. To our knowledge, this is the first reported case of a clival hemangioendothelioma. Aside from its unusual location, this case is also notable for its apparent rapid growth and mixed epithelioid-spindle cell morphology. Appropriate neuroimaging studies may offer crucial information, ensuring that this uncommon entity is included in the differential diagnosis of a clival mass.

Hormone receptor immunoreactivity in hemangioblastomas and clear cell renal cell carcinomas

Several primary central nervous system (CNS) neoplasms, including meningiomas, spinal cord ependymomas, and acoustic nerve schwannomas, express hormone receptors. In the present study, we investigated hormone receptor immunoreactivity in hemangioblastomas on the basis of recent reports of these tumors complicating pregnancy. We also evaluated cases of renal cell carcinoma (RCC) metastatic to the CNS, hypothesizing that estrogen receptor (ER), progesterone receptor (PR), or androgen receptor (AR) immunoreactivity might help to distinguish between these histologically similar neoplasms. Immunohistochemical analysis for ERs, PRs, and ARs was performed on paraffin-embedded sections of 27 hemangioblastomas, 12 primary clear cell RCCs, and 5 clear cell RCCs metastatic to the CNS. All of the hemangioblastomas demonstrated PR immunoreactivity, whereas 10 of 12 primary RCCs were negative. In addition, four of the five metastatic RCC were PR positive. All but one primary RCC were ER negative. AR immunoreactivity was seen in three hemangioblastomas, five primary RCCs, and one metastatic RCC. Although hormone receptor immunoreactivity was unable to distinguish between hemangioblastoma and clear cell RCC metastatic to the CNS, the identification of PR immunoreactivity in hemangioblastomas is a new finding that might have adjuvant therapy treatment implications.

Frequency of unilateral and bilateral mesial temporal sclerosis in primary and secondary epilepsy: a forensic autopsy study

Controversy exists regarding the pathogenetic relationship of mesial temporal sclerosis (MTS) to epileptogenesis. Some investigators view hippocampal sclerosis as the primary cause of temporal lobe epilepsy, whereas others interpret the changes to be the result of chronic seizure activity. The present autopsy-based study attempts to clarify the etiologic relationship between mesial temporal sclerosis and epilepsy. To investigate the assumption that bilateral MTS is more likely to be the result of chronic seizure activity associated with a seizure focus outside the hippocampus, two subject groups were identified. The first group comprised 43 patients who had no extrahippocampal pathology and were classified as having primary epilepsy. The second group comprised 35 patients who, had identifiable extrahippocampal pathology and were classified as having secondary epilepsy. Fifteen of the 35 cases of secondary epilepsy also had MTS; seven of these were unilateral and eight were bilateral. Of the 43 cases with primary epilepsy, only one had MTS, and it was unilateral. Significantly more cases of primary epilepsy than secondary epilepsy had no MTS (p < 0.001), suggesting that both unilateral and bilateral forms of MTS occur with greater frequency in subjects with seizure foci outside the hippocampus. These results also suggest that unilaterality of MTS does not exclude an extrahippocampal cause.

Human telomerase RNA expression and MIB-1 (Ki-67) proliferation index distinguish hemangioblastomas from metastatic renal cell carcinomas

Hemangioblastomas are low-grade, capillary rich neoplasms of the cerebellum and spinal cord that can occur sporadically or in the setting of Von Hippel-Lindau syndrome. The present study analyzed the utility of proliferation potential in differentiating hemangioblastoma from RCC metastatic to the central nervous system using a MIB-1 (Ki-67) labeling index and assessment of expression of the RNA component of telomerase. Immunohistochemical analysis for epithelial membrane antigen (EMA) and MIB-1 was performed on paraffin-embedded sections of 27 hemangioblastomas and 5 RCC metastatic to the central nervous system. All but one hemangioblastoma demonstrated low or negative MIB-1 immunoreactivity, while 4 of 5 RCC metastases had moderate or high labeling indices. Telomerase RNA expression was assessed in 10 hemangioblastomas and in all 5 metastatic RCC by in Situ hybridization. All 10 hemangioblastomas demonstrated a lack of expression of telomerase RNA, while all 5 metastatic RCCs showed moderate to strong expression. Our results suggest that the MIB-1 labeling index is useful in differentiating hemangioblastoma from metastatic RCC and assessment of telomerase expression can also provide novel information on the difference in growth potential of these tumors.

