Morphology-based molecular classification of spinal cord ependymomas using deep neural networks.

Based on DNA-methylation, ependymomas growing in the spinal cord comprise two major molecular types termed spinal (SP-EPN) and myxopapillary ependymomas (MPE(-A/B)), which differ with respect to their clinical features and prognosis. Due to the existing discrepancy between histomorphogical diagnoses and classification using methylation data, we asked whether deep neural networks can predict the DNA methylation class of spinal cord ependymomas from hematoxylin and eosin stained whole-slide images. Using explainable AI, we further aimed to prospectively improve the consistency of histology-based diagnoses with DNA methylation profiling by identifying and quantifying distinct morphological patterns of these molecular ependymoma types. We assembled a case series of 139 molecularly characterized spinal cord ependymomas (nMPE = 84, nSP-EPN = 55). Self-supervised and weakly-supervised neural networks were used for classification. We employed attention analysis and supervised machine-learning methods for the discovery and quantification of morphological features and their correlation to the diagnoses of experienced neuropathologists. Our best performing model predicted the DNA methylation class with 98% test accuracy and used self-supervised learning to outperform pretrained encoder-networks (86% test accuracy). In contrast, the diagnoses of neuropathologists matched the DNA methylation class in only 83% of cases. Domain-adaptation techniques improved model generalization to an external validation cohort by up to 22%. Statistically significant morphological features were identified per molecular type and quantitatively correlated to human diagnoses. The approach was extended to recently defined subtypes of myxopapillary ependymomas (MPE-(A/B), 80% test accuracy). In summary, we demonstrated the accurate prediction of the DNA methylation class of spinal cord ependymomas (SP-EPN, MPE(-A/B)) using hematoxylin and eosin stained whole-slide images. Our approach may prospectively serve as a supplementary resource for integrated diagnostics and may even help to establish a standardized, high-quality level of histology-based diagnostics across institutions-in particular in low-income countries, where expensive DNA-methylation analyses may not be readily available.

Diffuse midline gliomas, H3 K27M-mutant are associated with less peritumoral edema and contrast enhancement in comparison to glioblastomas, H3 K27M-wildtype of midline structures.

PURPOSE: The entity 'diffuse midline glioma, H3 K27M-mutant (DMG)' was introduced in the revised 4th edition of the 2016 WHO classification of brain tumors. However, there are only a few reports on magnetic resonance imaging (MRI) of these tumors. Thus, we conducted a retrospective survey focused on MRI features of DMG compared to midline glioblastomas H3 K27M-wildtype (mGBM-H3wt). METHODS: We identified 24 DMG cases and 19 mGBM-H3wt patients as controls. After being retrospectively evaluated for microscopic evidence of microvascular proliferations (MVP) and tumor necrosis by two experienced neuropathologists to identify the defining histological criteria of mGBM-H3wt, the samples were further analyzed by two experienced readers regarding imaging features such as shape, peritumoral edema and contrast enhancement. RESULTS: The DMG were found in the thalamus in 37.5% of cases (controls 63%), in the brainstem in 50% (vs. 32%) and spinal cord in 12.5% (vs. 5%). In MRI and considering MVP, DMG were found to be by far less likely to develop peritumoral edema (OR: 0.13; 95%-CL: 0.02-0.62) (p = 0.010). They, similarly, were associated with a significantly lower probability of developing strong contrast enhancement compared to mGBM-H3wt (OR: 0.10; 95%-CL: 0.02-0.47) (P = 0.003). CONCLUSION: Despite having highly variable imaging features, DMG exhibited markedly less edema and lower contrast enhancement in MRI compared to mGBM-H3wt. Of these features, the enhancement level was associated with evidence of MVP.

Comprehensive analysis of diverse low-grade neuroepithelial tumors with FGFR1 alterations reveals a distinct molecular signature of rosette-forming glioneuronal tumor.

