Treatment options and prognosis for multicentric juvenile pilocytic astrocytoma

Intramedullary spinal cord tumors in pediatric patients presenting later with brain lesions: case series and systematic review of the literature

PURPOSE

Intramedullary spinal cord tumors are an uncommon pathology in adults and children. Most descriptive studies of intramedullary spinal cord tumors have not focused on a possible association with future brain lesions. To the best of our knowledge, few reports describe this potential relationship. This is one of the most extensive case series of secondary brain lesions of intramedullary spinal cord tumors in the pediatric population.

METHODS

Retrospective chart review was performed on pediatric patients (21 years old and younger) who underwent resection of an intramedullary spinal cord tumor at two tertiary care hospitals from 2001 to 2020. Patients previously treated or diagnosed with spinal cord tumor, and subsequent development of intracranial manifestation of the same or different tumor, were included. Data regarding epidemiology, surgical intervention, and clinical and follow-up course were gathered. Data analysis was performed according to a standardized clinical protocol with a literature review.

RESULT

More than 500 patients underwent intradural spinal tumor resection surgeries at participating hospitals from 2001 to 2020. After excluding adult patients (older than 21 years old) and those with extramedullary lesions, 103 pediatric patients were identified who underwent resection of an intramedullary spinal cord tumor. Four underwent resection of an intermedullary tumor and later in their follow-up course developed a secondary intracranial neoplasm. In every case, the secondary neoplasm had the same pathology as the intramedullary tumor. Three of the patients had tumors at the cervico-thoracic junction, and one patient had a high cervical tumor. These patients had a negative primary workup for any metastatic disease at the time of the presentation or diagnosis. Complete and near complete resection was performed in three patients and subtotal in one patient.

CONCLUSION

Secondary brain tumors disseminated after initial spinal cord tumor are extremely rare. This study aims to allow specialists to better understand these pathologies and treat these rare tumors with more certainty and better expectations of unusual associated lesions and conditions.

Unraveling the signaling mechanism behind astrocytoma and possible therapeutics strategies: A comprehensive review

BACKGROUND

A form of cancer called astrocytoma can develop in the brain or spinal cord and sometimes causes death. A detailed overview of the precise signaling cascade underlying astrocytoma formation has not yet been revealed, although various factors have been investigated. Therefore, our objective was to unravel and summarize our current understanding of molecular genetics and associated signaling pathways with some possible therapeutic strategies for astrocytoma.

RECENT FINDINGS

In general, four different forms of astrocytoma have been identified in individuals, including circumscribed, diffuse, anaplastic, and multiforme glioblastoma, according to a recent literature review. All types of astrocytoma have a direct connection with some oncogenic signaling cascade. Common signaling is MAPK cascade, including Ras-Raf-ERK, up-regulated with activating EGFR/AKT/PTEN/mTOR and PDGFR. Recent breakthrough studies found that BRAF mutations, including KIAA1549: BRAF and BRAF V600E are responsible for astrocytoma progression. Additionally, cancer progression is influenced by mutations in some tumor suppressor genes, such as the Tp53/ATRX and MGMT mutant. As synthetic medications must cross the blood-brain barrier (BBB), modulating signal systems such as miRNA is the primary option for treating patients with astrocytoma. However, available surgery, radiation therapy, and experimental therapies such as adjuvant therapy, anti-angiogenic therapy, and EGFR-targeting antibody drug are the usual treatment for most types of astrocytoma. Similar to conventional anticancer medications, some phytochemicals slow tumor growth by simultaneously controlling several cellular proteins, including those involved in cell cycle regulation, apoptosis, metastatic spread, tyrosine kinase, growth factor receptor, and antioxidant-related proteins.

CONCLUSION

In conclusion, cellular and molecular signaling is directly associated with the development of astrocytoma, and a combination of conventional and alternative therapies can improve the malignancy of cancer patients.

Update for astrocytomas: medical and surgical management considerations

Astrocytomas include a wide range of tumors with unique mutations and varying grades of malignancy. These tumors all originate from the astrocyte, a star-shaped glial cell that plays a major role in supporting functions of the central nervous system (CNS), including blood-brain barrier (BBB) development and maintenance, water and ion regulation, influencing neuronal synaptogenesis, and stimulating the immunological response. In terms of epidemiology, glioblastoma (GB), the most common and malignant astrocytoma, generally occur with higher rates in Australia, Western Europe, and Canada, with the lowest rates in Southeast Asia. Additionally, significantly higher rates of GB are observed in males and non-Hispanic whites. It has been suggested that higher levels of testosterone observed in biological males may account for the increased rates of GB. Hereditary syndromes such as Cowden, Lynch, Turcot, Li-Fraumeni, and neurofibromatosis type 1 have been linked to increased rates of astrocytoma development. While there are a number of specific gene mutations that may influence malignancy or be targeted in astrocytoma treatment, O 6-methylguanine-DNA methyltransferase (MGMT) gene function is an important predictor of astrocytoma response to chemotherapeutic agent temozolomide (TMZ). TMZ for primary and bevacizumab in the setting of recurrent tumor formation are two of the main chemotherapeutic agents currently approved in the treatment of astrocytomas. While stereotactic radiosurgery (SRS) has debatable implications for increased survival in comparison to whole-brain radiotherapy (WBRT), SRS demonstrates increased precision with reduced radiation toxicity. When considering surgical resection of astrocytoma, the extent of resection (EoR) is taken into consideration. Subtotal resection (STR) spares the margins of the T1 enhanced magnetic resonance imaging (MRI) region, gross total resection (GTR) includes the margins, and supramaximal resection (SMR) extends beyond the margin of the T1 and into the T2 region. Surgical resection, radiation, and chemotherapy are integral components of astrocytoma treatment.

Pilocytic Astrocytoma of the Cerebellopontine Angle with cerebrospinal fluid Spread in an Adult: A Case Report

Introduction Pilocytic astrocytoma of the cerebellopontine angle (CPA) is uncommon, and its spread to the cerebrospinal fluid (CSF) at the time of diagnosis has not been reported in the literature.

Case Presentation We report the case of a 33-year-old man with multifocal pilocytic astrocytoma diagnosed by magnetic resonance imaging (MRI) and confirmed by histopathological examination, and present the radiological and histopathological findings.

Conclusion In the case herein reported, we observed spread of the pilocytic astrocytoma of the CPA to the CSF at the initial diagnosis, and early detection by MRI is very important regarding the treatment modality and prognosis.

The evolving landscape of pilocytic astrocytoma: a bibliometric analysis of the top-100 most cited publications

BACKGROUND

Pilocytic astrocytomas are the most common low-grade glioma of the central nervous system that typically occurs in children, and much research has been dedicated to characterizing their molecular features and clinical courses. We provide an overview of the current literature through the use of a bibliometric analysis of the top 100 most cited publications discussing pilocytic astrocytomas.

METHODS

We identified the top 100 most cited publications discussing pilocytic astrocytomas. Articles were ranked based on the number of citations. Descriptive statistics and univariate analysis were used to determine any trends or significant differences in the data.