Rosenthal fibers and eosinophilic granular bodies in a classic acoustic schwannoma

We describe unique features seen in a case of classic acoustic schwannoma. In the central portion of the tumor, abundant Rosenthal fibers and occasional eosinophilic granular bodies were present. Rosenthal fibers are homogeneous eosinophilic structures commonly seen in central nervous system lesions, such as pilocytic astrocytoma, or in the gliotic tissues adjacent to slowly growing neoplasms and some congenital malformations. Eosinophilic granular bodies are also structural markers of slow-growing, well-differentiated neuroglial neoplasms, such as pleomorphic xanthoastrocytoma, ganglion cell tumors, and pilocytic astrocytoma. To the best of our knowledge, however, these two structures have never before been described in schwannomas.

Expression of telomerase RNA component correlates with the MIB-1 proliferation index in ependymomas

Although there is general agreement that certain morphologic subtypes of ependymoma are benign, the biologic behavior of other ependymal neoplasms is poorly understood and not clearly related to conventional histopathologic criteria. The absence of universally accepted standards has prompted the search for more objective biologic markers. Telomerase is an RNA-containing enzyme associated with immortality in proliferating stem cells and many tumors. We investigated the proliferative activity of 26 ependymomas as determined by MIB-1 immunolabeling and compared the results with the in situ expression of human telomerase RNA (hTR) and WHO tumor grade. The study included 9 WHO grade I ependymomas (6 subependymomas and 3 myxopapillary ependymomas), 13 WHO grade II ependymomas, and 4 anaplastic (WHO grade III) ependymomas. The proliferation index (PI) and telomerase RNA expression were significantly increased in grade III ependymomas (p < 0.0001 for PI and p = 0.0015 for hTR). In these tumors, the PI and hTR expression were highly correlated (p = 0.0001). Of note, a single case designated grade II showed both increased proliferative activity and the highest hTR expression detected in this series of ependymal neoplasms. Our results suggest that the PI and hTR expression may be important biologic markers, independent of other histopathologic criteria of tumor grade. Future studies examining the correlation of MIB-1 cell kinetics and hTR expression with clinical parameters in selected ependymoma subtypes are needed to determine the prognostic relevance of these markers.

Nonneoplastic pineal cysts: a clinicopathologic study of twenty-one cases

Twenty-one cases of nonneoplastic pineal cyst are presented. The patients were 13 women and 8 men, with a median age of 33 years. Sixteen patients were symptomatic. Symptomatic cysts had an average size of 16.5 mm. In most cases, symptoms and signs were related to increased intracranial pressure, cerebrospinal fluid obstruction, neuroophthalmologic dysfunction, brainstem and cerebellar compression, and mental status changes. Uncommon clinical presentations in three cases were related to increased cyst size caused by hemorrhage, sudden death, and postural syncope and loss of consciousness. Imaging studies showed a uniform hypodense or hypointense, nonenhancing pineal mass with occasional peripheral calcification and associated with hydrocephalus, aqueductal compression, tectal deformity, and hemorrhage within the cavity, in decreasing order of frequency. Fourteen patients underwent open cyst resection. Histologically, the intact lesions show a unilocular or multilocular cavity, surrounded by a wall comprised of variable amounts of glial tissue, remnants of pineal gland, and an external fibrous capsule. Follow-up information showed 12 patients alive and well without recurrence between 26 and 144 postoperative months. One patient who underwent stereotactic drainage had a recurrence. One symptomatic patient who did not have surgery died suddenly of causes related to the cyst. The present study supports the role of surgical excision for the treatment of symptomatic pineal cysts to obtain adequate tissue for diagnosis and relief of symptoms. The use of histochemical and immunohistochemical studies may prove useful in the distinction of these lesions with astrocytomas and cystic pineal parenchymal tumors.

