Prognostic factors of CNS tumours in Neurofibromatosis 1 (NF1): a retrospective study of 104 patients

Microarray analyses reveal regional astrocyte heterogeneity with implications for neurofibromatosis type 1 (NF1)-regulated glial proliferation

Numerous studies have suggested that astrocytes in the central nervous system (CNS) exhibit molecular and functional heterogeneity. In this regard, astroglia from different CNS locations express distinct immune system, and neurotransmitter proteins, have varying levels of gap junction coupling and respond differently to injury. However, the relevance of these differences to human disease is unclear. As brain tumors in children arise in specific CNS locations, we hypothesized that regional astroglial cell heterogeneity might partly underlie the propensity for gliomas to arise in these areas. In this study, we performed high-density RNA microarray profiling on astrocytes from postnatal day 1 optic nerve, cerebellum, brainstem, and neocortex. We showed that astroglia from each region are molecularly distinct, and we were able to develop gene expression patterns that distinguish astroglia, but not neural stem cells, from these different brain regions. We next used these microarray data to determine whether brain tumor suppressor genes were differentially expressed in these distinct populations of astroglia. Interestingly, neurofibromatosis type 1 (NF1) gene expression was decreased at both the RNA and protein levels in neocortical astroglia relative to astroglia from the other brain regions. To determine the functional significance of this finding, we found increased astroglial cell proliferation in optic nerve, brainstem, and cerebellum, but not neocortex, following Nf1 inactivation in vitro and in vivo. These findings provide molecular evidence for CNS astroglial cell heterogeneity, and suggest that differences in tumor suppressor gene expression might contribute to the regional localization of human brain tumors.

Advances in the genetics of glioblastoma: are we reaching critical mass?

Glioblastoma is the most common and highest-grade brain tumor, causing over 10,000 deaths each year in the US alone. Given the resistance of this tumor to standard surgery, radiation and chemotherapy, an understanding of the underlying genetic lesions is vital. Recent efforts to comprehensively profile glioblastomas using the latest technologies, both by The Cancer Genome Atlas (TCGA) project and by other groups, are addressing this need. Some genetic aberrations in glioblastoma have been known for decades, but early output from the new profiling initiatives has further illuminated the relevant genetics in this disease. Some genetic lesions, such as TP53 mutation, NF1 deletion or mutation, and ERBB2 amplification, have been found to be more common than was previously reported. New and unexpected discoveries have also been made, such as frequent mutations of the IDH1 and IDH2 genes in secondary glioblastoma. We might be tempted to speculate that we are approaching a comprehensive knowledge of the genetic lesions involved in glioblastoma, although other major discoveries doubtless remain to be made. In addition, the complex task of incorporating our updated knowledge into new--and possibly personalized--therapies for patients with glioblastoma still lies ahead.

Phase II trial of conformal radiation therapy for pediatric low-grade glioma

PURPOSE

The use of radiotherapy in pediatric low-grade glioma (LGG) is controversial, especially for young patients. We conducted a phase II trial of conformal radiation therapy (CRT) to estimate disease control by using a 10-mm clinical target volume (CTV) margin.

MATERIALS AND METHODS

Between August 1997 and August 2006, 78 pediatric patients with LGG and a median age of 8.9 years (range, 2.2 to 19.8 years) received 54 Gy CRT by using a 10-mm CTV and by targeting with systematic magnetic resonance imaging (MRI) registration. Tumor locations were diencephalon (n = 58), cerebral hemisphere (n = 3), and cerebellum (n = 17). Sixty-seven patients had documented or presumed WHO grade 1 tumors, 25 patients had prior chemotherapy, and 13 patients had neurofibromatosis type 1.

RESULTS

During a median follow-up of 89 months, 13 patients experienced disease progression. One patient experienced marginal treatment failure, eight experienced local failures, and four experienced metastatic failure. The mean and standard error 5- and 10-year event-free (87.4% +/- 4.4% and 74.3% +/- 15.4%, respectively) and overall (98.5% +/- 1.6% and 95.9% +/- 5.8%, respectively) survival rates were determined. The mean and standard error cumulative incidences of local failure at 5 and 10 years were 8.7% +/- 3.5% and 16.4% +/- 5.4%, respectively. The mean and standard error cumulative incidence of vasculopathy was 4.79% +/- 2.73% at 6 years, and it was higher for those younger than 5 years of age (P = .0105) at the time of CRT.