RESULTS

Of the top 100 articles, 50 were basic science (50%), 34 were clinical (34%), and 16 were review (16%). The number of citations ranged from 79 to 921, with 123 being the median. The US had the most first authors and principal authors (n = 53 and n = 54, respectively). Years of publication had a left-skewed distribution and peaked during 2011 with 12 articles published in that year. Sixty percent of basic science articles investigated BRAF/MAPK pathways, while 67.6% of clinical articles focused on evaluating treatment options for pilocytic astrocytomas. Compared to basic science and clinical articles, review articles were published more recently (p < 0.001), had fewer authors (p = 0.025) and were published in journals with higher impact factors (p = 0.022).

CONCLUSION

Research regarding pilocytic astrocytomas has increased over the past three decades. Future directions of research point towards employing targeted therapies and discovering additional cellular pathways contributing to disease pathogenesis.

Multicentric Glioma: An Ideal Model to Reveal the Mechanism of Glioma

As a special type of glioma, multicentric glioma provides an ideal pathological model for glioma research. According to the stem-cell-origin theory, multiple lesions of multicentric glioma share the same neuro-oncological origin, both in gene level and in cell level. Although the number of studies focusing on genetic evolution in gliomas with the model of multicentric gliomas were limited, some mutations, including IDH1 mutations, TERTp mutations and PTEN deletions, are found to be at an early stage in the process of genetic aberrance during glioma evolution based on the results of these studies. This article reviews the clinical reports and genetic studies of multicentric glioma, and intends to explain the various clinical phenomena of multicentric glioma from the perspective of genetic aberrance accumulation and tumor cell evolution. The malignant degree of a glioma is determined by both the tumorigenicity of early mutant genes, and the stemness of early suffered cells.

Primary adult unilateral thalamic pilocytic astrocytoma with von Recklinghausen's disease mimicking lymphoma: A case report

Thalamic astrocytomas are rare central nervous system tumors that account for 1%-1.5% of all brain tumors. Their Clinical features depend on anatomical involvement. For these tumors, gross total resection is so difficult due to their deep location and also the infiltration of the optic pathway or brain stem. Unilateral adult thalamic locations are rarely described in the literature. Their radiological features often suggest lymphoma. The authors report here a new case of a primary unilateral thalamic pilocytic astrocytoma mimicking lymphoma diagnosed after a stereotactic core biopsy in a 62-year-old male patient with von Recklinghausen's disease and which is responsible for Dejerine–Roussy syndrome. The authors will proceed with a comprehensive review of literature regarding this rare entity.

Brain low-grade gliomas with high-grade spinal localization. Report of a clinical case and systematic literature review

INTRODUCTION

Oncological aggressiveness and the ability to present distant localizations are known in high-grade gliomas (HGGs), but the knowledge about the possible aggressiveness of LGGs is scarce, especially concerning possible spinal localization.

EVIDENCE ACQUISITION

A systematic search of LGGs with spinal localization on the three primary online databases (PubMed/MEDLINE, Embase, and Cochrane) was conducted. We included adult patients with histological diagnosis of intracranial LGG and specified WHO grade showing a remote spinal localization during follow-up. Additionally, we present a case of a left temporal LGG presenting a spinal localization fourteen years after the first appearance. We compared the survival rates of LGGs in our series with those of LGGs without spinal localizations.

EVIDENCE SYNTHESIS

Seven articles dealing with the subject and eight patients were considered (including our case), with a mean age at diagnosis of 42.25 years (range 26-69 years). The mean latency between a diagnosis of intracranial LGGs and a spinal localization occurrence was 7.37 years (range 2-14 years), and an increased WHO grade of the spinal localization compared to the brain LGG was observed in all patients. There was no sign of intracranial progression at the time of spinal glioma diagnosis in four cases, including ours. Survival at ten years was 28% against a 10-year survival rate of 65-71% for LGGs without distant localization, as reported in the literature.

CONCLUSIONS

Spinal metastasis of intracranial LGGs is an adverse prognostic factor. Surgical violation of ventricles can play a role in the pathophysiology of CSF spread of tumor cells in LGGs.

Recurrent adult pilocytic astrocytoma presenting with intraventricular and leptomeningeal spread

Background

Infratentorial pilocytic astrocytomas are uncommon tumors in adulthood but are thought to be prognostically similar to their pediatric counterparts with excellent overall survival following gross total resection. However, given the relative rarity of these tumors, no management guidelines exist for recurrent adult pilocytic astrocytomas (APAs). This lack of consensus is especially problematic for inoperable recurrences or those with aggressive features concerning for malignant transformation.

Case Description

In 2017, a 26-year-old female presented with headaches, nausea, vomiting, and blurry vision. A brain magnetic resonance imaging (MRI) demonstrated a large, well-circumscribed mass within the fourth ventricle causing obstructive hydrocephalus. She underwent near-total resection through a midline suboccipital transtonsillar approach. Pathology demonstrated a World Health Organization Grade 1 pilocytic astrocytoma. Despite initial improvement in her symptoms, she developed worsening headaches and lethargy 10 months after surgery and repeat MRI demonstrated recurrent tumor within the entire ventricular system and the subarachnoid spaces of the left cerebellopontine angle suggesting leptomeningeal spread. Due to the unresectable nature of the recurrence, the patient declined any further intervention and succumbed to her disease 6 months later.

Conclusion

We present the first case of a recurrent APA presenting with intraventricular and leptomeningeal spread. Although thought to be a benign neoplasm, close interval follow-up with serial imaging is of essential, especially in those patients with known residual tumor, to prevent aggressive recurrences such as this.

A Case of Cisternal Pilocytic Astrocytoma Diagnosed with the Balanced Steady-State Free Precession Sequence for Magnetic Resonance Imaging: A Rare Cause of Subarachnoid Hemorrhage

Objectives

In approximately 15% of cases of spontaneous subarachnoid hemorrhage (SAH), an obvious source of bleeding cannot be identified by angiography; these are considered cases of SAH of unknown etiology. A rare case of cisternal pilocytic astrocytoma (PA) presenting with SAH is reported. The usefulness of the balanced steady-state free precession (bSSFP) sequence for magnetic resonance imaging (MRI) to detect small cisternal lesions is discussed.

Case Description

The case of a 73-year-old woman who developed repeated SAHs owing to a cisternal PA is presented. She experienced sudden onset of headache and vomiting, and brain computed tomography showed diffuse SAH, whereas angiography demonstrated normal vasculature. Follow-up imaging, including T1-weighted, T2-weighted, T1-weighted contrast-enhanced, and diffusion-weighted MRI, did not show any parenchymal or cisternal lesions, although computed tomography and fluid-attenuated inversion recovery MRI showed SAH in the same region. In contrast, the bSSFP sequence, taken as a different sequence on the same day, showed mixed-intensity reticular lesions in the left basal cistern, while neither hematoma nor positive findings were identified with the other sequences. Based on the radiologic finding and the repeated history of SAH, the lesions were partially removed 2 weeks after onset. Histological examination showed a PA.

Conclusions

Despite being extremely rare, a small cisternal lesion should be considered as a cause of SAH of unknown etiology. The bSSFP sequence may be useful for detecting cisternal lesions that may be missed on the routine MRI sequences.