The FGFR1 gene encoding fibroblast growth factor receptor 1 has emerged as a frequently altered oncogene in the pathogenesis of multiple low-grade neuroepithelial tumor (LGNET) subtypes including pilocytic astrocytoma, dysembryoplastic neuroepithelial tumor (DNT), rosette-forming glioneuronal tumor (RGNT), and extraventricular neurocytoma (EVN). These activating FGFR1 alterations in LGNET can include tandem duplication of the exons encoding the intracellular tyrosine kinase domain, in-frame gene fusions most often with TACC1 as the partner, or hotspot missense mutations within the tyrosine kinase domain (either at p.N546 or p.K656). However, the specificity of these different FGFR1 events for the various LGNET subtypes and accompanying genetic alterations are not well defined. Here we performed comprehensive genomic and epigenomic characterization on a diverse cohort of 30 LGNET with FGFR1 alterations. We identified that RGNT harbors a distinct epigenetic signature compared to other LGNET with FGFR1 alterations, and is uniquely characterized by FGFR1 kinase domain hotspot missense mutations in combination with either PIK3CA or PIK3R1 mutation, often with accompanying NF1 or PTPN11 mutation. In contrast, EVN harbors its own distinct epigenetic signature and is characterized by FGFR1-TACC1 fusion as the solitary pathogenic alteration. Additionally, DNT and pilocytic astrocytoma are characterized by either kinase domain tandem duplication or hotspot missense mutations, occasionally with accompanying NF1 or PTPN11 mutation, but lacking the accompanying PIK3CA or PIK3R1 mutation that characterizes RGNT. The glial component of LGNET with FGFR1 alterations typically has a predominantly oligodendroglial morphology, and many of the pilocytic astrocytomas with FGFR1 alterations lack the biphasic pattern, piloid processes, and Rosenthal fibers that characterize pilocytic astrocytomas with BRAF mutation or fusion. Together, this analysis improves the classification and histopathologic stratification of LGNET with FGFR1 alterations.

Intradural Extramedullary Nonconus Nonfilum Spinal Ependymomas: Report of a Rare Variant and Newer Insights into Their Histogenesis with Proposal of a Classification Scheme and a Management Algorithm Based on a Review of Literature.

BACKGROUND: Ependymomas are common intramedullary spinal tumors but there are scattered reports of this tumor presenting with exophytic growth patterns masquerading as intradural extramedullary (IDEM) tumors. Such IDEM ependymomas are seldom suspected preoperatively and it is only during surgery that their existence is revealed. Little is known of such rare growth patterns of an otherwise common intramedullary spinal cord tumor, their characteristics, and their management considerations. METHODS: We present a case of an exophytic dorsal ependymoma with a stalk like attachment to the spinal cord and the surgical management in a 24-year old woman. An extensive literature search was carried out on all prominent databases to find out similar cases reported earlier. We excluded filum/conus ependymoma, purely extradural spinal ependymoma as well as the extraspinal ependymomas. Details of each case reported before were obtained and tabulated. RESULTS: IDEM ependymomas have been reported in 54 patients so far, including the present case. Four patterns of growth emerged from the literature review: intramedullary ependymoma with exophytic component (group I, n = 9), exophytic IDEM ependymoma without intramedullary component (group II, n = 6), IDEM ependymoma arising from nerve roots (group III, n = 7), and pure IDEM ependymoma (group IV, n = 32). Except in group I, IDEM ependymoma affects females more frequently, without any specific age predilection. Thoracic spinal cord/canal is the most common location across all groups. Multifocal disease, craniospinal dissemination, and recurrences tend to be maximum in group IV. CONCLUSIONS: IDEM ependymomas are more common in thoracic segment of the cord and broadly divisible into 4 subgroups. We suggest a subpial origin of group II IDEM ependymomas. We also advocate proliferation index estimation in grade II ependymomas to enable formulation of an optimal management plan.

Impact of H3.3 K27M Mutation on Prognosis and Survival of Grade IV Spinal Cord Glioma on the Basis of New 2016 World Health Organization Classification of the Central Nervous System.