CONCLUSION

This large, prospective series of irradiated children with LGG demonstrates that CRT with a 10-mm CTV does not compromise disease control. The results suggest that CRT should be delayed in young patients to reduce the risk of vasculopathy.

Optic-pathway glioma: natural history demonstrated by a new empirical score

The optic pathway glioma uniquely involves the optic pathway in a relatively constant pattern, allowing for recurrent measurements of its extent and comparison within patients with the same diagnosis. Its natural history, however, is unpredictable. We sought to formulate an empirical score to quantify optic-pathway involvement and disease course. The sample comprised 23 children with a diagnosis of optic-pathway glioma who attended a pediatric tertiary medical center from 1975-2004 and underwent at least two annual magnetic resonance imaging examinations over an average of 7 years. Each scan was evaluated for the larger diameters of intraorbital and retro-orbital parts of the optic nerve, chiasma, and optic tract. Findings were analyzed by time from diagnosis. In untreated children, tumors generally remained stable for about 3 years, and diminished thereafter. Children with neurofibromatosis-1 had a better course than children with sporadic disease. Young children fared similarly to older ones. Worse outcomes occurred in children who eventually required treatment; this group might have done better with earlier diagnosis, and requires careful follow-up. Our new empirical score can define the natural history of optic-pathway gliomas, and identify prognostic factors. It may help identify tumors in neurofibromatosis-1 children who potentially require treatment.

[Epidemiology of primary brain tumor]

Two main approaches are generally used to study the epidemiology of primary brain tumors. The first approach is to identify risk factors, which may be intrinsic or related to external causes. The second main approach is descriptive. Intrinsic factors potentially affecting risk include genetic predisposition and susceptibility, gender, race, birth weight and allergy. Radiation exposure is the main extrinsic factor affecting risk. A large body of work devoted, among others, to electromagnetic fields and especially cellular phones, substitutive hormonal therapy, pesticides, and diet have been published. To date, results have been discordant. Descriptive epidemiological studies have reported an increasing annual incidence of primary brain tumors in industrialized countries. The main reasons are the increasing age of the population and better access to diagnostic imaging. Comparing incidences from one registry to another is difficult. Spatial and temporal variations constitute one explanation and evolutions in coding methods another. In all registries, weak incidence of primary brain tumors constitute a very important limiting factor. Renewed interest from the neuro-oncological community is needed to obtain pertinent and essential data which could facilitate improved knowledge on this topic.

Posterior fossa neoplasm and PHACES syndrome: a case report

A 4-year-old girl with PHACES syndrome (posterior fossa brain malformations, hemangiomas, arterial anomalies, cardiac anomalies/coarctation of the aorta, eye abnormalities, and sternal clefting/supraumbilical raphe) developed a cerebellar pilocytic astrocytoma 18 months after resolution of her neck, ear, and thoracic hemangiomas. Because cutaneous hemangiomas may have involuted by the time a patient is diagnosed with a central nervous system neoplasm, it seems possible that in other such patients the association may have gone unrecognized. Cerebellar pilocytic astrocytoma may be a rare manifestation of the posterior fossa malformations of PHACES.

Using neurofibromatosis-1 to better understand and treat pediatric low-grade glioma

Relatively little is known about the seminal genetic events that trigger the development of low-grade gliomas in children. Genetically engineered mouse models of the neurofibromatosis-1-inherited tumor predisposition syndrome have identified key intracellular growth control pathways, defined the contribution of the tumor microenvironment to glioma growth, and helped researchers understand the genetic basis for glioma susceptibility. In addition, genetically engineered mouse low-grade glioma models have recently been used in preclinical therapeutic studies to evaluate the efficacy of particular biologically based therapies and to define outcome measures.

[Phacomatosis and genetically determined tumors: the transition from childhood to adulthood]