An elderly patient presenting with a primary spinal multifocal intradural extramedullary pilocytic astrocytoma: a case report and review of the literature

BACKGROUND

Pilocytic astrocytoma is a low-grade central nervous system tumor most commonly seen in children. Dissemination from a primary intracranial tumor along the neuroaxis has been described at both presentation and disease progression. However, the development of an intradural extramedullary pilocytic astrocytoma independent of a primary intraparenchymal tumor in an adult patient with no history of pilocytic astrocytoma has rarely been reported.

CASE PRESENTATION

A 69-year-old woman presented with progressive myelopathic symptoms and thoracic radicular pain. MRI imaging of the whole spine showed an enhancing intradural extramedullary lesion extending from the cervical cord to T11 causing cord compression. Laminectomies were performed for surgical decompression and histopathology was consistent with pilocytic astrocytoma. Complete staging was done that included imaging of the brain and cerebrospinal fluid cytology. No other tumor was found by these methods. Postoperatively the patient was treated with large field spinal radiation and concurrent chemotherapy followed by adjuvant chemotherapy. She has thus far been clinically and radiographically stable.

CONCLUSION

This is a rare case of an adult with multiple spinal pilocytic astrocytomas in an intradural extramedullary location, typically the result of cerebrospinal fluid dissemination of neoplastic cells from a primary intracranial tumor site (i.e. drop metastasis). No conventional primary tumor was identified in this patient, suggesting these tumors may arise from heterotopic gliomas.

Long-term outcomes of primarily metastatic juvenile pilocytic astrocytoma in children

OBJECTIVE Primarily metastatic juvenile pilocytic astrocytoma (JPA) is rare, likely representing 2%-3% of all cases of JPA. Due to the rarity of primarily metastatic JPA, there is currently no standard treatment paradigm and the long-term outcomes are not fully known. The goal of this case series was to add to the current understanding of this disease process. METHODS The authors searched a comprehensive database of pediatric patients with brain and spinal cord tumors treated at Lucile Packard Children's Hospital from 1997 to 2016 and identified 5 patients with primarily metastatic JPA. A retrospective chart review was performed and details of the patients' treatment and clinical course were recorded for further analysis. RESULTS For the 5 patients with primarily metastatic JPA, the mean follow-up period was 12.3 years. All patients in our series had biopsies or subtotal resections and upfront treatment. Three patients were treated with chemotherapy alone, one was treated with chemotherapy and radiotherapy, and one was treated with radiotherapy alone. Four patients had stable disease after initial treatment, and one patient had multiple episodes of progressive disease but underwent successful salvage therapy and has had stable disease for 19 years. One patient died of an intracerebral hemorrhage 10 years following initial radiation treatment believed to be secondary to radiation vasculopathy. CONCLUSIONS Evaluation of the entire neuraxis should be performed in all instances of initial JPA diagnosis to properly assess for primarily metastatic disease. Many patients with primarily metastatic JPA will have stable disease after upfront treatment, although the higher rate of stable disease found in this series relative to other reports is likely secondary to the small sample size.

A Case of Leptomeningeal Dissemination of Pilocytic Astrocytoma in a Child

We present the case of a 2-year-old boy with progressive left-sided weakness and a cranial magnetic resonance imaging (MRI) scan showing a lesion with a cystic component in the right thalamus and basal ganglia. The lesion was subtotally resected and diagnosed as a pilocytic astrocytoma by histopathology. Tumor seeding along the surgical tract was seen on MRI 16 days and 10 weeks after surgery. The patient received vincristine and carboplatin, and MRI performed 4 months after chemotherapy revealed no additional or residual lesions. This case illustrated that a World Health Organization grade I astrocytoma could disseminate along the surgical tract.

Suprasellar pilocytic astrocytoma in an adult with hemorrhage and leptomeningeal dissemination: case report and review of literature

Pilocytic astrocytoma (PA) is a low-grade tumor. It has an excellent prognosis after total resection. Leptomeningeal dissemination and hemorrhage are very rare to be associated with PA and lead to unfavorable prognosis. A 35-year-old man was diagnosed with a hemorrhagic suprasellar PA in 2006. Subsequent examination in 2007 revealed another large subdural hemorrhagic lesion in the sacral region, which proved to be PA by histopathologic assessment. Other leptomeningeal foci were discovered mainly at the craniocervical junction. The patient underwent subtotal resection and received chemotherapy with disease control for 7 years. Progression of the disseminated disease has recently occurred; however, the patient is still alive with stable disease after radiotherapy. The radiological features, management, and relevant literature are also presented. Our report heightens the awareness of PA in the adult population and the importance of close surveillance for the leptomeningeal spread, especially for sellar region tumors.

Cranial Pilocytic Astrocytoma With Spinal Drop Metastasis in an Adult: Case Report and Literature Review

BACKGROUND

Pilocytic astrocytoma (PA) is a benign neoplasm that typically occurs in the brain within the pediatric and adolescent age groups and is uncommon in adults. It rarely occurs within the ventricles, and the overall prognosis is favorable. A PA of the brain with spinal metastasis at presentation has never been reported in an adult.

CASE DESCRIPTION

We report a case of a 47-year-old man presenting with sudden-onset frontal headache associated with nausea and lethargy in addition to a background of a longer history of back pain and headache. Radiologic imaging revealed an acute intraparenchymal hemorrhage in the right parieto-occipital lobes with intraventricular extension within a peripherally enhancing heterogeneous lesion. Magnetic resonance imaging of the spine revealed a sacral intradural tumor. The patient underwent surgical resection of the intracranial mass followed by debulking of the spinal lesion. Histopathologic study revealed that both the cranial and spinal tumors were PA.

CONCLUSIONS

This case illustrates a unique instance of hemorrhage into a cerebral PA with a spinal metastasis. To our knowledge, this is the first such case reported in an adult. We review the literature on the subject.

Hemangioblastomas with leptomeningeal dissemination: case series and review of the literature

BACKGROUND

Leptomeningeal dissemination of hemangioblastomas (HB) of the central nervous system (CNS) is extremely rare. Few studies have reported leptomeningeal involvement in sporadic HB or in HB associated with von Hippel-Lindau syndrome. The clinical and radiological features of leptomeningeal involvement in HB after surgery have not been described in detail.

MATERIALS AND METHODS

This retrospective case review involved patients from three different tertiary referral centers with leptomeningeal dissemination of HB after surgery for the primary mass. A literature review was also performed to describe the clinical and radiological characteristics and long-term outcomes of patients who developed leptomeningeal dissemination after initial surgical resection.

RESULTS

This study included seven patients, five males and two females, ranging in age from 36 to 54 years. Incidence of leptomeningeal dissemination in patients with HB was about 4.3 % (3/69). It appeared at a mean 94.9 months (range, 39-204 months) after gross total resection of CNS HBs. Three of the seven patients died 5, 38, and 79 months, respectively, after diagnosis of leptomeningeal dissemination. Review of the literature identified 21 patients with characteristics of leptomeningeal dissemination similar to those in our series.

CONCLUSIONS

Leptomeningeal dissemination of HB is a rare pattern of long-term recurrence. Long-term outcomes may be fatal. The long developmental period suggests that early detection and aggressive management may improve prognosis in patients with CNS leptomeningeal dissemination of HB.