BACKGROUND: Spinal cord glioma grade IV is a rare, diffuse midline glioma. H3 K27M-mutant was classified in a different entity in the 2016 World Health Organization (WHO) classification recently. No reports about prognosis of spinal cord glioma grade IV are available yet. OBJECTIVE: To analyze the prognostic factors for spinal cord glioma grade IV. METHODS: Twenty-five patients with spinal cord glioma of grade IV who underwent surgery in a single institute were selected. All grade IV spinal cord glioma histologically confirmed as glioblastoma or "diffuse midline glioma with H3 K27M-mutant" by the 2016 WHO classification of the central nervous system were included. Basic demographics, treatment modalities, and pathological tumor molecular profiles were investigated for prognosis. RESULTS: Mean age was 39.1 yr; male to female ratio was 18 : 7. Tumor was located in thoracic cord (53.3%), cervical cord (40%), and lumbar area (6.7%). Median overall survival was 37.1 mo; median disease-free survival was 18.5 mo. Treatment modality showed no statistical difference. Only K27M profile showed significant prognostic value, 20 patients (80%) showed K27M mutation positive, K27M mutation patients showed longer overall survival (40.07 mo) than K27M negative patients (11.63 mo, P < .0001), and disease-free survival (20.85 vs 8.72 mo, P = .0241). CONCLUSION: This study is the first and largest report of the prognosis of primary spinal cord grade IV glioma using the new WHO classification. This study reported survival analysis and prognostic factors, and revealed that H3.3 K27M mutation is not a major poor prognostic factor. Further studies to explore K27M mutations needed for risk stratification and therapy optimization.

Acute Surgical Risk Profile of Intramedullary Spinal Cord Tumor Resection in Pediatric Patients: A Pediatric National Surgical Quality Improvement Program Analysis.

OBJECTIVE: The purpose of the present study was to characterize the acute (30-day) surgical risk profile of pediatric patients undergoing surgical resection of intramedullary spinal cord tumors (IMSCTs). METHODS: Preoperative factors were collected from the Pediatric American College of Surgeons National Surgical Quality Improvement Program database for patients identified by Current Procedural Terminology codes for laminectomy and International Classification of Diseases codes for IMSCTs from 2012 to 2016. The postoperative outcomes were compared by tumor location and type. RESULTS: The mean age of the 139 patients meeting all inclusion criteria was 8.7 years, with a male predominance (58.7%). The cervical and thoracic IMSCT populations had worst preoperative health status, as indicated by American Society of Anesthesiologists class, and a greater proportion of malignant tumors compared with the lumbar IMSCT population. No patient died; 8.6% of the patients were readmitted, and 6.5% required reoperation. Of the 12 readmissions, 8 were required for patients with malignant tumors. The patients with cervical IMSCTs returned to the operating room at a significantly greater rate than did the thoracic and lumbar IMSCT populations. Two common reasons for reoperation in the cervical population were issues related to respiration and hydrocephalus management. The complications included 13 cases of infection, 6 of urinary tract infection, and 5 cases of surgical site infection. CONCLUSIONS: Resection of IMSCTs in the pediatric population is a relatively low-risk procedure in terms of acute surgical complications. However, surgeons operating in the cervical spine should be aware of the increased risk of reoperation, in particular as it pertains to respiratory issues and hydrocephalus.

Various shades of red-a systematic analysis of qualitative estimation of ALA-derived fluorescence in neurosurgery.

