Benign cerebellar astrocytomas in children

Cerebellar pilocytic astrocytoma: predictors of recurrence based on MRI morphology-a single-centre experience

PURPOSE

We aimed to present our surgical experience and the impact of a solid or cystic morphology of cerebellar pilocytic astrocytoma (cPA) on surgery and the risk for a re-resection.

METHODS

We retrospectively analyzed all children operated at our institution between 2009 and 2023 for cPA. Tumours were categorized into 4 groups: (i) cystic PA without cyst wall enhancement, (ii) cystic PA with cyst wall enhancement, (iii) solid tumour, (iv) and solid tumour with central necrosis.

RESULTS

Forty-two children with a median age at surgery of 7.1 years (range 0.7-14 years; male to female ratio 1.5) were identified. The median follow-up time was 3.1 years (0.6-14 years). Twenty-eight patients (66.6%) presented with cystic PA (20 without and 8 with cyst wall enhancement), 9 patients (21.4%) exhibited a solid tumour with central necrosis and 5 (11.9%) had a solid tumour without central necrosis. Gross total resection could be achieved in 31 patients (73.8%), near total resection in 6 (14.3%), and subtotal resection in 5 (11.9%). Progression occurred in 11 cases with 9 patients having a 2nd resection after a mean time of 3.4 years. The highest risk for a 2nd resection was seen in the group of solid tumours with a necrotic centre (odds ratio = 2.3), progression of enhancing cyst wall remnants was seen in one out of two patients with remnants needing reoperation.

CONCLUSION

Surgery in cerebellar PA should aim for gross total resection of the solid-enhancing tumour.

Long-term quality of survival after pediatric low-grade glioma

BACKGROUND

Low-grade glioma is the most common brain tumor in children with different modes of treatment and a high overall survival. Low-grade glioma is considered a chronic disease, since residual tumor is present in many children. The tumor and its treatment lead to acquired brain injury with diverse consequences for later life based on factors like the diverse tumor locations, treatment(s) applied, neurofibromatosis type 1, and age at diagnosis.

METHODS

An overview of affected domains is provided based upon cohort studies from literature and partially based on clinical experience with a practical approach regarding each domain of functioning in order to provide insight in the requirements for long-term care assistance after childhood low-grade glioma.

RESULTS

The diverse domains that can potentially be affected are described as follows: motor function, speech, eating and swallowing, sensory functions, seizures, neuropathy, organ function after systemic treatment, late effects due to cranial radiation (vascular changes and secondary tumors, endocrine and hypothalamic function, sleep and energy, neuro-cognition and education, psychosocial effects, and quality of life.

CONCLUSION

Insight in affected domains guides advices for medical follow-up, diagnostics, supportive instructions, and assistive measures per domain of functioning and provide insight in the requirements for long-term care assistance after childhood low-grade glioma.

Second-look surgery in postoperative pediatric low-grade glioma

OBJECTIVE

To review the literature on second-look surgery in pediatric low-grade gliomas (LGG) with a view to presenting both sides of the picture of re-exploration.

METHODS

Collection of material from recent literature on pediatric LGG. This was a retrospective review of these publications.

RESULTS

There are a number of publications recommending second-look surgery in selected cases, provided morbidity of the second surgery is minimum, and indeed some in which there is improvement in the neurodeficit after the second resection.

CONCLUSION

There seems a fair balance of articles recommending and dissuading the practice of second-look surgery, but in our limited experience we have found it useful in selected patients.

Precision based approach to tailoring radiotherapy in the multidisciplinary management of pediatric central nervous system tumors

Modern day survivorship from childhood malignancies is estimated to be over 80%. However, central nervous system tumors remain the leading cause of cancer mortality in children and is the most common solid tumor in this population. Improved survivorship is, in part, a result of improved multidisciplinary care, often with a combination of surgery, radiation therapy, and systemic therapy. With improved survival, long term effects of treatment and quality of life impacts have been recognized and pose a challenge to maximize the therapeutic ratio of treatment. It has been increasingly more apparent that precise risk stratification, such as with the inclusion of molecular classification, is instrumental in efforts to tailor radiotherapy for appropriate treatment, generally towards de-intensification for this vulnerable patient population. In addition, advances in radiotherapy techniques have allowed greater conformality and accuracy of treatment for those who do require radiotherapy for tumor control. Ongoing efforts to tailor radiotherapy, including de-escalation, omission, or intensification of radiotherapy, continue to improve as increasing insight into tumor heterogeneity is recognized, coupled with advances in precision medicine employing novel molecularly-targeted therapeutics.

When Pediatric Headaches Are Not Benign-Eye Findings

Headache is the most common neurologic complaint that presents to the pediatrician. While most headaches are benign in nature, patients must be carefully evaluated to rule out life- or vision-threatening causes. Non-benign etiologies of headache may exhibit ophthalmologic signs and symptoms that can help narrow the differential diagnosis. It is also important for physicians to know in what situations appropriate ophthalmologic evaluation is necessary, such as evaluating for papilledema in the setting of elevated intracranial pressure. In this article we discuss life- and/or vision-threatening etiologies of headache, including infection, autoimmune disease, cerebrovascular pathologies, hydrocephalus, intracranial neoplasia, and idiopathic intracranial hypertension, and their associated ophthalmologic manifestations. Due to less familiarity of the disease amongst primary care providers, we discuss pediatric idiopathic intracranial hypertension in more comprehensive detail.

The use of the sodium fluorescein and YELLOW 560 nm filter for the resection of pediatric posterior fossa lesions

PURPOSE

This study aimed to verify the feasibility, safety, and benefit of using fluorescein sodium (FL) and a YELLOW 560 nm filter in posterior fossa tumors in children.

METHODS

All cases of pediatric posterior fossa tumors that have undergone surgery using fluorescein (2018-2022) have been included and were examined retrospectively. In those cases where resection of the tumor was planned, a blinded neuroradiologist distinguished gross total resection and subtotal resection according to the postoperative MRI findings. The surgical report and medical files were reviewed regarding the intraoperative staining grade and adverse events. The grade of fluorescent staining of the targeted lesion was assessed as described in the surgical reports. The screening was conducted for any reference to the degree of fluorescent staining: "intense," "medium," "slight," and "no staining."

RESULTS

19 cases have been included. In 14 cases, a complete resection was initially intended. In 11 of these cases, a gross total resection could be achieved (78.6%). Staining was described as intense in most cases (58.8%). Except for yellow-colored urine, no side effects obviously related to FL were found throughout the observation period.

CONCLUSION

In combination with a specific filter, FL is a reliable, safe, and feasible tool in posterior fossa surgery in children.