Phacomatoses, or neurocutaneous disorders, are a group of congenital and hereditary diseases characterized by developmental lesions of the neuroectoderm, leading to pathologies affecting the skin and the central nervous system. There is a wide range of pathologies affecting individuals at different moments of life. The genetics is variable: while neurofibromatosis 1 and 2, tuberous sclerosis and von Hippel-Lindau disease are all inherited as autosomal dominant traits, Sturge-Weber syndrome is sporadic. Other neurocutaneous disorders can be inherited as autosomal recessive traits (i.e., ataxia-telangiectasia), X-linked (i.e., incontinentia pigmenti) or explained by mosaicism (i.e., hypomelanosis of Ito, McCune-Albright syndrome). In this review, we discuss the major types of neurocutaneous disorders most frequently encountered by the neurosurgeon and followed beyond childhood. They include neurofibromatosis types 1 and 2, tuberous sclerosis, Sturge-Weber syndrome and von Hippel-Lindau disease. In each case, a review of the literature, including diagnosis, genetics and treatment will be presented. The lifespan of the disease with the implications for neurosurgeons will be emphasized. A review of cases, including both pediatric and adult patients, seen in neurosurgical practices in the Lille, France and Lausanne, Switzerland hospitals between 1961 and 2007 is presented to illustrate the pathologies seen in different age-groups. Because the genes mutated in most phacomatoses are involved in development and are activated following a timed schedule, the phenotype of these diseases evolves with age. The implication of the neurosurgeon varies depending on the patient's age and pathology. While neurosurgeons tend to see pediatric patients affected with neurofibromatosis type 1, tuberous sclerosis and Sturge-Weber syndrome, there will be a majority of adult patients with von Hippel-Lindau disease or neurofibromatosis type 2.

Preclinical cancer therapy in a mouse model of neurofibromatosis-1 optic glioma

Mouse models of human cancers afford unique opportunities to evaluate novel therapies in preclinical trials. For this purpose, we analyzed three genetically engineered mouse (GEM) models of low-grade glioma resulting from either inactivation of the neurofibromatosis-1 (Nf1) tumor suppressor gene or constitutive activation of KRas in glial cells. Based on tumor proliferation, location, and penetrance, we selected one of these Nf1 GEM models for preclinical drug evaluation. After detection of an optic glioma by manganese-enhanced magnetic resonance imaging, we randomized mice to either treatment or control groups. We first validated the Nf1 optic glioma model using conventional single-agent chemotherapy (temozolomide) currently used for children with low-grade glioma and showed that treatment resulted in decreased proliferation and increased apoptosis of tumor cells in vivo as well as reduced tumor volume. Because neurofibromin negatively regulates mammalian target of rapamycin (mTOR) signaling, we showed that pharmacologic mTOR inhibition in vivo led to decreased tumor cell proliferation in a dose-dependent fashion associated with a decrease in tumor volume. Interestingly, no additive effect of combined rapamycin and temozolomide treatment was observed. Lastly, to determine the effect of these therapies on the normal brain, we showed that treatments that affect tumor cell proliferation or apoptosis did not have a significant effect on the proliferation of progenitor cells within brain germinal zones. Collectively, these findings suggest that this Nf1 optic glioma model may be a potential preclinical benchmark for identifying novel therapies that have a high likelihood of success in human clinical trials.

Gliomas in neurofibromatosis type 1: a clinicopathologic study of 100 patients

There are few pathologic studies of gliomas in patients with neurofibromatosis type 1. We analyzed clinical and pathologic features of gliomas from 100 neurofibromatosis type 1 patients (57 men; 43 women). The median age at tumor diagnosis was 13 years (range, 4 months to 68 years). Most tumors were typical pilocytic astrocytoma (PA) (49%) or diffusely infiltrating astrocytoma (DA) (27%) that included World Health Organization Grades II (5%), III (15%), and IV (7%); others were designated as low-grade astrocytoma, subtype indeterminate (LGSI; 17%). Two pilomyxoid astrocytomas, 1 desmoplastic infantile ganglioglioma and 1 conventional ganglioglioma, were also identified. The tumors in 24 cases arose in the optic pathways and included PA (n = 14), LGSI (n = 4), DA (n = 4), pilomyxoid astrocytoma (n = 1), and ganglioglioma (n = 1). The prognoses of the PA and LGSI gliomas overall were generally favorable; there were no survival differences between PA and LGSI groups based on site, tumor size, mitotic activity, or MIB-1 labeling index. In the combined PA and LGSI group, age younger than 10 years and gross total resection were associated with an increased overall survival rate (p = 0.047 and 0.002, respectively). Compared with the combined group (PA + LGSI), patients with DA at all sites had decreased overall and recurrence-free survival times (p < 0.001 and p = 0.003, respectively). This study emphasizes the wide histologic spectrum of gliomas that occur in patients with neurofibromatosis type 1. Classic PA and LGSI are the most common, and most have favorable prognoses. By contrast, DAs are more aggressive, similar to those that arise sporadically.

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.