5-Aminolevulinic acid (5-ALA)-fluorescence-guided resection is well established in many neuro-oncologic centers. Different classifications of 5-ALA-induced fluorescence have been reported. The aim of the systematic analysis was to evaluate the frequency of graduations, definitions, and designations of 5-ALA-induced fluorescence qualities. A systematic database search of PubMed was performed to identify studies reporting (1) on 5-ALA fluorescence-guided either spinal or cranial surgery, (2) on qualitative estimation and/or categorization of 5-ALA-induced fluorescence, (3) in English, and (4) were published as peer-reviewed original studies. Totally, 93 studies were identified. Different classification systems of 5-ALA-induced fluorescence were found. Over 60 % of the included studies used a dichotomized categorization of 5-ALA-induced fluorescence and 27.5 % of studies distinguished two different intensities of 5-ALA fluorescent tissue in addition to non-fluorescing tissue. More than 50 % of studies explicitly defined criteria for categorization of 5-ALA-induced fluorescence. The major limitation of the present analysis might be that it mainly comprises data from retrospective, uncontrolled, non-randomized trials. However, a precise definition of each 5-ALA-induced fluorescence quality is essential. Although dichotomized classification is the most common and simple graduation system, it may not be suitable for every clinical or scientific task. A three-level 5-ALA-induced fluorescence classification with precise definition of each fluorescence quality and their correlation with histological features would be more useful and reproducible in these cases.

New classification of spinal lipomas based on embryonic stage.

OBJECTIVE Spinal lipomas are generally thought to occur as a result of failed primary neurulation. However, some clinical features cannot be explained by this theory. The authors propose a novel classification of spinal lipomas based on embryonic changes seen during primary and secondary neurulation. METHODS A total of 677 patients with occult spinal dysraphism underwent 699 surgeries between August 2002 and May 2015 at the National Center for Child Health and Development and Tokyo Metropolitan Children's Medical Center. This group of patients had 378 spinal lipomas, including 119 conus spinal lipomas, 27 lipomyelomeningoceles, and 232 filum lipomas, which the authors classified into 4 types based on neural tube formation during embryonic development. Type 1 is defined as pure primary neurulation failure; Type 2 ranges from primary to secondary neurulation failure; Type 3 consists of secondary neurulation failure (early phase); and Type 4 is defined as secondary neurulation failure (late phase). The authors also review embryogenesis in secondary neurulation and analyze the clinical utility of the new classification. RESULTS There were 55 Type 1 spinal lipomas, 29 Type 2, 62 Type 3, and 232 Type 4. All filum lipomas fell into the Type 4 spinal lipoma category. Association with anorectal and/or sacral anomalies was seen in none of the Type 1 cases, 15 (52%) of Type 2, 35 (56%) of Type 3, and 31 (13%) of Type 4. Urogenital anomalies were observed in none of the Type 1 or Type 2 cases, 1 (2%) of Type 3, and 28 (12%) of Type 4. Anomaly syndromes were present in none of the Type 1 cases, 6 (21%) of Type 2, 3 (5%) of Type 3, and 16 (7%) of Type 4. Associated anomalies or anomaly syndromes were clearly observed only for Type 2-4 spinal lipomas encompassing failed secondary neurulation. Radical resection was feasible for Type 1 spinal lipomas. CONCLUSIONS Secondary neurulation of the spinal cord gives rise to the conus medullaris and filum terminale, which are often involved in spinal lipomas. Formation of spinal lipomas seems to be a continuous process overlapping primary and secondary neurulation in some cases. Association with other anomalies was higher in Type 2-4 spinal lipomas, which included failed secondary neurulation, than in Type 1 lipomas, with failed primary neurulation. On the other hand, radical resection was indicated for Type 1, but not for Type 2, spinal lipomas. The new classification of spinal lipomas based on embryonic stage has the potential for clinical use and agrees well with both clinical and surgical findings. The classification proposed here is still preliminary. Further studies and verification are necessary to establish its clinical utility.

The genetic basis of intradural spinal tumors and its impact on clinical treatment.

Genetic alterations in the cells of intradural spinal tumors can have a significant impact on the treatment options, counseling, and prognosis for patients. Although surgery is the primary therapy for most intradural tumors, radiochemothera-peutic modalities and targeted interventions play an ever-evolving role in treating aggressive cancers and in addressing cancer recurrence in long-term survivors. Recent studies have helped delineate specific genetic and molecular differences between intradural spinal tumors and their intracranial counterparts and have also identified significant variation in therapeutic effects on these tumors. This review discusses the genetic and molecular alterations in the most common intradural spinal tumors in both adult and pediatrie patients, including nerve sheath tumors (that is, neurofibroma and schwannoma), meningioma, ependymoma, astrocytoma (that is, low-grade glioma, anaplastic astrocytoma, and glioblastoma), hemangioblastoma, and medulloblastoma. It also examines the genetics of metastatic tumors to the spinal cord, arising either from the CNS or from systemic sources. Importantly, the impact of this knowledge on therapeutic options and its application to clinical practice are discussed.