Metastatic Low-Grade Gliomas in Children: 20 Years' Experience at St. Jude Children's Research Hospital

BACKGROUND

Patients with low-grade gliomas (LGG), which are the most common childhood brain tumors, have excellent long-term survival. Dissemination of LGG is rare. Robust data on the incidence, presentation, patterns of dissemination, disease behavior, outcome, and best-management approaches do not exist. We describe 20 years of follow-up of children with metastatic LGG.

PROCEDURE

Data collected during the period 1990-2010 were retrospectively reviewed for the following inclusion criteria: diagnosis of metastatic LGG, age younger than 21 years at initial diagnosis, and magnetic resonance imaging of the brain and/or spine at diagnosis and/or follow-up. Patient demographics, pathology, treatment modalities, and outcome were reviewed.

RESULTS

Of 599 patients with LGG, 38 (6%) had metastatic disease at either diagnosis or follow-up. Most tumors (87%) were located in the brain, and half of the patients had metastatic disease at presentation. The most common diagnosis was pilocytic astrocytoma (55%). Chemotherapy was the most common initial treatment modality. Median survival of the group was 6.2 years (range, 0.1-16.9 years). Fifteen (40%) patients died at a median of 6 years from diagnosis (range, 0.8-15 years). Overall survival at 5, 10, and 15 years was 80.7 ± 6.6%, 63.0 ± 10.2%, and 50.9 ± 16.0%, respectively.

CONCLUSION

This study describes the longest follow-up of children with metastatic LGG. LGG is underestimated and entails major morbidity and mortality. Prospective studies are needed to learn the true incidence, study the biology, and determine the best approaches to diagnosis, treatment, and follow-up.

[Low-grade gliomas: review of 10 years]

INTRODUCTION

Central nervous system (CNS) tumors are the most common solid tumors in children. Among these, the low-grade gliomas are the most common type, accounting for up to 30-50% of them.

PATIENTS AND METHODS

A retrospective analysis was carried out on the epidemiology, clinical characteristics, tumor location, histology, treatment, outcome and long-term sequelae of 111 patients diagnosed with low-grade glioma in the Niño Jesús Children's Hospital of Madrid from January 2002 to December 2011.

RESULTS

Of the 111 patients, there were 57 boys and 54 girls. The mean age was 7.26 years (range, 2 months - 19 years). The most common symptoms of presentation were headache (27%) and vomiting (19%). The most common locations were the cerebral hemispheres (38%), followed by the brainstem (27.4%), and cerebellum (18.5%). Histological examination was performed in 89 patients (80.18%). Pilocytic astrocytoma was the most common histological type. Diagnostic biopsy was performed in 20 patients (22.5%), partial resection in 38 patients (42.7%), and total resection in 31 patients (34.8%). Sixteen patients received chemotherapy (14%), and eighteen patients received radiotherapy (16%). Overall survival was 88.3%. Long term hearing, visual and endocrine sequelae were note in 1, 5, and 4 patients, respectively.

CONCLUSIONS

The most common histological type is pilocytic astrocytoma. Overall survival was 88.3%. Only 9% of patients had some kind or auditory, visual or endocrine sequelae.

Pilocytic astrocytoma with leptomeningeal dissemination

PURPOSE

Pilocytic astrocytoma (PA) is a common pediatric glioma that is generally characterized by indolent growth. However, there are reports of PA disseminating throughout the central nervous system. Given the rarity of dissemination, the appropriate treatment for these patients is poorly defined. In this case series, we describe the clinical characteristics and treatment outcomes of six children treated for disseminated PA at our institution and review the current published literature.

METHODS

Six cases of disseminated PA treated at the University of Texas MD Anderson Cancer Center were identified. Demographics, disease characteristics, and follow-up data were compiled. Fifty-three reported cases were identified in the published literature.

RESULTS

Our cohort's mean age at presentation was 7 years, and the mean time to identification of disseminated disease was 12 months after initial diagnosis. Two patients underwent chemotherapy, and all underwent proton beam radiation therapy to all or part of the craniospinal axis. With a median follow-up of 24 months after radiation therapy, five of six patients were alive, four with stable disease and one with progressive disease.

CONCLUSIONS

Treatment of disseminated PA is frequently multi-modal, including surgical resection, chemotherapy, and radiation therapy. On the basis of early clinical data, extended-field radiation therapy is a viable option for treating disseminated PA.

Metachronous, multicentric glioma of pilocytic astrocytoma with oligodendroglioma-like component and oligodendroglioma through distinct genetic aberrations

This patient presented with a rare case of metachronous, multicentric gliomas first manifesting as headache and nausea in 1983 when he was an 8-year-old boy. Computed tomography revealed a cerebellar tumor and the tumor was subtotally resected. The histological diagnosis was pilocytic astrocytoma, and radiation therapy to the posterior fossa and chemotherapy consisting of nimustine hydrochloride and fluorouracil were performed. In 1989, at age 14 years, the patient presented with local recurrence. He underwent gross-total resection of the tumor, and histological examination revealed that the tumor consisted of classic pilocytic astrocytoma with a biphasic pattern and a small oligodendroglioma-like component. In 2011, at age 36 years, he presented with seizure. Magnetic resonance imaging revealed a mass lesion in the right middle frontal gyrus. Gross-total resection of the tumor was performed, and the histological diagnosis was oligodendroglioma. Genetic analyses revealed amplification of the BRAF gene in both the primary cerebellar pilocytic astrocytoma and the recurrent tumor with biphasic features, as well as a BRAF V600E missense mutation in the oligodendroglioma-like component. On the other hand, the IDH1 R132H mutation, instead of aberrations of the BRAF gene, was identified in the oligodendroglioma arising in the right frontal lobe. Different types of aberrations of the BRAF gene in the classic and oligodendroglioma-like component in the recurrent pilocytic astrocytoma suggest that they had different cell origins or that amplification of BRAF was negatively selected under the de novo BRAF V600E mutation. In addition, the aberration profiles of IDH1 and BRAF suggest that the oligodendroglioma arose independent of cerebellar pilocytic astrocytoma.

Multicompartmental cerebrospinal fluid dissemination of cerebellar pilocytic astrocytoma at presentation

A 26-year-old male presented with a rare cerebellar pilocytic astrocytoma with multicompartmental subarachnoid metastases. Cerebrospinal fluid dissemination of low grade astrocytoma at presentation is rare in adults. In the present patient, clinical and neuroradiological follow-up at 4 years, without adjuvant treatment, revealed non progression of tumors. The occurrence of benign dormancy, low grade tumor histology and multifocal involvement of the neuraxis is rare. Close clinical observation is the best approach for management of such a patient. The relevant literature is discussed.

Impact of chemotherapy on disseminated low-grade glioma in children and adolescents: report from the HIT-LGG 1996 trial

BACKGROUND

We describe demographic data of disseminated childhood low-grade glioma (DLGG) prospectively recruited in the HIT-LGG 1996 study and evaluate the impact of primary chemotherapy (CT) on the outcome of these tumors, which have previously only been described in small and retrospective series.