Management of optic-hypothalamic gliomas in children: still a challenging problem

Optic pathway-hypothalamic gliomas (OPHGs) are rare, often unresectable tumors that mostly occur in childhood. Their biological behavior is unpredictable, although they tend to follow an aggressive clinical course in infants and a benign course in children with neurofibromatosis type 1. Optimal management is still controversial. Nonprogressing OPHGs are usually followed by surveillance alone. Surgery is advocated for progressing tumors to decompress the optic pathways, obtain a quick relief from intracranial hypertension and allow histologic examination (when needed). The current trend is in favor of conservative surgical behavior, except for resectable tumors. Chemotherapy is increasingly used in the management of OPHGs, especially in infants, to delay radiotherapy. Carboplatin and vincristine are the most frequently used drugs, although several chemotherapeutic agents in different combinations are currently employed with good results. Radiotherapy is utilized in children over 5 years of age as an adjuvant or as an alternative to surgery. The prognosis of OPHGs is quite good, with regard to the overall survival rate (70-100% at 5 years), but less favorable in terms of late morbidity.

[Neurofibromatosis type 2]

INTRODUCTION

Neurofibromatosis 2 (NF2) is a rare autosomal dominant disease whose hallmark is the development of bilateral vestibular schwannomas.

STATE OF THE ART

Other features of NF2 include schwannomas, meningiomas, ependymomas, localized along the central nervous system, schwannomas of the peripheral nerves, cutaneous and ophthalmological manifestations. NF2 can be diagnosed in patients without bilateral vestibular schwannoma with sets of diagnostic criteria. Disease phenotype is variable among patients. Main negative prognostic factors are a young age at onset of symptoms and a high number of tumors at diagnosis. NF2 tumor suppressor gene encodes Merlin/Schwannomin, and is also involved in most sporadic schwannomas and meningiomas. Its functions remains largely unknown.

PERSPECTIVES AND CONCLUSIONS

Treatment and follow of NF2 patients up require oto-neurosurgical teams experienced in NF2. Yearly and life time surveillance is mandatory. A clinical screening protocol is suggested. Classically, only symptomatic lesions are to be treated. Some authors advocate an early proactive strategy against vestibular schwannoma in order to preserve hearing. When a treatment is advisable, surgery remains the treatment of choice for tumors. Auditory brainstem implant must be taken into account in hearing rehabilitation.

Multiple pilocytic astrocytomas of the cerebellum in a 17-year-old patient with neurofibromatosis type I

OBJECTIVE

Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic-optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1.

METHODS

Case report.

CONCLUSION

The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.

Presentation of childhood CNS tumours: a systematic review and meta-analysis

BACKGROUND

Suspicion of a CNS tumour is classically raised by symptoms of raised intracranial pressure, focal deficits (including seizures), or papilloedema. Development of guidelines is needed for the identification and referral of children who might have a CNS tumour. We did a systematic literature review and meta-analysis to identify the clinical presentation of childhood CNS tumours to provide evidence to support the development of guidelines to assist with the identification and referral for imaging of children who might have a central nervous system tumour.

METHODS

Medline, Embase, and PubMed were searched for cohort studies and case series in children, published between January, 1991, and August, 2005, detailing the symptoms and signs at diagnosis of a CNS tumour.

FINDINGS

74 papers (n=4171) met the inclusion criteria. 56 symptoms and signs at diagnosis were identified, ranked by frequency, and clustered according to age, anatomical criteria, and genetic criteria. The most frequent symptoms and signs at diagnosis were: headache (33%), nausea and vomiting (32%), abnormalities of gait and coordination (27%), and papilloedema (13%) for intracranial tumours; macrocephaly (41%), nausea and vomiting (30%), irritability (24%), and lethargy (21%) for children aged under 4 years with intracranial tumours; reduced visual acuity (41%), exophthalmia (16%), and optic atrophy (15%) for children with an intracranial tumour and neurofibromatosis; nausea and vomiting (75%), headache (67%), abnormal gait and coordination (60%), and papilloedema (34%) for posterior fossa tumours; unspecified symptoms and signs of raised intracranial pressure (47%), seizures (38%), and papilloedema (21%) for supratentorial tumours; headache (49%), abnormal eye movements (21%), squint (21%), and nausea and vomiting (19%) for central brain tumours; abnormal gait and coordination (78%), cranial nerve palsies (52%), pyramidal signs (33%), headache (23%), and squint (19%) for brainstem tumours; and back pain (67%), abnormalities of gait and coordination (42%), spinal deformity (39%), focal weakness (21%), and sphincter disturbance (20%) for spinal-cord tumours. Other features noted were weight loss, growth failure, and precocious puberty. Symptoms of raised intracranial pressure were absent in more than half of children with brain tumours. Other neurological features were heterogeneous and related to tumour location.