Feasibility of a novel diagnostic chart of intramedullary spinal cord tumors in magnetic resonance imaging.

STUDY DESIGN: Retrospective chart review. OBJECTIVES: Each type of intramedullary spinal cord tumor (IMSCT) has specific anatomical and pathological features visible on magnetic resonance (MR) imaging. The purpose of this study was to investigate the accuracy of preoperative IMSCT diagnosis using our diagnostic chart of tumor-specific MR imaging findings. SETTING: Hamamatsu, Japan. METHODS: From 2009 to 2013, 28 consecutive patients with IMSCT who underwent surgery in our university hospital were included in this study. There were 17 men and 11 women with an average age of 49 years (12-81). The pathological diagnoses were hemangioblastoma (12), ependymoma (11), astrocytoma (4) and squamous cell carcinoma (1). Tumor-specific MR imaging findings were as follows: ependymoma ((a) spinal cord swelling, (b) contrast effect with necrosis, (c) tumor in the center of the spinal cord), hemangioblastoma ((a) spinal cord swelling, (b) homogeneous contrast effect) and astrocytoma ((a) spinal cord swelling, (b) contrast effect is either, (c) eccentric tumor). Based on these features, we generated a diagnostic chart to investigate the MR imaging diagnosis accuracy for IMSCTs. RESULTS: The accuracy of preoperative diagnosis was 89% (25/28 cases). Correct diagnoses were made in 100% of hemangioblastomas (12/12 cases), 90% of ependymomas (9/11 cases) and 100% of astrocytomas (4/4 cases). CONCLUSIONS: Different types of IMSCTs exhibit unique MR imaging characteristics. These features can be used to preoperatively diagnose IMSCTs with high accuracy.

[Clinical classification and surgical management of cervicothoracic intraspinal lipomas].

OBJECTIVE: To explore the clinical classification and surgical management of cervicothoracic intraspinal lipomas. METHODS: A total of 22 patients with cervicothoracic intraspinal lipomas were analyzed retrospectively with regards to clinical manifestations, radiographic features, intraoperative findings, surgical techniques and follow-ups. RESULTS: Total (n = 4), subtotal (n = 7) and partial (n = 11) resection was performed. Long-term neurological outcomes were evaluated by modified McCormick classification scheme. Their symptoms improved (n = 15), unchanged (n = 3) and deteriorated (n = 4). And cervicothoracic intraspinal lipomas could be classified into extradural, transitional, chaotic and secondary intramedullary groups. CONCLUSION: Different groups of cervicothoracic intraspinal lipomas vary in the degree of resection and surgical efficacy. Total resection may be performed on most extradural lipomas. The surgical objective of transitional lipomas is decompression. Chaotic and secondary intramedullary lipomas should target effective resection to avoid neurological function injury. Intraoperative use of laser facilitates tumor resection. Intraoperative electrophysiological monitoring protects spinal cord.

Posterior fossa and spinal gangliogliomas form two distinct clinicopathologic and molecular subgroups.