The 2021 WHO Classification of Tumors of the Central Nervous System: An update on pediatric low-grade gliomas and glioneuronal tumors

The 2021 5th edition of the WHO Classification of Tumors of the Central Nervous System reflects the discovery of genetic alterations underlying many central nervous system (CNS) neoplasms. Insights gained from technologic advances and novel applications in molecular diagnostics, including next‐generation sequencing and DNA methylation‐based profiling, coupled with the recognition of clinicopathologic correlates, have prompted substantial changes to CNS tumor classification; this is particularly true for pediatric low‐grade gliomas and glioneuronal tumors (pLGG/GNTs). The 2021 WHO now classifies gliomas, glioneuronal tumors and neuronal tumors into 6 families, three of which encompass pLGG/LGNTs: “Pediatric type diffuse low‐grade gliomas,” “circumscribed astrocytic gliomas,” and “glioneuronal and neuronal tumors.” Among these are six newly recognized tumor types: “diffuse astrocytoma, MYB or MYBL1‐altered”; “polymorphous low grade neuroepithelial tumor of the young (PLNTY)”; “diffuse low‐grade glioma‐MAPK altered”; “Diffuse glioneuronal tumor with oligodendroglioma‐like features and nuclear clusters (DGONC)”; “myxoid glioneuronal tumor (MGT)”; and “multinodular and vacuolating neuronal tumor (MVNT).” We review these newly recognized entities in the context of general changes to the WHO schema, discuss implications of the new classification for treatment of pLGG/LGNT, and consider strategies for molecular testing and interpretation.

Outcome of Childhood Cerebellar Pilocytic Astrocytoma: A Series With 20 Years of Follow Up

Background: Cerebellar pilocytic astrocytoma (PCA) is one of the few CNS tumors that can be cured with gross-total removal (GTR). In this series, we had 39 patients diagnosed with cerebellar PCA, 27 patients (70%) had GTR, and mean follow-up period was 62 months with no tumor recurrence.

Objective: To assess the long-term outcome of childhood cerebellar PCA treated at our institute during the period 2000-2020 and to highlight our surgical protocol.

Methodology: Retrospective review of all patients under 18 years of age who were diagnosed with cerebellar PCA and had surgical excision between 2000 and 2020 at the Medical City of King Saud University.

Results: The study included 39 patients: 17 males and 22 females, the mean age was 8.4 years. Radiologically, the tumor was solid in eight patients, cystic in 15 patients, and mixed components were found in 16 patients. The lesion was located in the right cerebellar hemisphere in 12 patients, left cerebellar hemisphere in five patients, and midline 22 patients. The tumor size ranged from 2 to 7 cm in its greatest diameter, it was <5 cm in 13 patients and >5 cm in 26 patients. Thirty-one patients had preoperative hydrocephalus. GTR of the tumor was achieved in 27 patients and subtotal resection (STR) was done in 12 patients, 18 patients required permanent ventriculoperitoneal (V-P) shunt, and five patients had postoperative radiotherapy. Postoperative complications included infection in two patients, cerebellar mutism in two patients, and significant neurologic disability in four patients. The duration of follow-up ranged from 0 to 240 months (mean follow-up period: 62.0 months). The outcome at 10 years was good in 30 patients, fair in four patients, poor in four patients, and one patient died. Recurrence was documented in nine patients, seven of them had GTR and two had STR.

Conclusion: GTR, if achievable, is curative for childhood cerebellar PCA. Many posterior fossa surgical complications could be avoided with watertight dural closure. Although new dural substitutes are available we prefer using autologous grafts (pericranium). It is easy to harvest pericranial graft from the external ventricular drain (EVD) site. The insertion of EVD synchronously with GTR of the tumor and gradual weaning of EVD could avoid the insertion of V-P shunt.

The Utility of Intraoperative Magnetic Resonance Imaging in the Resection of Cerebellar Hemispheric Pilocytic Astrocytomas: A Cohort Study

BACKGROUND

The mainstay of treatment for cerebellar pilocytic astrocytomas in the pediatric population is surgery. The use of intraoperative magnetic resonance imaging (iMRI) as a surgical adjunct may lower the likelihood of reoperation. Studies have examined iMRI in heterogenous tumor populations, but few have looked at single pathologies.

OBJECTIVE

To compare iMRI vs non-iMRI for hemispheric cerebellar pilocystic astrocytomas, specifically looking at revision surgeries and residual disease in follow-up.

METHODS

Retrospective review of medical records for 60 sequential patients with cerebellar hemispheric pilocytic astrocytoma at a single institution was conducted. Thirty-two patients with cerebellar pilocytic astrocytoma underwent surgery without iMRI, whereas 28 patients underwent surgical resection with iMRI. All patients had at least 3-year follow-up.

RESULTS

There were no significant differences between the patient populations in age, tumor size, or need for cerebrospinal fluid diversion between groups. Operative time was shorter without iMRI (without iMRI 4.4 ± 1.3 hours, iMRI 6.1 ± 1.5, P = .0001). There was no significant difference in the patients who had repeat surgery within 30 days (9% without iMRI, 0% iMRI, P = .25), residual disease at 3 months (19% without iMRI, 14% iMRI, P = .78), or underwent a second resection beyond 30 days (9% without iMRI, 4% iMRI, P = .61). There were more total reoperations in the group without iMRI, although this did not reach significance (19% vs 4%, P = .11).

CONCLUSION

For hemispheric cerebellar pilocytic astrocytomas, iMRI tended to leave less residual and fewer reoperations; however, neither of these outcomes achieved statistical significance leaving utilization to be determined by the surgeon.

Paediatric posterior fossa tumour resection rates in a small volume centre: the past decade's experience

BACKGROUND

Paediatric brain tumour resection rates have been shown to correlate with outcome and, it is argued, are linked to operator volume and caseload. The British paediatric neurosurgery community has previously debated centralisation of paediatric neuro-oncology. At the 2018 British Paediatric Neurosurgery Group (BPNG) meeting, a commitment was made to prospectively collect tumour resection data at each Neurosurgical Unit (NSU). Here we review our prospectively-collected 10-year database of the three commonest paediatric posterior fossa tumours - astrocytomas, medulloblastomas and ependymomas.

MATERIALS AND METHODS

Our primary outcome was extent of resection (EOR) on post-operative MRI scans reviewed by neuro-radiologists. Secondary outcomes comprised neurosurgical morbidity including infection, need for cerebrospinal fluid (CSF) diversion and the occurrence of posterior fossa syndrome (PFS).

RESULTS

55 children had 62 operations, where our complete resection rates for pilocytic astrocytomas, medulloblastomas and ependymomas were 77%, 79% and 63%, respectively. Both our primary and secondary outcomes were in keeping with the published literature and we discuss here some of the factors which may contribute towards favourable outcomes in a small volume centre.