PATIENTS AND METHODS

The multicenter study HIT-LGG 1996 accrued 1181 children and adolescents with low-grade glioma. 61 patients (5.2%) had tumor dissemination, with 2.8% being present at diagnosis. Frequencies of dissemination for different subgroups were calculated. Efficiency of first-line CT with vincristine/carboplatin was defined in 24 children with dissemination prior to first-line non-surgical-treatment.

RESULTS

Incidence of dissemination was high among infants (16%) with hypothalamic-chiasmatic-glioma (HCG) and diencephalic syndrome. A relevant percentage of HCG showed isolated spinal dissemination. CT achieved objective and overall response rates of 25% and 79% of the primary tumor and a similar response of disseminated lesions. Clinical stabilization or improvement could be achieved in the majority of patients during treatment. However, 20 of 24 patients experienced further progression and 5-year PFS was 6%. Dissemination prior to CT was a negative prognostic factor for PFS within the study (P = 0.005). Overall-survival of primary DLGG was inferior compared to LGG without dissemination at diagnosis (P < 0.001).

CONCLUSION

Complete MRI scan should be a standard diagnostic procedure in young children with hypothalamic-chiasmatic tumors especially if presenting with diencephalic syndrome. Dissemination in childhood LGG relates to impaired PFS. CT delays progression for responders. Multicenter studies have to evaluate the efficacy of extended treatment strategies in DLGG to improve outcome.

Pediatric cerebellar pilomyxoid-spectrum astrocytomas

OBJECT

Pediatric cerebellar astrocytomas with pilomyxoid features include classic pilomyxoid astrocytomas (PMAs) and intermediate pilomyxoid tumors (IPTs). Since the original description of PMA in 1999, most reports in the literature have described PMAs arising from the hypothalamic/chiasmatic region. To the authors' knowledge, PMAs arising from the posterior fossa have not been discussed in the neurosurgical literature. Intermediate pilomyxoid tumors, or tumors with pathological features of both pilocytic astrocytoma (PA) and PMA, have only recently been described. In this article, the authors present 2 cases that fall within the spectrum of pediatric cerebellar PMA-including a classic PMA and an intermediate pilomyxoid tumor. The authors compare the radiological presentation, surgical results, and postoperative course to findings in a cohort of 15 patients with cerebellar PAs.

METHODS

Between 2003 and 2010, 2 patients with pilomyxoid-spectrum astrocytomas underwent treatment at Vanderbilt Children's Hospital. One was a 22-month-old girl who presented with progressive gait disturbance and falls. The other was a 4-year-old girl who presented with ataxia and generalized weakness. In a retrospective review of pediatric cerebellar neoplasms resected by the senior author during this period, these tumors comprised 4% of cerebellar neoplasms and approximately 10% of cerebellar glial neoplasms.

RESULTS

Both patients were treated with midline suboccipital craniotomy for resection. In both cases, tumor invasion anteriorly into the brainstem prevented gross-total resection. the patient in Case 1 was placed on chemotherapy following pathological diagnosis and later developed definitive evidence of leptomeningeal dissemination (LD) 3 years after the operation. The patient in Case 2 was placed on chemotherapy after exhibiting progressive evidence of local recurrence (findings were negative for LD) 12 months following resection.

CONCLUSIONS

Pediatric patients with cerebellar pilomyxoid-spectrum astrocytomas appear to suffer higher rates of local recurrence and LD than pediatric patients with cerebellar PAs.

Diagnosis and management of multifocal gliomas

Patients who present with multiple cerebral tumors are usually considered as having metastatic disease. If they have a history of a primary cancer in another site, the brain tumors are considered metastases and are usually managed with standard whole-brain radiotherapy. If no primary cancer site is known, a diagnostic work-up is performed, but if no primary site is found, they are still considered as brain metastases from an unknown primary site. Thus, such patients can either have brain biopsy (recommended) for further diagnostic consideration or, occasionally, they can be treated with whole-brain radiotherapy, depending on the age, performance status and wish of the patient. However, in some of these patients the multiple brain tumors represent multifocal glioma rather than metastases, resulting in incorrect treatment. In such cases, various MRI characteristics may be helpful in directing towards the correct diagnosis. Thus, patients who present with multiple brain tumors should not always be considered to have metastatic disease even if they have a previous diagnosis of systemic cancer, and multifocal glioma should be ruled out.

Use of T2 signal intensity of cerebellar neoplasms in pediatric patients to guide preoperative staging of the neuraxis

OBJECT

The question of whether to obtain routine or selective preoperative imaging of the neuraxis in pediatric patients with cerebellar neoplasms remains a controversial topic. Staging of the neuraxis is generally considered beneficial in patients with neoplasms associated with an elevated risk of leptomeningeal dissemination (LD). When these studies are obtained preoperatively, there is a decrease in the number of false-positive images related to debris in the immediate postoperative period. Additionally, knowledge of the extent of spread has the potential to affect the risk/benefit analysis of aggressive resection. Although the majority of pediatric neurosurgeons surveyed choose to obtain selective preoperative imaging of the neuraxis in cases of cerebellar neoplasms "with findings suggestive of high-grade pathology," an evidence-based protocol in the literature is lacking. The goal of this study was to assess radiological characteristics of tumors with an elevated risk of LD and identify a method to help guide preoperative imaging of the neuraxis.

METHODS

The authors first reviewed the literature to gain an appreciation of the risk of LD of pediatric cerebellar neoplasms based on underlying histopathology and/or grade. Available evidence indicates preoperative imaging of the neuraxis in patients with Grade I tumors to be of questionable utility. In contrast, evidence suggested that preoperative imaging of the neuraxis in patients with Grades II-IV neoplasms was clinically warranted. The authors then evaluated an extensive base of neuroradiological literature to identify possible MR imaging and/or CT findings with the potential to differentiate Grade I from higher-grade neoplasms in pediatric patients. They analyzed the preoperative radiological findings in 50 pediatric patients who had undergone craniotomy for resection of cerebellar neoplasms at Vanderbilt Children's Hospital since 2003 with reference to 7 chosen radiological criteria. Logistic regression models were fit using radiological features to determine the best predictors of Grades II-IV tumors. Receiver operating characteristic methods were used to identify diagnostic properties of the best predictors.

RESULTS

The relative T2 signal intensity (RT2SI), an indirect measure of the water content of the solid component of the tumor, was best able to identify neoplasms with an elevated risk of LD. An RT2SI value of 0.71 was selected by the authors as the best operating point on the curve. Of the 31 neoplasms retrospectively designated as hypointense T2-weighted lesions (RT2SI ≤ 0.71), 30 (97%) were Grade II or higher. All medulloblastomas, ependymomas, and high-grade (Grades III and IV) neoplasms were hypointense T2-weighted lesions. Of the 19 T2-weighted hyperintense neoplasms (RT2SI > 0.71), 16 (84%) were Grade I and 3 were Grade II.

CONCLUSIONS

Measurement of the RT2SI can help predict Grade II-IV tumors at an elevated risk of leptomeningeal spread and guide staging of the neuraxis. Pediatric patients with cerebellar neoplasms found to have an RT2SI of less than or equal to 0.71 are recommended for neuraxis imaging prior to surgery.