BACKGROUND: Gangliogliomas are low-grade glioneuronal tumors of the central nervous system and the commonest cause of chronic intractable epilepsy. Most gangliogliomas (>70%) arise in the temporal lobe, and infratentorial tumors account for less than 10%. Posterior fossa gangliogliomas can have the features of a classic supratentorial tumor or a pilocytic astrocytoma with focal gangliocytic differentiation, and this observation led to the hypothesis tested in this study - gangliogliomas of the posterior fossa and spinal cord consist of two morphologic types that can be distinguished by specific genetic alterations. RESULTS: Histological review of 27 pediatric gangliogliomas from the posterior fossa and spinal cord indicated that they could be readily placed into two groups: classic gangliogliomas (group I; n = 16) and tumors that appeared largely as a pilocytic astrocytoma, but with foci of gangliocytic differentiation (group II; n = 11). Detailed radiological review, which was blind to morphologic assignment, identified a triad of features, hemorrhage, midline location, and the presence of cysts or necrosis, that distinguished the two morphological groups with a sensitivity of 91% and specificity of 100%. Molecular genetic analysis revealed BRAF duplication and a KIAA1549-BRAF fusion gene in 82% of group II tumors, but in none of the group I tumors, and a BRAF:p.V600E mutation in 43% of group I tumors, but in none of the group II tumors. CONCLUSIONS: Our study provides support for a classification that would divide infratentorial gangliogliomas into two categories, (classic) gangliogliomas and pilocytic astrocytomas with gangliocytic differentiation, which have distinct morphological, radiological, and molecular characteristics.

Measuring the impact of the Thoracolumbar Injury Classification and Severity Score among 458 consecutively treated patients.

CONTEXT: The Thoracolumbar Injury Classification and Severity Score (TLICS) was proposed to improve injury classification and guide surgical decision-making of thoracolumbar spinal trauma (TLST), but its impact on the care of patients has not been quantified. STUDY DESIGN: Retrospective study. PATIENT SAMPLE: Analysis of 458 patients treated for TLST trauma from 2000 through 2010 at a single center. Outcome measures Neurological status - ASIA Impairment Scale (AIS), failure of conservative treatment, and surgical complications. METHODS: Clinical and radiological data were evaluated. Patients were grouped according to the period before (2000-2006) and after (2007-2010) utilization of the TLICS. RESULTS: From 2000 to 2006, 148 patients were initially treated conservatively (C) and 66 were surgically (S) treated. In the C group, the TLICS ranged from 1 to 7 (median 1; mean 1.57). In the S group, the TLICS ranged from 2 to 10 (median 2; mean 4.14). The TLICS matched treatment in 97.9% of conservatively treated patients. From 2007 to 2010, 162 patients were initially treated C and 82 were treated S. In the C group, the TLICS ranged from 1 to 4 (median 1; mean 1.48). In the S group, the TLICS ranged from 2-10 (median 4; mean 4.4). The TLICS matched treatment in 98.8% of C-treated patients. Overall, failure of C treatment occurred in nine patients; most failures (7/9) and all three missed distractive injuries occurred prior to use of the TLICS. CONCLUSIONS: After introduction of the TLICS, there was a trend towards more successful conservative treatment with fewer conversions to surgical treatment.

Intradural spinal tumours and their mimics: a review of radiographic features.

Intradural spinal tumours, although relatively uncommon, can be diagnostically challenging, and often result in significant morbidity. They can be subdivided according to their cell of origin and whether they are within the cord (intramedullary) or intradural but extramedullary in location. The differential diagnosis for masses of the cauda equina region is often considered separately. Additionally, some inflammatory processes, cysts, benign tumour-like masses and vascular malformations may mimic intradural tumours. Although in many instances, a precise preoperative diagnosis is not possible as many of the imaging findings overlap, some features may strongly suggest one diagnosis over others. This article reviews the range of intradural spinal tumours in the adult and paediatric populations, with an emphasis on pertinent imaging characteristics. An approach is provided for distinguishing tumours from lesions that mimic tumours and for narrowing the differential diagnosis according to imaging findings.

Treatment of intramedullary tumors: analysis of surgical morbidity and long-term results.