CONCLUSION

Our results suggest that small volume centres can expect equivalent results to larger volume NSUs with regards to paediatric brain tumour surgery. Continuing efforts nationally for data collection on resection rates and operative outcomes is a key step towards optimising management in these children.

Effect of radiation therapy on overall survival following subtotal resection of adult pilocytic astrocytoma

OBJECTIVE

Pilocytic astrocytoma (PCA) is a low-grade glioma that primarily presents in children, but can also present in adulthood. Ideal primary treatment for PCA is gross total resection. However, for patients who are only able to undergo subtotal resection, the optimal course of post-operative therapy remains unclear. We investigated the association of patient characteristics and radiation therapy (RT) with overall survival specifically for adult PCA patients who underwent subtotal tumor resection.

METHODS

Information on adult patients (age ≥18 years old) who underwent subtotal PCA resection between 2004 and 2016 was collected from the National Cancer Database (NCDB). A multivariate Cox proportional hazards model was utilized to determine factors associated with overall survival.

RESULTS

A total of 451 patients were identified. The mean age of our patient cohort was 36.8 years old, and the majority of patients (83.4%) did not receive RT following subtotal PCA resection. Overall median survival was >93.8 months. On multivariate analysis, patients who were older at diagnosis (hazard ratio [HR] = 1.04, 95% confidence interval [CI] = 1.02-1.06, p < 0.01), black (HR = 2.35, CI = 1.05-5.23, p = 0.037), had a Charlson/Deyo comorbidity score ≥ 1 (HR = 2.27, CI = 1.00-5.14, p = 0.049), or received RT during their initial treatment (HR = 3.77, CI = 1.77-8.03, p < 0.01) had a significantly higher risk of death following subtotal PCA resection.

CONCLUSION

Post-operative RT was associated with a significantly higher risk of death among adults who underwent subtotal PCA resection. Our findings provide support for further inquiry into the efficacy of RT within this patient population.

Pilocytic Astrocytoma: A Review of General, Clinical, and Molecular Characteristics

Pilocytic astrocytomas are the primary tumors most frequently found in children and adolescents, accounting for approximately 15.6% of all brain tumors and 5.4% of all gliomas. They are mostly found in infratentorial structures such as the cerebellum and in midline cerebral structures such as the optic nerve, hypothalamus, and brain stem. The present study aimed to list the main characteristics about this tumor, to better understand the diagnosis and treatment of these patients, and was conducted on search of the published studies available in NCBI, PubMed, MEDLINE, Scielo, and Google Scholar. It was possible to define the main histologic findings observed in these cases, such as mitoses, necrosis, and Rosenthal fibers. We described the locations usually most affected by tumor development, and this was associated with the most frequent clinical features. The comparison between the molecular diagnostic methods showed great use of fluorescent in situ hybridization, polymerase chain reaction (PCR), and reverse transcriptase-PCR, important techniques for the detection of BRAF V600E mutation and BRAF-KIAA1549 fusion, characteristic molecular alterations in pilocytic astrocytomas.

Multiple Lesions Accompanied by Postoperative Spontaneous Intracystic Hemorrhage in a Pediatric Patient with Pilocytic Astrocytoma

Pilocytic astrocytoma is the most common primary brain tumor in the pediatric population and has a classic imaging manifestation of a solitary, cyst-like mass with a strong contrast-enhancing mural nodule. Here, we report a case of multiple lesions in pilocytic astrocytoma in a pediatric patient accompanied by postoperative spontaneous intracystic hemorrhage. We describe the case of a 14-year-old female patient with a history of surgery for right cerebellar tumor 6 years ago. Computed tomography (CT) and magnetic resonance imaging showed cystic lesion with a mural nodule in the cerebellum and right retrothalamic area, suggesting a pilocytic astrocytoma. Emergency surgery was done. Pathology confirmed a pilocytic astrocytoma World Health Organization Grade 1. During postoperative course, clinical outcomes of the patient did not improve. Follow-up CT showed cystic remnant compressing the brain stem with spontaneous intracystic hemorrhage. The second surgery was done to evacuate the hemorrhage and to remove the cyst. Serial CT was made after the second surgery with no cyst growth nor hemorrhage present. Only three other pediatric multiple pilocytic astrocytomas have been reported previously, and there were only 11 publications about spontaneous intracystic hemorrhage in pediatric pilocytic astrocytoma. Our review of all previously reported cases found that the patients were predominantly male, and some had a history of neurofibromatosis type 1.

Predictive measures and outcomes of extent of resection in juvenile pilocytic astrocytoma

PURPOSE

The present study aims to determine the tumor-related, clinical, and demographic factors associated with extent of resection (EOR) and post-operative outcomes in JPA patients.

METHODS

All patients with JPA, identified from a single-center brain tumour data base, were included in this retrospective analysis. Pre-operative MRI scans were reviewed by a single neurosurgeon blinded to the EOR. JPA cases that exhibited no residual tumor post-operatively were assigned to the GTR group, all other tumors were assigned to the <GTR group. Tumor-related, clinical and demographic variables as well as perioperative morbidities were compared between both groups.

RESULTS

Of the 28 patients included, 15 had a GTR (46% male; median age: 7.5 years; range: 1.16-14.9) and 13 had <GTR (69.2% male; median age: 10.6 years; range: 0.66-17.68). Tumor location reached statistical significance, as there were significantly more cerebellar tumors in the GTR group (86.7%) compared to the <GTR group (38.5%) (p = 0.016). GTR cases had a significantly longer average follow-up interval (6.6 months) than <GTR cases (4.5 months) (p = 0.031). All demographic variables, clinical variables and tumor-related factors showed no significant differences between the two groups. There were no differences between GTR and <GTR cases in terms of perioperative outcomes.

CONCLUSIONS

This study shows other than location of the lesion in the cerebellum, demographic, clinical and tumor-related variables are not associated with EOR in children with JPA. GTR was associated with an extended follow-up interval but not with increased perioperative morbidities compared to those with <GTR.

Prone versus sitting position in pediatric low-grade posterior fossa tumors

PURPOSE

The choice between sitting and prone position to access the infratentorial space in a suboccipital craniotomy is still a matter of debate. The comparisons in terms of complications and outcome of both positions are scarce, and the pediatric population is indeed more infrequent in these in scientific reviews. In this paper, we assess intraoperative and postoperative complications and neurological outcome in pediatric patients undergoing posterior cranial fossa surgery for pilocytic astrocytoma in sitting and prone position respectively.