Congenital central nervous system tumors

Congenital central nervous system (CNS) tumors are a rare and diverse group of tumors with variable biological behavior depending on location and histology. This review summarizes the published literature and describes the definition, epidemiology, diagnosis and evaluation, and treatment of congenital central nervous system tumors.

Mesenchymal chondrosarcoma: a clinicopathologic and flow cytometric study of 13 cases presenting in the central nervous system

BACKGROUND

Mesenchymal chondrosarcomas arising in the central nervous system are extremely rare. Morphologic features have not been found to correlate reliably with prognosis.

METHODS

Eight intracranial and five intraspinal mesenchymal chondrosarcomas were reviewed with regard to location, treatment, and long term follow-up data. The histopathologic and immunohistochemical results, including Ki-67 nuclear staining frequency, were critically reviewed, and deoxyribonucleic acid content was analyzed by flow cytometry.

RESULTS

Microscopically, all 13 cases were remarkably similar. Immunoreactivity in the small cell component included vimentin in 100% and cytokeratin and glial fibrillary acidic protein in 25% of cases. S-100 immunoreactivity was noted in the cartilaginous component of 100% of cases, and in rare cells in the small cell component along the interface. Flow cytometry of the eight tumors studied revealed a diploid pattern in six, aneuploidy in two, and a wide range of S-phase fractions (0-36.5%).

CONCLUSIONS

Review of the literature and the findings of the current series indicates that mesenchymal chondrosarcomas presenting in the brain and spinal cord pursue a progressive course that correlates most reliably with extent of surgical resection. This limited retrospective study also suggests that survival may be shorter for those patients with a high S-phase fraction and a high Ki-67 staining frequency.

Infrequency of p53 gene mutations in ependymomas

Ependymomas, which comprise 5% of central nervous system tumors, have not been extensively characterized genetically. The p53 tumor suppressor gene is frequently mutated in human cancer, and is important in the pathogenesis of other central nervous system (CNS) tumors. Chromosomal DNA corresponding to the p53 tumor suppressor gene was amplified by the polymerase chain reaction (PCR) from 31 archival ependymoma specimens. DNA was screened for the presence of p53 mutations by single strand conformational polymorphism (SSCP) analysis; samples with altered mobility were further tested for the presence of mutation by direct DNA sequence analysis. Of the 31 ependymomas tested, one contained a detectable DNA sequence change in the p53 gene. Sequencing revealed a silent mutation in exon 6, at codon 213, which represents a known p53 sequence polymorphism. These finding suggest that in contrast to many other human cancers, p53 mutation is not important in the pathogenesis or progression of ependymomas.

Mesenchymal chondrosarcoma of the cauda equina

Primary central nervous system mesenchymal chondrosarcomas are extremely rare tumors composed of primitive mesenchymal cells punctuated by islands of cartilage in various stages of differentiation. Although there are isolated reports of tumors arising in the spinal dura, to our knowledge extraskeletal mesenchymal chondrosarcoma localized to the cauda equina has not been reported in the literature. We present an unusual case of a mesenchymal chondrosarcoma involving the nerve roots of the cauda equina. The clinical, pathological and neuroimaging features are reviewed and discussed.

Tumors of pineal parenchymal cells: a correlation of histological features, including nucleolar organizer regions, with survival in 35 cases