INTERPRETATION

Apart from raised intracranial pressure, motor and visual system abnormalities, weight loss, macrocephaly, growth failure, and precocious puberty also suggest presence of an intracranial tumour. Children with signs and symptoms that could result from a CNS tumour need a thorough visual and motor system examination and an assessment of growth and pubertal status. Occurrence of multiple symptoms and signs should alert clinicians to possible CNS tumours.

From the archives of the AFIP: Pediatric orbit tumors and tumorlike lesions: neuroepithelial lesions of the ocular globe and optic nerve

Tumors and tumorlike lesions of the globe and optic nerve in children represent a different histologic spectrum than in adults; the imaging appearances of these lesions reflect their pathologic features. Retinoblastoma is a tumor of infancy and the most common intraocular tumor in children. There are heritable and nonheritable forms. The most common clinical finding is leukocoria. The differential diagnoses of this sign include several nonneoplastic lesions: Persistent hyperplastic primary vitreous is a congenital persistence of an embryonic structure causing a retrolental mass. The primitive vasculature may produce a septum in the posterior chamber. Coats disease is a vascular malformation of the retina that produces a lipoproteinaceous subretinal exudate. The vascular malformation enhances with intravenous contrast material, and the fat-containing subretinal exudate does not. Larval endophthalmitis is a granulomatous reaction to the dead or dying larvae of Toxocara canis or T. cati. The most important feature that allows differentiation of retinoblastoma from these so-called pseudoretinoblastomas is the presence of calcification in the former. Medulloepithelioma has two histologic forms; the teratoid type may contain calcifications, but it usually arises anteriorly from the ciliary body rather than posteriorly from the retina. Optic nerve glioma is the most common tumor of the optic nerve in children and is frequently associated with neurofibromatosis type 1. These gliomas are usually pilocytic astrocytomas and cause fusiform enlargement of the nerve.

Optic pathway gliomas in neurofibromatosis-1: controversies and recommendations

Optic pathway glioma (OPG), seen in 15% to 20% of individuals with neurofibromatosis type 1 (NF1), account for significant morbidity in young children with NF1. Overwhelmingly a tumor of children younger than 7 years, OPG may present in individuals with NF1 at any age. Although many OPG may remain indolent and never cause signs or symptoms, others lead to vision loss, proptosis, or precocious puberty. Because the natural history and treatment of NF1-associated OPG is different from that of sporadic OPG in individuals without NF1, a task force composed of basic scientists and clinical researchers was assembled in 1997 to propose a set of guidelines for the diagnosis and management of NF1-associated OPG. This new review highlights advances in our understanding of the pathophysiology and clinical behavior of these tumors made over the last 10 years. Controversies in both the diagnosis and management of these tumors are examined. Finally, specific evidence-based recommendations are proposed for clinicians caring for children with NF1.