METHODS

We retrospectively analyzed 30 consecutive patients undergoing surgery for cerebellar pilocytic astrocytoma at the two neurosurgical units referring to the University of Padova Medical School from 1999 to 2017. Preoperative, intraoperative, and postoperative data were retrieved from our medical archives.

RESULTS

The statistical analysis did not show any differences between the two groups in terms of preoperative, intraoperative, and postoperative data. The neurological status at last follow-up was similar in both groups of patients.

CONCLUSIONS

Our results suggest that both sitting and prone position can be considered safe in suboccipital craniotomies. Further studies are needed to show if there are possible differences between these positions for other frequent pediatric tumors such as medulloblastomas and ependymomas.

Usefulness of perfusion- and diffusion-weighted imaging to differentiate between pilocytic astrocytomas and high-grade gliomas: a multicenter study in Japan

PURPOSE

Imaging findings of pilocytic astrocytoma (PA) vary widely, sometimes resembling those of high-grade glioma (HGG). This study aimed to identify the imaging parameters that can be used to differentiate PA from HGG.

METHODS

Altogether, 60 patients with PAs and 138 patients with HGGs were included in the study. Tumor properties and the presence of hydrocephalus, peritumoral edema, and dissemination were evaluated. We also measured the maximum relative cerebral blood flow (rCBF_max) and volume (rCBV_max) and determined the minimum apparent diffusion coefficient (ADC_min) in the tumor's solid components. The relative T1 (rT1), T2 (rT2), and contrast-enhanced T1 (rCE-T1) intensity values were evaluated. Parameters were compared between PAs and HGGs using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was also used to evaluate these imaging parameters. A value of P < .05 was considered to indicate significance.

RESULTS

Intratumoral hemorrhage and calcification were observed in 10.0% and 21.7% of PAs, respectively. The rCBF_max and rCBV_max values were significantly lower in PAs (0.50 ± 0.35, 1.82 ± 1.21) than those in HGGs (2.98 ± 1.80, 9.54 ± 6.88) (P < .0001, P = .0002, respectively). The ADC_min values were significantly higher in PAs (1.36 ± 0.56 × 10^-3 mm²/s) than those in HGGs (0.86 ± 0.37 × 10^-3 mm²/s) (P < .0001). ROC analysis showed that the best diagnostic performance was achieved with rCBF_max.

CONCLUSION

The rCBF_max, rCBV_max, and ADC_min can differentiate PAs from HGGs.

Securing Hemostasis in Pediatric Low-Grade Posterior Cerebral Fossa Tumors: The Value of Thrombin-Gelatin Hemostatic Matrix

PURPOSE

We report our preliminary experience concerning the use of thrombin-gelatin hemostatic matrix to strengthen the final hemostasis after posterior fossa low-grade tumor surgery in children. To our knowledge, this is the first report regarding the use of hemostatic matrix in pediatric neurosurgery.

MATERIALS AND METHODS

Between 2012 and 2016, twenty-three patients underwent posterior fossa surgery for low-grade gliomas in our department. The mean age was 6.35 years; 12 patients were female and 11 male. Histology revealed pilocytic astrocytoma in 15 cases, ependymoma in 7 cases, and gangliocytoma in 1 case. At the end of the surgery, effective hemostasis was achieved using standard methods and, in order to strengthen the final hemostasis, we used a thrombin-gelatin hemostatic matrix. In all of the cases a postoperative MRI was performed within 24 after the surgery; during hospitalization the patients underwent a clinical evaluation. Moreover, blood samples were taken to evaluate inflammatory parameters, hemoglobin, and sodium, and kidney and liver tests were performed according to the standard protocol.

RESULTS

The postoperative MRI did not show any complications imputable to the matrix. Dur ing radiological and clinical follow-up none of the patients showed any delayed complications related to the matrix.

CONCLUSIONS

In our practice we found thrombin-gelatin hemostatic matrix sealant to be a valid and safe tool for strengthening hemostasis in pediatric low-grade posterior fossa surgery.

Profound hearing loss following surgery in pediatric patients with posterior fossa low-grade glioma

Background

Hearing loss may occur in patients with posterior fossa low-grade glioma who undergo surgery.

Methods

We retrospectively reviewed 217 patients with posterior fossa low-grade glioma, including 115 for whom results of hearing tests performed after surgery and before chemotherapy or radiation therapy were available. We explored the association of UHL with age at diagnosis, sex, race, tumor location, extent of resection, posterior fossa syndrome, ventriculoperitoneal shunt placement, and histology.

Results

Of the 115 patients, 15 (13.0%: 11 male, 6 black, 8 white, 1 multiracial; median age 7 years [range, 1.3-17.2 years]) had profound UHL after surgery alone or before receiving ototoxic therapy. Median age at tumor diagnosis was 6.8 years (range, 0.7-14.1 years), and median age at surgery was 6.8 years (range, 0.7-14.1 years). Patients with UHL had pathology characteristic of pilocytic astrocytoma (n = 10), ganglioglioma (n = 4), or low-grade astrocytoma (n = 1). Of these 15 patients, 4 underwent biopsy, 1 underwent gross total resection, 1 underwent near-total resection, and 9 underwent subtotal resection. UHL was more frequent in black patients than in white patients (OR 7.3, P = .007) and less frequent in patients who underwent gross total resection or near-total resection than in those who underwent subtotal resection (OR 0.11, P = .02).

Conclusions

Children undergoing surgery for posterior fossa low-grade glioma are at risk for UHL, which may be related to race or extent of resection. These patients should receive postoperative audiologic testing, as earlier intervention may improve outcomes.

Hemorrhagic presentation of intracranial pilocytic astrocytomas: literature review

Pilocytic astrocytomas (PAs) are seemingly innocuous and benign tumors. However, in recent times, many case series have documented high rates of hemorrhage in these neoplasms. We hereby provide a detailed analysis on hemorrhagic pilocytic astrocytomas (HPA) in adults and report one such case managed at our institute. In addition, salient differences between adult and pediatric hemorrhagic PA have been briefed. Hospital records were retrieved for our case. Literature review was conducted by searching online databases for the following keywords-pilocytic astrocytoma, hemorrhage, cranial, pediatric, and adults. A 22-year-old male with neurofibromatosis-1 presented with sudden onset headache and vomiting of 3-day duration. Imaging revealed a lobulated suprasellar lesion with obstructive hydrocephalus. Pterional transsylvian approach and subtotal resection were performed. Histopathology showed features of PA with bleed. Including current report, a total of 26 cases have been reported. Mean age was 37 years (21-75 years) and they are mostly found in the third decade. The male:female ratio was 2.1:1. Sudden headache with vomiting was the most common symptoms. Tumors were mostly located in cerebral hemispheres (n = 9/34.6%), hypothalamus/suprasellar region (n = 7/27%), and cerebellum (n = 6/23%). Two-thirds underwent gross total excision. There were two deaths and except one case, no recurrences were reported in those with available follow-ups. Hemorrhagic presentation of a PA is rare, although more commonly seen in adults and most commonly located in cerebral hemispheres. Maximal safe resection is the standard treatment and recurrences are rare.