Magnetic resonance imaging features of pilocytic astrocytoma of the brain mimicking high-grade gliomas

OBJECTIVE

The typical magnetic resonance/computed tomographic imaging appearance of pilocytic astrocytoma (PA) is that of a cyst with an intensely enhancing mural nodule. The purpose of this study was to illustrate the aggressive imaging features of PA.

METHODS

One hundred patients referred to the cancer center with brain tumors histologically proven to be PA were retrospectively reviewed (95 by magnetic resonance imaging and 5 by computed tomographic imaging) and analyzed.

RESULTS

The patient population includes 76 pediatric patients younger than 18 years and 24 adults ranging from 19 to 45 years old. Tumor locations consisted of the following: optic chiasm (22), lateral ventricle (3), thalamus (12), basal ganglia (1), cerebral hemisphere (10), corpus callosum (2), brain stem (26), fourth ventricle (1), and cerebellum (23). The imaging appearance of PA consisted of typical features in 71 cases and aggressive features in 29 cases.

CONCLUSIONS

It is important to recognize the aggressive imaging appearance of PA (grade 1 astrocytoma) because it can be mistaken for high-grade gliomas and may thus lead to inappropriate therapy. Despite the aggressive imaging appearance of PA, there is no histopathologic evidence of anaplasia.

In pursuit of prognostic factors in children with pilocytic astrocytomas

OBJECTIVE

This study described a 23-year experience in the treatment of children with pilocytic astrocytomas (piloA) with the aim of identifying putative clinical, histopathological, and/or immunohistochemical features that could be related to the outcome of these patients.

METHODS

Clinical data of 31 patients under 18 years of age with piloA were obtained from 1984 to 2006.

RESULTS

The mean age at the time of surgery was 7.8 +/- 4.2 years (1 to 17 years), and the mean follow-up was 5.7 +/- 5.4 years (1 to 20 years). The most common site of tumor formation was the cerebellum (17), followed by brainstem (4), optic chiasmatic hypothalamic region (4), cerebral hemisphere (3), cervical spinal cord (2), and optic nerve (1). Gross total resection (GTR) was achieved in 23 (74.1%), mainly in those with tumors located in the cerebellum and cerebral hemispheres (P = 0.02). The global mortality rate was 6.4%. Nine patients were reoperated. Rosenthal fibers, eosinophilic granular bodies, microvascular proliferation, and lymphocytic infiltration were observed in most cases. The mean Ki-67LI was 4.4 +/- 4.5%. In all cases, Gal-3 expression in tumor cells was observed with variable staining pattern.

CONCLUSIONS

Aside from GTR, no other clinical, histopathological, or immunohistochemical features were found to be related to the prognosis. We postulate that strict follow-up is recommended if piloA is associated with high mitotic activity/Ki67-LI, or if GTR cannot be achieved at surgery. Tumor recurrence or progression of the residual lesion should be strictly observed. In some aspects, childhood piloA remains an enigmatic tumor.

Subarachnoid dissemination of intraventricular tumors following simultaneous endoscopic biopsy and third ventriculostomy

OBJECT

Endoscopic biopsy with concomitant third ventriculostomy (ETV) is a well-established diagnostic and therapeutic maneuver in patients presenting with noncommunicating hydrocephalus resulting from a tumor of the pineal region or posterior third ventricle. Fenestration of the floor of the third ventricle theoretically provides a conduit for the subarachnoid dissemination of an intraventricular tumor. The aim of this study was to ascertain the rate of leptomeningeal dissemination following this surgical procedure.

METHODS

The authors conducted a review of all patients for whom an ETV and simultaneous endoscopic biopsy procedure or tumor resection had been performed at their institutions between 1995 and 2008. Patients were divided into high or low risk groups by leptomeningeal metastatic potential based on pathology. All available postoperative clinical and radiographic data, including MR imaging of the brain and spinal cord, as well as CSF sampling were evaluated when available. A review of the literature was then conducted to establish rates of distant leptomeningeal dissemination for comparative purposes.

RESULTS

Thirty-two patients satisfied the criteria for study inclusion. Pathology revealed that 22 had a high risk for leptomeningeal dissemination. New leptomeningeal disease (1 yolk sac tumor and 1 pineoblastoma) occurred in 2 patients. The median clinical and brain MR imaging follow-ups overall were 34 (range 2-103 months) and 38 months (range 1-94 months), respectively. Follow-up MR imaging of the spine was performed in 12 patients (median 7 months postoperation), and CSF was analyzed in 15 patients (median 1 month postoperation). A Kaplan-Meier survival analysis predicted a 2-year metastasis-free survival of 94.7% for high-risk patients. Baseline rates of dissemination when ETV was not performed were in general between 8 and 24% for various high-risk pathologies according to a literature review.

CONCLUSIONS

The rate of leptomeningeal metastasis of tumors in this biopsy and ETV study was not increased when compared with rates from large series in the literature.

Pediatric low-grade gliomas and the need for new options for therapy: Why and how?

Pediatric low-grade gliomas are the most common tumors of the central nervous system in children, accounting for almost 50% of all childhood brain tumors. They are a heterogeneous group of tumors with different histologic subtypes. Most treatment studies address low-grade gliomas as a single entity, depriving us of histology-specific treatment outcomes. This is mostly due to a lack of understanding of tumor biology at the molecular level. Pediatric low-grade gliomas are not benign, and most incompletely resected tumors will progress and negatively affect quality of life. The advancements made in understanding sporadic pilocytic astrocytoma and neurofibromatosis 1-associated pilocytic astrocytoma in particular have paved the way for potential targeted therapy and biological stratification. Such progress in pilocytic astrocytoma needs to be consolidated and expanded to other histologic varieties of pediatric low-grade gliomas.

A case of neurofibromatosis 1 presenting with optic pathway glioma with an early onset and an aggressive course

Optic pathway glioma associated with neurofibromatosis 1 has a classically indolent course. However, involvement of the optic radiations is relatively rare and is associated with a more aggressive course. A three-year-old girl presented with strabismus and loss of vision in the left eye with relative afferent pupillary defect and optic disc pallor. She had multiple café au lait spots. Visually evoked potential was suggestive of an optic nerve conduction defect and magnetic resonance imaging of the brain was suggestive of an optic pathway glioma involving the optic nerves, the optic chiasma and the optic tracts. The optic radiations and the dentate nuclei had hamartomas. Optic nerve biopsy confirmed pilocytic astrocytoma. Radical radiotherapy under general anesthesia was subsequently given. This case report aims to highlight the involvement of the optic radiations and the unusually aggressive clinical course in this case.

Spinal Cord Pilomyxoid Astrocytoma: An Unusual Tumor

We present the imaging findings of a case of spinal pilomyxoid astrocytoma in a 29-year-old woman with history of neck and back pain and weakness of bilateral upper extremities. A contrast-enhanced magnetic resonance (MR) imaging study revealed an extensive intradural extramedullary lesion occupying most of the thecal sac extending from mid cervical up to the lumbosacral region with extensive contrast enhancement. Spinal pilomyxoid astrocytoma is rare with only three reported cases in pediatric population in the literature. This report illustrates the MR findings of an unusual case of intradural extramedullary spinal pilomyxoid tumor in an adult patient.