Rare syndromes

Dermatologists may also encounter patients presenting with skin lesions that reflect an underlying endocrine disorder not commonly seen in daily practice. Some of these endocrine disorders include glucagonoma, neurofibromatosis type 1, McCune-Albright syndrome, multiple endocrine neoplasia, the Carney complex, carcinoid tumors, and mastocytosis. The clinical syndrome classically associated with glucagonoma includes necrolytic migratory erythema, weight loss, diabetes mellitus, anemia, cheilitis, venous thrombosis, and neuropsychiatric symptoms. The hallmarks of neurofibromatosis type 1 are the multiple café-au-lait spots and associated cutaneous neurofibromas. Other presenting features include freckling, peripheral neurofibromas, Lisch nodules, bone abnormalities, tumors, neurologic abnormalities and hypertension. McCune-Albright syndrome is characterized by café-au-lait spots, polyostotic fibrous dysplasia, sexual precocity, and hyperfunction of multiple endocrine glands. Multiple endocrine neoplasia type 2A is characterized by medullary thyroid cancer, pheochromocytoma, and primary parathyroid hyperplasia. In some patients with multiple endocrine neoplasia type 2A, cutaneous lichen amyloidosis may also be present. Multiple endocrine neoplasia type 2B is characterized by medullary thyroid cancer and pheochromocytoma but not hyperparathyroidism. The syndrome also includes mucosal neuromas, typically involving the lips and tongue, intestinal ganglioneuromas and a marfanoid habitus. Multiple endocrine neoplasia type 1 is an autosomal dominant predisposition to tumors of the parathyroid glands (four-gland hyperplasia), anterior pituitary, and pancreatic islet cells; hence, the mnemonic device of the "3 Ps"; multiple cutaneous lesions (angiofibromas and collagenomas) are frequent in patients with multiple endocrine neoplasia type 1. Carney complex may be viewed as a form of multiple endocrine neoplasia because affected patients often have tumors of two or more endocrine glands, including primary pigmented nodular adrenocortical disease (some with Cushing's syndrome), pituitary adenoma, testicular neoplasms, thyroid adenoma or carcinoma, and ovarian cysts. Additional unusual manifestations include psammomatous melanotic schwannoma, breast ductal adenoma, and a rare bone tumor, osteochondromyxoma. Carcinoid syndrome is the term applied to a constellation of symptoms mediated by various humoral factors elaborated by some carcinoid tumors; the major manifestations are diarrhea, flushing, bronchospasm, and cardiac valvular lesions. Mast cell diseases include all disorders of mast cell proliferation. These diseases can be limited to the skin, referred to as "cutaneous mastocytosis," or involve extracutaneous tissues, called "systemic mastocytosis." Patients present with urticaria pigmentosa, mastocytoma, or diffuse cutaneous mastocytosis. Systemic involvement may be gastronintestinal, hematologic, neurologic, and skeletal.

State of the art chemotherapeutic management of pediatric brain tumors

CNS tumors are the most common solid tumor of childhood. This article will review current treatments for pediatric brain tumors; low-grade gliomas, high-grade gliomas, medulloblastomas and ependymomas. It will also highlight the treatments that are used for brain tumors in very young children and in children with recurrent brain tumors. The management of recurrent pediatric brain tumors unresponsive to standard therapy will be discussed. The agents used in this setting are mainly biological modifiers, which attempt to provide molecularly targeted therapy. Future directions of therapy for pediatric brain tumors are described. Future treatment paradigms will need to consider examining the use of multiple biological modifiers. Similarly, these agents will need to be examined in combination with cytotoxic chemotherapy. Finally, the future direction of pediatric neuro-oncology and the focus of the field as it battles pediatric brain tumors is discussed.

Second primary tumors in neurofibromatosis 1 patients treated for optic glioma: substantial risks after radiotherapy

PURPOSE

Optic pathway gliomas (OPGs) are the most common CNS tumor in neurofibromatosis 1 (NF1) patients. We evaluated the long-term risk of second tumors in NF1-related OPGs after radiotherapy.

PATIENTS AND METHODS

We reviewed 80 NF1 OPG patients from two NF1 clinics to evaluate the long-term risk of developing subsequent nervous system tumors, with or without radiotherapy.

RESULTS

Fifty-eight patients were assessable for second tumors. Nine (50%) of 18 patients who received radiotherapy after their OPGs developed 12 second tumors in 308 person-years of follow-up after radiotherapy. Eight (20%) of 40 patients who were not treated with radiotherapy developed nine tumors in 721 person-years of follow-up after diagnosis of their OPGs. The relative risk of second nervous system tumor after radiotherapy was 3.04 (95% CI, 1.29 to 7.15).

CONCLUSION

There is a significantly increased risk of second nervous system tumors in those NF1 patients who received radiotherapy for their OPGs, especially when treated in childhood. Thus radiotherapy should only be used if absolutely essential in children with NF1.

Therapeutic approaches and advances in pediatric stroke

Evidence-based therapeutic interventions for pediatric ischemic cerebrovascular disease are beginning to emerge. The primary therapeutic target is usually the pathological prothrombotic disturbance that underlies the majority of pediatric stroke. A battle between anticoagulation and anti-platelet therapies continues to provide controversy and is the inspiration for upcoming randomized trials. Supportive care and neuroprotective strategies are an important consideration in children with stroke. Attempts to determine the safety of acute thrombolytic interventions are also underway. Finally, unique medical and surgical treatments for specific diseases leading to stroke in children continue to evolve. After briefly summarizing the epidemiology, pathophysiology, diagnosis, and outcomes of ischemic strokes in children, treatment approaches and alternatives will be reviewed in detail with emphasis placed on current areas of controversy and future directions for clinical research.