Clinicopathological Study of Pediatric Posterior Fossa Tumors

CONTEXT

Brain tumor is one of the most devastating forms of human illness, especially when occurring in the posterior fossa and involving the brainstem. Tumors in the posterior fossa are considered some of the most critical brain lesions. This is primarily due to the limited space within the posterior fossa, as well as the potential involvement of the vital brainstem nuclei.

AIMS

The aim of this study is to analyze the incidence, clinical features, surgical outcome, complications, and prognosis in a series of 37 pediatric patients with posterior fossa tumors who underwent surgery between September 2012 and January 2015 from the Department of Neurosurgery, King George Hospital, Visakhapatnam (both prospective and retrospective study).

MATERIALS AND METHODS

A series of 37 cases were treated by the Department of Neurosurgery, King George Hospital, between August 2012 and January 2015.

RESULTS

Posterior fossa tumors are predominantly seen in children with a peak incidence in the first decade. The most common presenting symptoms are raised intracranial pressure with headache and vomiting. Majority of the tumors are medulloblastomas, ependymomas, and cerebellar astrocytomas. The most common location is the cerebellar vermis, followed by the cerebellar hemispheres, followed by the forth ventricle and then the brainstem.

A Review of Visual and Oculomotor Outcomes in Children With Posterior Fossa Tumors

Tumors of the posterior fossa represent the most common solid malignancy of childhood and can affect the visual system in several ways. This article outlines the relevant visual anatomy affected by these tumors and reviews the visual and oculomotor outcomes associated with the following 3 most common tumor types-medulloblastoma, juvenile pilocytic astrocytoma, and ependymoma. The available data suggest that the rate of permanent vision loss is low (5.9%-8.3%), with patients having juvenile pilocytic astrocytoma demonstrating the best outcomes. The rate of long-term strabismus (25%-29.1%) and nystagmus (12.5%-18%) is higher and associated with significant morbidity.

Posterior Fossa Tumors

Pediatric brain tumors are the leading cause of death from solid tumors in childhood. The most common posterior fossa tumors in children are medulloblastoma, atypical teratoid/rhabdoid tumor, cerebellar pilocytic astrocytoma, ependymoma, and brainstem glioma. Location, and imaging findings on computed tomography (CT) and conventional MR (cMR) imaging may provide important clues to the most likely diagnosis. Moreover, information obtained from advanced MR imaging techniques increase diagnostic confidence and help distinguish between different histologic tumor types. Here we discuss the most common posterior fossa tumors in children, including typical imaging findings on CT, cMR imaging, and advanced MR imaging studies.

Principles of radiation therapy

Although resection remains the mainstay in the treatment of gliomas, microscopically complete resection of most central nervous system tumors remains challenging, and is, in fact, rarely accomplished. Considering their invasive nature, gross total resections to clearly negative margins often do or would require removal or transection of functional brain, with likely serious neurologic deficits. Consequently, radiotherapy has emerged as an indispensable component of therapy. It is delivered primarily by external-beam radiotherapy or brachytherapy techniques. Herein, we present the biologic principles, techniques, and applications of radiotherapy in glioma treatment today.

Spontaneous complete regression of hypothalamic pilocytic astrocytoma after partial resection in a child, complicated with Stevens-Johnson syndrome: a case report and literature review

Pilocytic astrocytoma (PA) is the most common pediatric central nervous system glial neoplasm and the most common pediatric cerebellar tumor. The spontaneous regression that occurs after partial/subtotal resection is multifactorial, depending on multiple factors, as for the case of humoral and cell-mediated immune responses of the host to the implanted tumor. A 7-year-old boy was referred to a neurosurgery clinic with headache. Further imaging workup revealed hypothalamic PA. Partial resection of the lesions was performed with right-side pterional approach. The patient developed a severe panmucositis [Stevens-Johnson syndrome (SJS)] and respiratory failure plus conjunctivitis, due to phenytoin allergy. During the patient's 6-month follow-up, postoperative magnetic resonance imaging (MRI) revealed a residual tumor, and about 9 months later (at 15 months postoperatively), the MRI showed total regression of the tumor. Clinically, symptomatic PA may undergo spontaneous regression after partial resection. We report a well-documented case of spontaneous regression hypothalamic PA after partial resection that complicated with SJS. Immune system reaction in SJS may have a role in tumor behavior and spontaneous regression. Multiple studies confirmed spontaneous regression in PA after partial/subtotal resection. This phenomenon occurs due to humoral and cell-mediated host immune responses to the implanted tumor. The immune system reaction in SJS may have a role in tumor behavior and spontaneous regression.

Transcriptional profiles of pilocytic astrocytoma are related to their three different locations, but not to radiological tumor features

Background

Pilocytic astrocytoma is the most common type of brain tumor in the pediatric population, with a generally favorable prognosis, although recurrences or leptomeningeal dissemination are sometimes also observed. For tumors originating in the supra-or infratentorial location, a different molecular background was suggested, but plausible correlations between the transcriptional profile and radiological features and/or clinical course are still undefined. The purpose of this study was to identify gene expression profiles related to the most frequent locations of this tumor, subtypes based on various radiological features, and the clinical pattern of the disease.

Methods

Eighty six children (55 males and 31 females) with histologically verified pilocytic astrocytoma were included in this study. Their age at the time of diagnosis ranged from fourteen months to seventeen years, with a mean age of seven years. There were 40 cerebellar, 23 optic tract/hypothalamic, 21 cerebral hemispheric, and two brainstem tumors. According to the radiological features presented on MRI, all cases were divided into four subtypes: cystic tumor with a non-enhancing cyst wall; cystic tumor with an enhancing cyst wall; solid tumor with central necrosis; and solid or mainly solid tumor. In 81 cases primary surgical resection was the only and curative treatment, and in five cases progression of the disease was observed. In 47 cases the analysis was done by using high density oligonucleotide microarrays (Affymetrix HG-U133 Plus 2.0) with subsequent bioinformatic analyses and confirmation of the results by independent RT-qPCR (on 39 samples).

Results

Bioinformatic analyses showed that the gene expression profile of pilocytic astrocytoma is highly dependent on the tumor location. The most prominent differences were noted for IRX2, PAX3, CXCL14, LHX2, SIX6, CNTN1 and SIX1 genes expression even within different compartments of the supratentorial region. Analysis of the genes potentially associated with radiological features showed much weaker transcriptome differences. Single genes showed association with the tendency to progression.