Spinal cord pilocytic astrocytoma with leptomeningeal dissemination to the brain. Case report and review of the literature

Leptomeningeal dissemination of low-grade spinal cord gliomas is an uncommon event. The authors report a unique case of leptomeningeal dissemination of a spinal cord pilocytic astrocytoma (PCA) to the intracranial cerebral subarachnoid spaces in a child. A 2-year-old boy presented with a loss of balance and the inability to walk or stand. An intradural intramedullary spinal cord tumor was identified, and the lesion was subtotally resected and diagnosed by the pathology department to be a PCA. Subsequently, the patient had recurrences of the intradural intramedullary tumor at 6 months and 2 years after his original presentation. He underwent a repeated resection of the recurrent tumor and fenestration of an associated syrinx on both occasions. The pathological characteristics of the reresected tumor remained consistent with those of a PCA. Postoperative imaging after his last surgery revealed diffuse intracranial leptomeningeal dissemination into the cisternal space surrounding the midbrain, the suprasellar region, and the internal auditory canal, as well as nodular subarachnoid disease in the upper cervical region. The patient then underwent chemotherapy, and total spine magnetic resonance (MR) imaging 2 months later demonstrated stability in the size of the spinal cord tumor and a decrease in the associated syrinx. However, an MR image of the head demonstrated two new areas of supratentorial subarachnoid leptomeningeal spread of the primary spinal cord tumor at the 2-month follow-up examination. At the 6-month follow-up examination, MR imaging of the head and spine demonstrated stable metastatic disease. This case illustrates a unique instance of supratentorial leptomeningeal dissemination of an intramedullary spinal cord PCA in a child.

Dissemination patterns of pilocytic astrocytoma

Two patients with multifocal pilocytic astrocytoma diagnosed by magnetic resonance imaging (MRI) and confirmed by histopathological examination are reported. They presented distinct sites and mechanisms of metastasis: to distant ventricles through the cerebral spinal fluid (CSF) in patient 1 and to contralateral parenchyma, possibly through white matter tracts, in patient 2, a pathway not so far reported in pilocytic astrocytoma. Early detection of multifocal pilocytic astrocytoma by MRI may change treatment strategies and improve prognosis.

Low‐Grade Gliomas in Adults

Low-grade gliomas are a heterogeneous group of neoplasms usually encountered in younger patient populations. These tumors represent a unique challenge because most patients will survive a decade or more and may be at a higher risk for treatment-related complications. Clinical observations over the years have identified a subset of low-grade gliomas that tends to manifest more aggressive clinical behavior and require earlier, more aggressive intervention. Clinical and molecular parameters may allow better assessment of prognosis and application of risk-adjusted management strategies that may include resection, radiation, or chemotherapy. Improved methods of long-term cognitive and functional assessment are desperately needed in this patient population.

Les astrocytomes pilocytiques du diencéphale de l’enfant

BACKGROUND AND PURPOSE

Pilocytic astrocytoma (PA) is a WHO grade I tumor of the central nervous system mostly arising in children and young adults. Management of diencephalic PA is a difficult challenge. Surgical treatment has to cope with both the difficulties of deep location and eloquent area tumors.

MATERIALS AND METHODS

We retrospectively reviewed seven pediatric cases (female: 4, male: 3) of diencephalic PA. Opto-chiasmatic tumors were excluded from the series. Mean age at diagnosis was 108 months (9 years) (range: 4 month-18 years), median age was 111 months. Median follow-up for the series was 125 months. Tumor locations were as followed: right thalamus: 2, both thalami: 1, hypothalamus: 3, and right basal ganglia: 1. At the onset, the first symptom was mostly raised intracranial pressure. The delay in diagnosis ranged from 48 hours up to 6 years.

TREATMENT

a shunting procedure was performed in 3 patients, a direct surgical approach in 5 patients (gross total removal: 2; partial removal: 3) and one patient had only a biopsy. Three children were re-operated. Three patients were treated by radiationtherapy (RT) after surgery. Chemotherapy was delivered for 4 children.

RESULTS

The overall survival rate was 71.4 months (almost 6 years) (range: 3-184 months). Median survival rate was 42 months (3.5 years). Three children died, two by tumor progression and one death related to late side-effects of RT. Four patients have a good quality of life with GOS I (n = 3) or II (n = 1). We observed tumor regression in two patients at 1 and 17 years after the beginning of treatment. Correct diagnosis was only made for two cases at the initial pathological examination.

CONCLUSION

The course of diencephalic PA is still unpredictable. The tumor can be controlled by a partial surgical removal, and a residual tumor can sometimes decrease in size after surgery. Gross total removal of these tumors, although difficult, may be performed. With cranial navigation systems, the risk is low. Pathological diagnosis is sometimes difficult to assess.

From the archives of the AFIP: pilocytic astrocytoma: radiologic-pathologic correlation

Pilocytic astrocytoma is the most common pediatric central nervous system glial neoplasm and the most common pediatric cerebellar tumor. This tumor has a noteworthy benign biologic behavior that translates into an extremely high survival rate-94% at 10 years-that is by far the best of any glial tumor. Most patients present in the first 2 decades, and clinical symptoms and signs are usually of several months duration and directly related to the specific location of the tumor. The cerebellum, optic nerve and chiasm, and hypothalamic region are the most common locations, but the tumor can also be found in the cerebral hemisphere, ventricles, and spinal cord. Surgical resection is the treatment of choice for all tumors, except for those involving the optic pathway and hypothalamic region, which may be treated with radiation therapy and chemotherapy. Cross-sectional imaging often demonstrates a classic appearance: a cystic mass with an enhancing mural nodule. Less common appearances are quite nonspecific. Surrounding vasogenic edema is rarely present, and this feature provides a valuable clue to the correct diagnosis. Accurate interpretation of imaging studies plays an essential role in directing treatment of these tumors, particularly when they arise in the optic pathway of patients with neurofibromatosis type 1. Disseminated disease and recurrence are extremely rare.

Spinal seeding of a pilocytic astrocytoma following multiple subtotal resections

We report the case of a 4-year-old girl presenting with spinal and leptomeningeal dissemination following several subtotal resections of cerebellar pilocytic astrocytomas.

New variants of malignant glioneuronal tumors: a clinicopathological study of 40 cases

OBJECTIVE

To demonstrate that malignant glioneuronal tumors comprise a large spectrum of neoplasms, without mature ganglion-like cells, that may histologically resemble any malignant glioma (World Health Organization Grade III or IV) but have a distinct biological behavior.

METHODS

This series includes all tumors diagnosed as malignant glioneuronal tumors (MGNTs) in our routine practice during a 2-year period during which neurofilament protein (NFP) immunostaining was performed in any case of suspected malignant glioma with unusual clinical, radiographic, and/or histological features. Immunostaining using neuronal markers (NFP, NeuN, synaptophysin, and chromogranin) and glial fibrillary acidic protein was done on paraffin sections after antigen retrieval. The presence of NFP-positive tumor cells, including those in mitosis, was used as a hallmark diagnostic criterion of MGNT.