Malignant transformation and new primary tumours after therapeutic radiation for benign disease: substantial risks in certain tumour prone syndromes

In recent years the use of radiation treatment for benign tumours has increased with the advent of stereotactic delivery and, in particular, single high dose gamma knife therapy. This has been particularly true for benign CNS (central nervous system) tumours such as vestibular schwannoma, meningioma, pituitary adenoma, and haemangioblastoma. While short term follow up in patients with isolated tumours suggests this treatment is safe, there are particular concerns regarding its use in childhood and in tumour predisposing syndromes. We have reviewed the use of radiation treatment in these contexts with particular regard to malignant transformation and new tumour induction. This review indicates that much more caution is warranted regarding the use of radiation treatment for benign tumours in childhood and in tumour prone conditions such as the neurofibromatoses.

Pilomyxoid astrocytoma in a patient with neurofibromatosis

Pilomyxoid astrocytoma (PMA), a recently described variant of low-grade astrocytoma is associated with a high rate of recurrence and a propensity for CSF seeding. While cases of PMA have been reported in infants and young children, there has been no report of PMA in patients with neurofibromatosis. The first reportable case of PMA occurring in a child with neurofibromatosis type 1 (NF1) is described. Following presentation with obstructive hydrocephalus, the patient underwent a partial resection of a third ventricular tumor. Histology confirmed the typical features of PMA. The patient demonstrated a partial response to chemotherapy. The authors review the literature on PMA and discuss the specific issues associated with this diagnosis in the context of a child with neurofibromatosis.

Neurofibromatosis-associated nerve sheath tumors

In this paper the authors describe a patient with neurofibromatosis Type 1 (NF1) who presented with sequelae of this disease. They also review the current literature on NF1 and NF2 published between 2001 and 2005.

The method used to obtain information for the case report consisted of a family member interview and a review of the patient's chart. For the literature review the authors used the search engine Ovid Medline to identify papers published on the topic between 2001 and 2005. Neurofibromatosis Type 1 appears in approximately one in 2500 to 4000 births, is caused by a defect on 17q11.2, and results in neurofibromin inactivation. The authors reviewed the current literature with regard to the following aspects of this disease: 1) diagnostic criteria for NF1; 2) criteria for other NF1-associated manifestations; 3) malignant peripheral nerve sheath tumors (PNSTs); 4) the examination protocol for a patient with an NF1-related NST; 5) imaging findings in patients with NF1; 6) other diagnostic studies; 7) surgical and adjuvant treatment for NSTs and malignant PNSTs; and 8) hormone receptors in NF1-related tumors. Pertinent illustrations are included.

Neurofibromatosis Type 2 occurs much less frequently than NF1, that is, in one in 33,000 births. Mutations in NF2 occur on 22q12 and result in inactivation of the tumor suppressor merlin. The following data on this disease are presented: 1) diagnostic criteria for NF2; 2) criteria for other NF2 manifestations; 3) malignant PNSTs in patients with NF2; 4) examination protocol for the patient with NF2 who has an NST; and 5) imaging findings in patients with NF2. Relevant illustrations are included.

It is important that neurosurgeons be aware of the sequelae of NF1 and NF2, because they may be called on to treat these conditions.

Neurocutaneous syndromes: behavioral features

Neurocutaneous syndromes are disorders characterized by a neurological abnormality and cutaneous manifestations. Three of the more common neurocutaneous syndromes are Sturge-Weber syndrome, tuberous sclerosis, and neurofibromatosis. This review focuses on the cognitive and behavioral features of these syndromes.

Inherited Susceptibility for Pediatric Cancer

The percentage of childhood cancers that are caused by a clearly inherited predisposition varies significantly from only a few percent to more than 50% with individual tumor types. Recent advances in genetic testing and studies of cohorts of cancer patients have demonstrated the likelihood of identifying a cancer susceptibility mutation for numerous childhood cancers. Inherited predisposition to cancer is frequently the result of dominant constitutional mutations in tumor suppressor genes, which can be inherited from an affected parent or occur de novo during gametogenesis. In this article, we review the childhood malignancies that are associated with at least a 10% likelihood of being caused by a genetic susceptibility to cancer and therefore warrant consideration for a genetic evaluation; these malignancies include retinoblastoma, adrenocortical carcinoma, atypical teratoid and malignant rhabdoid tumors, optic pathway tumors, juvenile myelomonocytic leukemia, malignant peripheral nerve sheath tumors, vestibular schwannomas, endolymphatic sac tumors, hemangioblastomas, medullary thyroid cancer, pheochromocytomas, and paragangliomas. Children with other malignancies may also warrant genetic evaluation if there is the co-occurrence of malignancy and two or more congenital anomalies, or malignancy and a significant family history of related cancers. We also review the importance of the correct genetic diagnosis in order to ensure appropriate treatment and ongoing cancer surveillance for the child with cancer and closely related family members (e.g., parents and siblings).