Conclusions

Here we have shown that pilocytic astrocytomas of three different locations can be precisely differentiated on the basis of their gene expression level, but their transcriptional profiles does not strongly reflect the radiological appearance of the tumor or the course of the disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1810-z) contains supplementary material, which is available to authorized users.

Pediatric cerebellar astrocytoma: a review

INTRODUCTION

Cerebellar astrocytomas (CA) are one of the most common posterior fossa tumors in children. The vast majority is low grade, and prognosis for long-term survival is excellent.

METHODS

Recent literature about CA was reviewed to provide an up to date overview of the epidemiology, pathology, molecular and cell biology, diagnosis, presentation, management, and long-term outcomes.

RESULTS

Surgical resection remains the first-line treatment with complete removal of the tumor the goal. However, even when only subtotal resection has been achieved, there is a significant chance that the tumor will remain stable or will regress spontaneously. Adjuvant chemotherapy is reserved for those tumors that progress despite surgery, and more personalized chemotherapy is being pursued with better understanding of the molecular genetics of this tumor. Radiotherapy has generally not been recommended, but stereotactic radiotherapy and conformal proton beam radiotherapy may be reasonable options in the setting of relapse or progression. In the long term, permanent neurologic deficits, mainly cerebellar dysfunction, are common, but quality of life and cognitive function are generally good.

CONCLUSIONS

Low-grade CA remains primarily a surgical disease, with excellent survival rates. Care must be taken with surgery and adjuvant treatments to preserve neurologic function to allow for optimal outcomes in the long term.

Morphological brain lesions of pediatric cerebellar tumor survivors correlate with inferior neurocognitive function but do not affect health-related quality of life

PURPOSE

We aimed to determine whether extent of morphological brain injury in pediatric cerebellar tumor survivors correlates with neurocognitive function and health-related quality of life (HrQoL).

METHODS

Seventeen cerebellar pilocytic astrocytoma (cPA) and 17 medulloblastoma (MB) survivors were examined for HrQoL, intelligence using the German version of the WISC-III, attention, working memory, and visual motor coordination. MRI scans were analyzed for extent of posterior fossa brain tissue loss.

RESULTS

We found significant correlations between amount and extent morphological brain lesions of pediatric cerebellar tumor survivors and several cognitive impairments including intelligence and attention in both patient groups. These were in total more pronounced in MB patients when compared to cPA patients. Still, function loss and brain lesions detected on conventional MRI did not influence HrQoL.

CONCLUSIONS

These findings support the notion that long-term neurocognitive deficits of pediatric posterior fossa tumor survivors significantly correlate with brain tissue damage. The cerebellum plays a role in regulating higher-order functions. On the contrary, the extent brain injury is not detected by HrQoL assessment.

Epilepsy associated tumors: Review article

Long-term epilepsy associated tumors (LEAT) represent a well known cause of focal epilepsies. Glioneuronal tumors are the most frequent histological type consisting of a mixture of glial and neuronal elements and most commonly arising in the temporal lobe. Cortical dysplasia or other neuronal migration abnormalities often coexist. Epilepsy associated with LEAT is generally poorly controlled by antiepileptic drugs while, on the other hand, it is high responsive to surgical treatment. However the best management strategy of tumor-related focal epilepsies remains controversial representing a contemporary issues in epilepsy surgery. Temporo-mesial LEAT have a widespread epileptic network with complex epileptogenic mechanisms. By using an epilepsy surgery oriented strategy LEAT may have an excellent seizure outcome therefore surgical treatment should be offered early, irrespective of pharmacoresistance, avoiding both the consequences of uncontrolled seizures as well as the side effects of prolonged pharmacological therapy and the rare risk of malignant transformation.

Manifestations of pilocytic astrocytoma: a pictorial review

BACKGROUND

Pilocytic astrocytoma can be challenging to diagnose.

METHODS

Its clinical presentations can differ, directly related to its size and location, and are relatively unreliable. Similarly, imaging findings also vary with the location of the pilocytic astrocytoma.

RESULTS

This review provides an overview of the different imaging findings regarding pilocytic astrocytomas using both conventional and advanced magnetic resonance imaging sequences according to tumour location; the findings are strongly related to the tumour's tendency to infiltrate surrounding structures, being able to carry out gross total resection, and finally the prognosis.

CONCLUSIONS

Knowledge of these imaging manifestations of pilocytic astrocytoma may be helpful to arrive at an accurate diagnosis.

TEACHING POINTS

• To recognise the various imaging findings of pilocytic astrocytoma on both conventional and advanced magnetic resonance imaging sequences. • To identify the characteristic imaging findings according to tumour location. • To discuss the relevant differential diagnoses of pilocytic astrocytoma in each tumour location.

[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.

Validation and modification of a predictive model of postresection hydrocephalus in pediatric patients with posterior fossa tumors

OBJECT

Postresection hydrocephalus is observed in approximately 30% of pediatric patients with posterior fossa tumors. However, which patients will develop postresection hydrocephalus is not known. The Canadian Preoperative Prediction Rule for Hydrocephalus (CPPRH) was developed in an attempt to identify this subset of patients, allowing for the optimization of their care. The authors sought to validate and critically appraise the CPPRH.

METHODS

The authors conducted a retrospective chart review of 99 consecutive pediatric patients who presented between 2002 and 2010 with posterior fossa tumors and who subsequently underwent resection. The data were then analyzed using bivariate and multivariate analyses, and a modified CPPRH (mCPPRH) was applied.

RESULTS

Seventy-six patients were evaluated. Four variables were found to be significant in predicting postresection hydrocephalus: age younger than 2 years, moderate/severe hydrocephalus, preoperative tumor diagnosis, and transependymal edema. The mCPPRH produced observed likelihood ratios of 0.737 (95% CI 0.526-1.032) and 4.688 (95% CI 1.421-15.463) for low- and high-risk groups, respectively.

CONCLUSIONS

The mCPPRH utilizes readily obtainable and reliable preoperative variables that together stratify children with posterior fossa tumors into high- and low-risk categories for the development of postresection hydrocephalus. This new predictive model will aid patient counseling and tailor the intensity of postoperative clinical and radiographic monitoring for hydrocephalus, as well as provide evidence-based guidance for the use of prophylactic CSF diversion.

Neurological morbidity of surgical resection of pediatric cerebellar astrocytomas

BACKGROUND

Review of children with low-grade cerebellar astrocytoma (LGCA) prior to 1992 showed a 98% rate of gross total resection (GTR) but a concerning incidence of permanent neurological dysfunction. The purpose of this study was to determine the rate of GTR of LGCA since 1992 and frequency of neurologic injury.