We studied 35 parenchymal neoplasms arising in the pineal gland, including 11 pineoblastomas, 21 pineocytomas, and three mixed pineocytoma-pineoblastomas. Pineoblastomas were most commonly found in children (mean age, 12.6 years). The median postsurgical length of survival for seven patients, including five with remote metastases, with fatal outcome was 24 months. The 21 pineocytomas were found in older individuals (mean age, 26.8 years). Four patients with pineocytoma died; two before surgery and two in the immediate postoperative period. The remaining 17 patients survived for intervals between 6 and 118 months after surgery. Two mixed pineocytoma-pineoblastomas were found in infants who died a few months after biopsy, whereas a third patient, an adult, was alive at 46 months after excision and irradiation. Both pineoblastoma and pineocytoma exhibited variable immunoreactivity to neurofilament proteins, synaptophysin, glial fibrillary acidic protein, S-100 protein, retinal-S antigen, and rhodopsin; the highest percentages of positive cells stained with synaptophysin. Three pineocytomas exhibited ganglionic differentiation and two of them also showed a glial component. Prognosis could not be correlated with the degree of divergent differentiation. Comparison of silver-stained nucleolar organizer region (AgNOR) counts between pineoblastomas and pineocytomas suggests that the former are more actively proliferative than the latter, with mixed pineocytoma-pineoblastoma showing intermediate activity. There was no correlation between AgNOR score and prognosis within the three tumor groups.

Optic pathway glioma infiltrating into somatostatinergic pathways in a young boy with gigantism. Case report

The authors report gigantism in a 16-month-old boy with an extensive optic pathway glioma infiltrating into somatostatinergic pathways, as revealed by magnetic resonance imaging and immunocytochemical studies. Stereotactic biopsies of areas showing hyperintense signal abnormalities on T2-weighted images in and adjacent to the involved visual pathways provided rarely obtained histological correlation of such areas. The patient received chemotherapy, which resulted in reduction of size and signal intensity of the tumor and stabilization of vision and growth velocity.

Cerebellopontine angle masses: radiologic-pathologic correlation

The cerebellopontine angle cistern is a cerebrospinal fluid-filled space bound by the pons, cerebellum, and petrous temporal bone. Masses in this region are readily identified on cross-sectional images. Differential diagnosis of masses in this region can be simplified by using an algorithmic approach that combines morphologic and enhancement characteristics with established demographic data. Schwannomas are enhancing, round masses, most commonly arising from the vestibular nerve near the porus acusticus and associated with enlargement of the internal auditory canal. Meningiomas are enhancing, oval or hemispheric lesions with a broad attachment to the tentorium or petrous dura mater. Congenital epidermoid inclusion cysts are nonenhancing masses that have undulating margins, molding their shape to conform to the adjacent structures. Aneurysms without significant internal thrombus have prominent flow voids on magnetic resonance images.

Problems in the nosology of desmoplastic tumors of childhood

Several types of central nervous system tumors primarily consisting of a combination of astrocytes and fibrocollagen and occurring most commonly in infancy have been separately introduced as new diagnostic entities. The names applied to these tumors have included 'gliofibroma', 'desmoplastic cerebral astrocytoma', and 'desmoplastic infantile ganglioglioma', a group containing ganglion cells as well as the astrocytes and mesenchymal tissue. We studied a gliofibroma arising in the fourth ventricle of a 6-month-old infant and three examples of desmoplastic cerebral astrocytoma in infants utilizing routine histological and immunocytochemical methods, and at the ultrastructural level in two tumors. In view that the desmoplastic cerebral astrocytomas contain poorly differentiated neuroepithelial cells and rarely, a ganglion cell, we suggest that gliofibroma and desmoplastic astrocytoma are basically the same entity and that the desmoplastic infantile ganglioglioma is a variant containing primitive or mature ganglion cells.

Pineal region masses: differential diagnosis

Most pineal region masses are malignant germ cell neoplasms that occur in young male patients. The most common is a germinoma, which is a homogeneous mass with signal intensity and attenuation similar to those of gray matter; the mass engulfs a densely calcified pineal gland. Teratomas are multilocular heterogeneous masses containing lipid areas. Other types of pineal region masses include choriocarcinoma, endodermal sinus tumor, and embryonal carcinoma. Pineal parenchymal neoplasms are usually either pineocytomas or pineoblastomas, which may "explode" preexisting pineal calcifications. Unlike the germinomas, they have no sexual predilection and may be seen in patients who are 20 years of age or older. Although the correct histologic diagnosis may be suggested with a careful evaluation of the morphologic features, attenuation, and signal intensity characteristics, very few of these tumors have a truly pathognomonic imaging pattern. Thus, histologic verification is necessary for most pineal region masses that appear to be neoplastic.