RESULTS

All tumors coexpressed glial fibrillary acidic protein and NFP. Other neuronal markers tested were inconstantly expressed. No recurrence was observed at the primary site in 36.4% of patients who underwent gross total resection. Twelve patients (33.3%) developed intra-axial and/or systemic metastases, and 4 were free of disease at 39 to 184 months. Univariate analysis revealed that gross total surgical resection was the most important prognostic factor predicting survival (44 versus 15 mo; P < 0.0001), followed by a long duration of symptoms (>1 yr; P = 0.005), young age at symptom onset (children versus adults; P = 0.045), and absence of necrosis (P = 0.02). Gross total surgical resection (P = 0.001) and a long duration of symptoms (symptoms > 1 yr; P = 0.013) proved to be independent and statistically significant prognostic factors in the multivariate analysis.

CONCLUSION

NFP immunostaining is required to identify MGNTs accurately. Their distinction from malignant gliomas is of paramount clinical importance, particularly for neurosurgeons, because gross total surgical resection may be curative in some cases. Finally, MGNTs may account for the long-term survival and/or occurrence of metastases demonstrated in a subset of malignant gliomas.

Pilomyxoid astrocytoma: diagnosis, prognosis, and management

Pilomyxoid astrocytoma (PMA) is a recently defined pediatric brain tumor; PMAs were previously classified within the pilocytic astrocytoma (PA) category. Nevertheless, PMA has different histological features and has been shown to behave more aggressively than PA. These findings indicate that PMA may be a unique entity that is distinct from PA, or it may be an unusual variant. To increase awareness of PMA within the neurosurgical community, the authors review the diagnostic criteria, prognostic implications, and current management of this recently described pediatric low-grade astrocytoma.

Management of pilocytic astrocytoma with diffuse leptomeningeal spread: two cases and review of the literature

INTRODUCTION

Leptomeningeal dissemination of juvenile pilocytic astrocytoma (JPA) is a rare event. We report two children with disseminated JPAs treated with a chemotherapeutic agent, temozolomide, after progression of the disease despite surgery, traditional chemotherapy, and/or radiation therapy.

CASE REPORTS

Patient 1 presented with hydrocephalus and progressive lower extremity weakness, and was found to have a suprasellar mass as well as extensive spinal disease. Ventriculoperitoneal shunting, decompressive laminectomy with spinal tumor debulking, and chemotherapy with carboplatin and vincristine were initially employed. However, disease progressed and craniospinal irradiation and temozolomide were used. Patient 1 remains in a fair condition today, 2 years later. Patient 2 presented at 8 months of age with failure to thrive. Imaging revealed a cystic lesion in the hypothalamic region with extensive subarachnoid metastatic disease to the spine. Biopsy was performed followed by chemotherapy with vincristine, cyclohexylchloroethylnitrosourea (CCNU), 6-TG, and procarbazine. Due to the continued progression of the disease, cytoreductive surgery was performed and her chemotherapeutic regimen was switched to temozolomide. Two years after initial presentation patient 2 is clinically much improved with stable residual disease.

DISCUSSION

We review the literature and discuss treatment strategies for this challenging disease.

Stereotactic radiotherapy for localized low-grade gliomas in children: final results of a prospective trial

PURPOSE

To evaluate the efficacy of stereotactic radiotherapy (SRT) for small, localized, pediatric brain tumors and to determine the patterns of failure.

METHODS AND MATERIALS

A total of 81 patients were enrolled in an institutional review board-approved prospective Dana-Farber Cancer Institute protocol between 1992 and 1998. Of the 81 patients, 50 had low-grade astrocytoma, 23 had residual or recurrent craniopharyngioma, 4 had posterior fossa ependymoma, and 4 had other histologic types. All patients underwent biopsy for diagnosis, with the exception of patients with neurofibromatosis and radiographic evidence of an optic system tumor. The neurocognitive outcome for all patients was also an endpoint of the study and will be reported separately. This report focused on the patients with low-grade gliomas only. Of the 50 patients, 26 were males and 24 females; the median age was 9 years (range, 2-26 years). The indications for treatment of patients with low-grade gliomas were progression during or after chemotherapy or progression after surgery alone. SRT was delivered using a dedicated 6-MV linear accelerator. Immobilization was accomplished with a removable head-frame. CT and MRI fusion was used for treatment planning. The target volume generally included the preoperative tumor plus a 2-mm margin for the planning target volume. The median collimator size was 47.25 mm (range, 30-60 mm). Three to nine arcs were used to deliver a mean total dose of 52.2 Gy in 1.8-Gy daily fractions.

RESULTS

With a median follow-up of 6.9 years (range, 0.9-10.2 years), the progression-free survival rate was 82.5% at 5 years and 65% at 8 years. The overall survival was 97.8% at 5 years and 82% at 8 years. Six patients had local progression. Two of the patients with local progression had pathologic progression to anaplastic astrocytoma 3 and 7 years after initial SRT. Five patients, all with optic system/hypothalamic primary tumors, developed central nervous system dissemination 1.0-7.4 years after SRT. One patient developed a presumed radiation-induced primitive neuroectodermal tumor 6 years after initial treatment. Six patients died, three of dissemination, two of progression to higher grade tumors, and one of a secondary radiation-induced tumor. All 6 cases of local progression were within the primary tumor bed at the time of progression and had received the full prescription dose. No marginal failures occurred.

CONCLUSION

Stereotactic radiotherapy provides excellent local control for children with small, localized low-grade glial tumors. Marginal failures have not been observed, supporting the use of limited margins to minimize late sequelae using stereotactic immobilization and planning techniques.

Multi focal Pilocytic Astrocytomas With Ependymal Differentiation in the Bilateral Medial Temporal Lobes-Case Report-

A 7-year-old boy presented with headache, visual disturbance, and psychomotor seizures persisting for 7 months. He had mild hemiparesis and homonymous hemianopia on the left. Neuroimaging showed bilateral temporal lobe masses with calcification and cysts. The right temporal mass was subtotally resected. The histological diagnosis was pilocytic astrocytoma with ependymal differentiation and a MIB-1 staining index of up to 8.0%. Postoperatively his hemiparesis and psychomotor seizures disappeared. Adjuvant chemotherapy consisting of carboplatin and vincristine was given followed by radiotherapy. Neuroimaging showed that the bilateral tumors had disappeared and showed no recurrence for 29 months after the diagnosis. Pilocytic astrocytoma usually presents as a solitary mass in the cerebellum or optic pathway with low proliferative activity, but should be included in the differential diagnosis of multifocal tumors arising in the bilateral temporal lobes. Ependymal differentiation with extremely high proliferative activity might be related to this unusual clinical presentation. Intensive treatment is recommended for patients with such specific neuroimaging and histological features.

Pediatric surgical neuro-oncology: current best care practices and strategies

Significant advances have been made in the diagnosis and treatment of childhood brain tumors. Gross total surgical resection combined with appropriate adjuvant therapies can achieve a high rate of disease control for low grade gliomas, ependymomas and medulloblastomas. High grade gliomas, tumors involving the optic apparatus or diencepahalic structures, diffuse brainstem lesions, and recurrent or metastatic disease still pose considerable therapeutic challenges. We review the current treatment strategies of the three most common types of pediatric brain tumors: gliomas, medulloblastomas and ependymomas, and discuss current and future diagnostic and therapeutic modalities.