OBJECT: Surgery of intramedullary tumors is established as the treatment of choice for these challenging lesions. This study presents a detailed analysis of risk factors for surgical morbidity and data on long-term results for intramedullary tumors. METHODS: Among 1317 patients with tumors of the spinal canal treated between 1980 and 2012, 278 patients with intramedullary tumors are presented. A total of 225 of these patients underwent 246 operations for treatment of 250 tumors. The mean patient age was 41 ± 17 years (range 3 weeks to 83 years). Patients underwent follow-up through outpatient visits and questionnaires with a mean follow-up of 41 ± 53 months. Tumors were subdivided into 3 groups: displacing tumors (Type A, n = 162), infiltrating tumors (Type B, n = 80), and nonproliferating tumors (Type C, n = 8). A gross-total resection (GTR) was attempted for every tumor except for Type C lipomas. Participating surgeons were divided into 3 groups according to the number of operations they performed. Short-term results were determined for individual symptoms and the modified McCormick Scale, whereas tumor recurrence rates were calculated with Kaplan-Meier statistics. RESULTS: Overall, 83.3% of Type A tumors underwent GTR compared with 22.5% of Type B and none in Type C. Gross-total resection rates increased throughout the study period and correlated significantly with surgical experience. A worsened neurological state after surgery was seen in 61% of patients. This deterioration was transient in 41.5% and was a common observation after GTR. Permanent morbidity (19.5%) was lowest after GTR and correlated significantly with surgical experience and the preoperative neurological state. Further analysis showed that patients with tumors of thoracic levels, tumor hemorrhages, and malignant and recurrent tumors were at a higher risk for permanent morbidity. In the long term, tumor recurrence rates for ependymomas and benign astrocytomas correlated significantly with the amount of resection. Long-term morbidity affected 3.7% with a postoperative myelopathy related to cord tethering at the level of surgery and 21.9% in form of neuropathic pain syndromes. The rate of postsurgical cord tethering could be lowered significantly by using pia sutures after tumor resection. Neuropathic pain syndromes were more common after surgery for tumors with associated syringomyelia or those located in the cervical cord. CONCLUSIONS: Intramedullary tumors should be surgically treated as soon as neurological symptoms appear. Gross-total resection is possible for the majority of benign pathologies. Cervical tumors are associated with higher GTR and lower permanent morbidity rates compared with thoracic tumors. Surgery on intramedullary tumors should be performed by neurosurgeons who deal with these lesions on a regular basis as considerable experience is required to achieve high GTR rates and to limit rates of permanent morbidity.

Hemangiopericytomas in the spine: clinical features, classification, treatment, and long-term follow-up in 26 patients.

BACKGROUND: Intraspinal hemangiopericytoma (HPC) is a rare and malignant extra-axial tumor with a strong tendency to recur and metastasize. There is a paucity in the literature of large case series of patients with intraspinal HPCs. OBJECTIVE: We retrospectively analyzed the clinical radiological and histological features, classification, and treatment of 26 patients with HPCs in the spine. METHODS: Twenty-six patients with HPCs in the spine were treated at our institution between 1987 and 2010. Medical records were reviewed retrospectively to collect data on the clinical features, tumor morphology, surgical resection, recurrence, and follow-up. RESULTS: The 26 patients were predominantly male, and the mean age at diagnosis was 33.8 years. The intraspinal HPCs were divided into 3 types and 5 subtypes. Most of them involved the neighboring segments and/or caused bony erosion. All tumors were immunohistochemically positive for vimentin and negative for epithelial membrane antigen. All patients underwent at least 1 surgery, and most of them received postsurgical radiotherapy. The 5-year Kaplan-Meier rate of survival was 76%. The 5-year recurrence-free rate of survival was 29.4%. Only the tumor pathological grade was significantly associated with survival time and recurrence. CONCLUSION: High-grade tumors had a shorter survival time and recurred earlier than low-grade tumors. Surgical removal and postoperative radiotherapy are critical for the treatment of intraspinal HPCs. However, total resection may not necessary for these tumors. Stereotactic radiosurgery may be a good alternative to control the recurrent lesions.

Epidemiology of pediatric primary tumors of the nervous system: a retrospective study of 633 cases from a single Moroccan institution.