METHODS

Retrospective review of children with LGCA was performed. CT/MR scans were rereviewed to assess extent of resection. Primary outcomes included incidence of GTR and incidence of permanent new neurological deficits. Other outcomes included late effects severity score (LESS), Bloom score for functional status, and educational assessment.

RESULTS

Of 50 LGCA, GTR was achieved in 38 (76%) compared to 43 of 44 (98%) prior to 1992 (p < 0.004). Permanent new neurologic deficits from surgery occurred in 16% compared to 18% in the prior era (p = 0.61). For 35 patients operated on by the 2 surgeons in the prior study, 74% had GTR, with permanent neurological deficits in 8.6%. At latest follow-up, all patients were alive, 16% with residual tumor. LESS was two or less (mild or no deficit) in 94%. Bloom score was one or two (no or mild disability) in 90%. Eighty-six percent attended normal school.

CONCLUSIONS

Less aggressive resection of LGCA in children may reduce postoperative neurologic deficits in the hands of the same surgeons as in the prior study but not overall at our institution. The good long-term outcomes suggest that it may be appropriate to do incomplete resection rather than risk additional neurological deficit.

Pediatric brain tumors

Pediatric brain tumors are the most common solid tumor of childhood. This article focuses on the metabolic signature of common pediatric brain tumors using MR spectroscopic analyses.

Prognostic factors and survival patterns in pediatric low-grade gliomas over 4 decades

BACKGROUND

This study reports changes in long-term survival after the introduction of modern imaging in pediatric patients with low-grade gliomas (LGGs).

METHODS

Records from 351 consecutive pediatric patients diagnosed with LGG between 1970 and 2009 at Mayo Clinic Rochester were reviewed and divided into diagnosis before (group I: 1970 to 1989) and after (group II: 1990 to 2009) postoperative magnetic resonance imaging became regularly used in pediatric LGG.

RESULTS

Median progression-free survival (PFS) and overall survival (OS) were not reached. Overall, 10-year PFS was 62% and OS was 90%. On multivariate analysis, improved PFS was associated with gross total resection (GTR; P<0.0001) and postoperative radiation therapy (RT; P<0.0001). In those undergoing less than GTR, PFS was improved with RT, nearing rates of patients receiving GTR (P=0.12). On multivariate analysis, higher OS was associated with GTR (P<0.0001) and pilocytic histology (P=0.03). Group II had fewer headaches, fewer sensory/motor symptoms, less postoperative RT, and more GTRs. OS and PFS were not different between the groups.

CONCLUSIONS

This large series of pediatric LGG patients with long-term follow-up found no significant changes in OS or PFS over time. Overall, GTR was associated with improved OS and PFS. RT was associated with an improvement in PFS, with the greatest benefit seen in patients undergoing less than GTR.

Central nervous system tumors

Central nervous system tumors are the most frequent malignant tumor in children and the main cause of death in this age group after traffic accidents. The current estimates are that one adult in 2500 is a survivor of a brain tumor that occurred during childhood. These tumors are particularly heterogeneous in terms of histology/biology, treatment, and outcome. They share, however, a high risk of neurological and cognitive morbidity due to the disease itself and the treatment modalities (radiotherapy, surgery, and chemotherapy). Diagnosis is frequently delayed because symptoms are usually nonspecific at the beginning of the evolution. Posterior fossa is the most frequent site and the tumors present most frequently with signs of intracranial hypertension. Supratentorial tumors are more frequent in infants and in adolescents; seizures are not uncommon, especially for benign tumors. When adjuvant treatment is needed, radiotherapy is usually the mainstay apart from some histologies where chemotherapy may be sufficient: low-grade gliomas, desmoplastic medulloblastomas, malignant glial tumors in infants. Multidisciplinary care is best performed in tertiary care centers and should include early rehabilitation programs soon after surgery.

Pathological and molecular advances in pediatric low-grade astrocytoma

Pediatric low-grade astrocytomas are the most common brain tumors in children. They can have similar microscopic and clinical features, making accurate diagnosis difficult. For patients whose tumors are in locations that do not permit full resection, or those with an intrinsically aggressive biology, more effective therapies are required. Until recently, little was known about the molecular changes that drive the initiation and growth of pilocytic and other low-grade astrocytomas beyond the association of a minority of cases, primarily in the optic nerve, with neurofibromatosis type 1. Over the past several years, a wide range of studies have implicated the BRAF oncogene and other members of this signaling cascade in the pathobiology of pediatric low-grade astrocytoma. In this review, we attempt to summarize this rapidly developing field and discuss the potential for translating our growing molecular knowledge into improved diagnostic and prognostic biomarkers and new targeted therapies.

Long-term follow-up of the multicenter, multidisciplinary treatment study HIT-LGG-1996 for low-grade glioma in children and adolescents of the German Speaking Society of Pediatric Oncology and Hematology

The Hirntumorstudien (HIT)-LGG-1996 protocol offered a comprehensive treatment strategy for pediatric patients with low-grade glioma (LGG), ie, observation, surgery, adjuvant radiotherapy, and chemotherapy to defer the start of irradiation in young children. In this current study, we sought to determine clinical factors for progression and survival. Between October 1, 1996 and March 31, 2004, 1031 patients were prospectively recruited into an observation arm (n = 668) and a nonsurgical arm stratifying 12 months of vincristine-carboplatin chemotherapy (n = 216) and conventional radiotherapy/brachytherapy (n = 147) in an age-dependent manner. Median patient age was 6.9 years; 28 patients had diencephalic syndrome, 44 had dissemination, and 108 had neurofibromatosis type 1(NF-1). Main tumor location was the supratentorial midline (40.4%), and the main histology was pilocytic astrocytoma (67.9%). Following a median observation of 9.3 years, 10-year overall survival (OS) was 0.94 and 10-year event-free survival (EFS) was 0.47. Ten-year progression-free survival was 0.62 following radiotherapy and 0.44 following chemotherapy. Sixty-one of 216 chemotherapy patients received radiotherapy 0.3-8.7 years after initial diagnosis. By multivariate analysis, diencephalic syndrome and incomplete resection were found to be unfavorable factors for OS and EFS, age ≥11 years for OS, and supratentorial midline location for EFS. Dissemination, age <1 year, and nonpilocytic histology were unfavorable factors for progression following radiotherapy (138 patients); and diencephalic syndrome, dissemination, and age ≥11 years were unfavorable factors following chemotherapy (210 patients). NF-1 patients and boys experienced prolonged tumor stabilization with chemotherapy. A nationwide multimodal treatment strategy is feasible for pediatric LGG. Extended follow-up yielded results comparable to single-institution series for the treatment groups. Three-quarters of surviving chemotherapy patients have not yet received radiation therapy. Infants with or without diencephalic syndrome and dissemination bear the highest risk for death and progression following diagnosis or treatment.