Brain stem glioma: two case studies

The paths taken by each family in coming to terms with the dismal prognosis associated with brain stem glioma can be quite different. The case studies of 2 school-age girls diagnosed with a brain stem glioma within weeks of each other are presented. The multi-disciplinary team response to each family was individualized at each stage of diagnosis, treatment, and end-of-life care, as expected. The ultimate chronologic union of these 2 families as each child neared death was somewhat uncanny. The experience of each family, and their relationship with the team through this process, was an intense challenge and learning experience.

Natural history of neurofibromatosis 1-associated optic nerve glioma in mice

Children affected with the inherited tumor predisposition syndrome, neurofibromatosis 1 (NF1), are prone to the development of low-grade astrocytic optic pathway tumors (optic pathway glioma [OPG]). Previously, we developed a model of NF1-associated astrocytoma (GFAPCre; Nf1(flox/mut) mice) in which mice develop optic nerve and chiasm glioma. To define the molecular pathogenesis of OPG, we used this mouse model to study the natural history of OPG formation using immunohistological and radiographic approaches. We observed that whereas astrocyte hyperplasia is present in the optic nerves associated with gross optic nerve thickening at 3 weeks of age, overt neoplastic changes were not seen until 2 months of age. Astrocyte proliferation was maximal between 3 weeks and 2 months of age, suggesting that the most rapid period of growth occurs early. Mouse OPG tumors were detected by magnetic resonance imaging at 2 months of age and exhibited contrast enhancement, as seen in human OPG. In addition, the mouse OPG tumors exhibited expression of proteins associated with astroglial progenitors, including nestin and brain lipid binding protein. Last, we observed neovascularization and microglial cell infiltration by 3 weeks of age before overt neoplastic transformation, suggesting that these cellular changes participate in the early stages of tumor formation.

Toward the definition of cerebral arteriopathies of childhood

PURPOSE OF REVIEW

To facilitate and standardize the diagnosis of cerebrovascular conditions in childhood, particularly in the field of arterial ischemic diseases.

RECENT FINDINGS

Progress in diagnostic techniques in the past decade have led to newly established etiologies for childhood stroke, most of which represent some form of vascular pathology. These advances must be integrated into a modern nomenclature system with revised definitions of stroke and arterial wall diseases-arteriopathies-in childhood.

SUMMARY

This nomenclature system is intended to facilitate and enhance clinical research in childhood stroke, particularly multicenter collaborative studies.

Pediatric brain MRI in neurofibromatosis type I

Neurofibromatosis (NF) is the most common of the phakomatoses, with a prevalence of 1 in 3-4,000. Many organ systems can be affected. In addition to multiple peripheral neurofibromas, NF I predisposed to CNS tumors including optic glioma, astrocytoma and plexiform neurofibroma. The purpose of this pictorial review is to illustrate characteristic brain MR imaging lesions in children with NF I and to give some recommendations about diagnostic imaging procedures in children suffering from NF I. Typical findings in brain MRI are hyperintense lesion on T2-weighted images, so-called unknown bright objects, which may be useful as an additional imaging criterion for NF I. Contrast administration is necessary in MR studies to maximize tumor detection and characterization, to add confidence to the diagnosis of benign probable myelin vacuolization, and to document stability of neoplasm on follow-up examinations. We recommend to perform serial MR imaging in children every 12 months. The frequency of follow-up in children with known brain tumors will vary with the tumor grade, biological activity and treatment.

Neuroimaging findings in neurofibromatosis type 1 and 2

Neuroimaging, particularly MR imaging, plays an important role in the diagnosis and management of the patient with neurofibromatosis type 1 and 2. These phakomatoses are complex disorders affecting multiple cell types and multiple systems of the body with a wide range of expression. This article summarizes the neuroradiologic central nervous system findings in these neurocutaneous disorders.