BACKGROUND AND PURPOSE: There are several reports regarding the epidemiology of pediatric brain tumors. However, little is known about the profile of pediatric brain tumors in Africa especially in Morocco in particular. The authors report the results of epidemiological analysis of a retrospective review of childhood primary brain tumors in a single institution. METHODS: A retrospective review of all cases of primary brain from 1 month to 15 years diagnosed at the Department of Pathology of the Hospital of Specialities of Rabat between January 1991 and December 2009 was performed. RESULTS: Six hundred and thirty-three primary tumors of the central nervous system were reviewed with a mean of 33.31 cases per year. According to the gender, 55% of the tumors occurred in males and 45% in females. The mean age was 8.36 years. Of all the tumors, 47% were situated in the supratentorial compartment, 48% in the infratentorial compartment, and 5% in spinal cord. In the infratentorial compartment, 82% of tumors are located in the cerebellum, 15% in the fourth ventricle, 2% in the brain stem and 1% in the cerebellar pontine angle. In the supratentorial compartment, two third of the tumors were located in the cerebral hemispheres and the sellar region. Thus 39% of tumors are located in the cerebral hemispheres followed by the sellar/suprasellar region (30%), lateral and third ventricles (11%), pineal region (8%), meninges (5%), choroid plexus (4%), and optic chiasma/tracts (3%). The most common types of tumors diagnosed were pilocytic astrocytoma and medulloblastoma together accounting for nearly half of the cases (46%) (23.1% and 22.9% respectively), followed by craniopharyngiomas (9%), ependymomas grade II (6.5%), glioblastomas (6%), astrocytomas grade II (4.4%), ependymomas grade III (3.9%). The other tumors represent 22.6%. CONCLUSION: We think that our results reflect fairly well the incidence of tumors of the nervous system in children due to the fact that this study was performed through many years in a single institution with a homogeneous neuropathological approach.

Natural history of intradural-extramedullary spinal cord tumors.

The objective of the present study was to investigate the natural history of intradural-extramedullary spinal cord tumors. Nine cases of intradural-extramedullary tumors were observed over the 2 years. The physical and magnetic resonance imaging (MRI) examination were performed in the first examination and every other year. Tumors were classified as the schwannoma type and the meningioma type based on the MRI findings. The tumor volume was calculated by the craniocaudal length on a sagittal image and maximum transverse diameter on an axial image of MRI, every year. The annual growth rate, which was defined as the change in the volume each year compared to the volume of the previous year, was examined. There were six cases in the schwannoma type and three cases in the meningioma type. The schwannoma type tumors presented several growth patterns: unchanging, continuous slight growth, and initial slight growth followed by rapid growth during the observation period (6.7 ± 2.7 years), while the meningioma type tumors presented the continuous growth pattern during the observation period (4.3 ± 2.5 years). The average annual growth rate was 2.3 ± 5.5% in the schwannoma type and 7.0 ± 8.5% in the meningioma type. Schwannoma type tumors showed relatively less change in their size and would be observed for a longer time.

Comparative analysis on the diagnosis and treatments of multisegment intramedullary spinal cord tumors between the different age groups.

Multisegment intramedullary spinal cord tumors (MSICT) are a special type of spinal cord tumor. Up to now, no comparative clinical study of MSICT has been performed according to different age groups. Seventy-seven patients underwent microsurgery for MSICT. As grouped with two different methods, the parametric and nonparametric data of MSICT and patients were comparatively analyzed using statistically correlative methods. Forty-eight patients were males and 29 were females, ranging in age from 4 to 64 years (mean, 32.9 years). Among the six groups, being divided with intervals of 10 years, the whole difference in the initial symptoms of patients (Z = 17.4, P = 0.004) and in the histological classification of tumors (Z = 12.5, P = 0.03) was statistically significant, respectively. Neurodevelopmental tumor and benign glioma predominated in adolescents and decreased in frequency into adulthood where ependymoma became more predominant. In the 25 years old grouping method, there were 27 adolescent and 50 adult patients. The difference in initial symptoms of patients (Z = -2.08, P = 0.04) was statistically significant between the two groups. Pain with motor weakness and gait deterioration predominated in adolescents and decreased in frequency into adulthood where sensory disturbances became more predominant.