Cyst with a mural nodule tumor of the brain

The purpose of this article is to illustrate the imaging findings of lesions that present as cyst with a mural nodule tumor (CMNT). CMNT is a subtype pattern of intra-axial enhancement in central nervous system tumors, typical of a variety of brain neoplasms, including, as the most common, hemangioblastoma, pilocytic astrocytoma, ganglioglioma and pleomorphic xanthoastrocytoma and as less common tanycytic ependymoma, intraparenchymal schwannoma, desmoplastic infantile ganglioglioma and cystic metastasis. A retrospective design was chosen given the rarity of CMNT. Relevant cases were obtained retrospectively to review the different lesions that can present with the appearance of CMNT.

Primary neurosurgery for pediatric low-grade gliomas: a prospective multi-institutional study from the Children's Oncology Group

BACKGROUND

Central nervous system neoplasms are the most common solid tumors in children, and more than 40% are low-grade gliomas. Variable locations, extent of resection, postoperative neurodiagnostic evaluation, and histology have confounded therapy and outcome.

OBJECTIVES

To investigate disease control and survival after surgery.

METHODS

A prospective natural history trial from 1991 to 1996 produced a subset of patients with low-grade gliomas managed by primary surgery and subsequent observation. Patients were evaluable if eligibility, tumor location, and extent of resection were confirmed by pathological diagnosis, preoperative and postoperative imaging, and the surgeon's report. Primary end points were overall survival (OS), progression-free survival (PFS), and postprogression survival.

RESULTS

Of 726 patients enrolled, 518 were fully evaluable for analysis. The 5- and 8-year OS rates were 97% ± 0.8% and 96% ± 0.9%, respectively, and PFS rates were 80% ± 1.8% and 78% ± 2.0%. In univariate analyses, histological type, extent of residual tumor, and disease site were significantly associated with PFS and OS. In multivariate analysis, gross total resection (GTR) without residual disease was the predominant predictor of PFS. In patients with limited residual disease, 56% were free of progression at 5 years.

CONCLUSION

GTR should be the goal when it can be achieved with an acceptable functional outcome. The variable rate of progression after incomplete resection highlights the need for new predictors of tumor behavior.

Management of posterior fossa gliomas in children

Brain tumours form the most common type of solid tumour in children and more that 50% of these are infratentorial. Cerebellar astrocytomas and brain stem gliomas are the commonest posterior fossa glial tumours in children. Cerebellar astrocytomas represent up to 10% of all primary brain tumours and up to 25% of posterior fossa tumors in children, with Low grade gliomas forming the commonest of the cerebellar gliomas. They commonly present with symptoms and signs of raised intracranial pressure due to obstructive hydrocephalus. Radiologically they may be solid or cystic with or without a mural nodule. Surgical excision is the mainstay of treatment and forms the most consistent factor influencing progression free and long term survival. While majority of the tumours are pilocytic astrocytomas, they may also be fibrillary astrocytomas or even high grade tumours. Tumour histology does not appear to be an independent factor in the prognosis of these children, and therefore no palliative treatment after surgery is advocated. Brain stem gliomas account for approximately 10% of all pediatric brain tumours. Cranial nerve signs, ataxia and cerebellar signs with or without symptoms and signs of raised intracranial pressure are classically described symptoms and signs. Radiographic findings and clinical correlates can be used to categorize brain stem tumours into four types: diffuse, focal, exophytic and cervicomedullary. Histologically most brain stem gliomas are fibrillary astrocytomas. Diffuse brain stem gliomas are the most commonly seen tumour in the brain stem. These lesions are malignant high grade fibrillary astrocytomas. Focal tumours of the brain stem are demarcated lesions generally less than 2 cms in size, without associated edema. Most commonly seen in the midbrain or medulla, they form a heterogeneous pathological group, showing indolent growth except when the lesion is a PNET. Dorsally exophytic tumours lie in the fourth ventricle, while cervicomedullary lesions are similar to spinal intramedullary tumours. Expanding lesions are the only lesions amenable for excision while infiltrative and ventral lesions are not.

Stereotactic brachytherapy with iodine-125 seeds for the treatment of inoperable low-grade gliomas in children: long-term outcome

PURPOSE

Resection is generally considered the gold standard for treatment of low-grade (WHO grades I and II) gliomas (LGGs) in childhood. However, approximately 30% to 50% of these tumors are inoperable because of their localization in highly eloquent brain areas. A few reports have suggested stereotactic brachytherapy (SBT) with implantation of iodine-125 ((125)I) seeds as a safe and effective local treatment alternative. This single-center study provides a summary of the long-term outcome after SBT in one of the largest reported patient series.

PATIENTS AND METHODS

All pediatric patients treated with SBT ((125)I seeds; cumulative therapeutic dose 50-65 Gy within 9 months) by our group for LGG with follow-up of more than 6 months were included. Clinical and radiologic outcome, time to progression, and overall survival were evaluated. Prognostic factors (age, sex, Karnofsky performance score, tumor volume, and histology) for survival and disease progression were investigated.

RESULTS

In all, 147 of 160 pediatric patients treated with SBT (from 1982 through 2009) were analyzed in detail. Procedure-related mortality was zero, and the 30-day morbidity was transient and low (5.4%). Survival rates at 5 and 10 years were 93%, and 82%, respectively, with no significant difference between WHO grades I and II tumors (median follow-up, 67.1 ± 57.7 months). Twenty-one (14.8%) of 147 patients presented with tumor relapse. The remaining 126 patients revealed complete response in 24.6%, partial response in 31.0%, and stable disease in 29.6%. Neurologic status improved (57.8%) or remained stable (23.0%). None of the evaluated factors had significant impact on the study's end points except tumor volume more than 15 mL, which caused significantly higher rates of tumor recurrence (P < .05).

CONCLUSION

We demonstrate that SBT represents a safe, minimally invasive, and highly effective local treatment option for pediatric patients with inoperable LGG WHO grades I and II.

Radiographically distinct variant of pilocytic astrocytoma: a case series

The imaging findings of pilocytic astrocytomas are classically described as a cyst with an enhancing mural nodule. We report 2 unusual cases of multicystic cerebellar midline masses that were proven to be pilocytic astrocytomas. The uniqueness of the imaging features in these cases may represent an important variant of pilocytic astrocytomas. Recognition of this variant may prevent an unnecessary workup to exclude other etiologies such as parasitic infection (ie, cysticercosis) or cystic metastatic disease.