Management of pilocytic astrocytoma

Adult-Onset Pilocytic Astrocytoma Predilecting Temporal Lobe: A Brief Review

(1) Introduction: Adult-onset pilocytic astrocytoma (APA) accounts for only 1.5% of all brain tumors, and studies regarding APA are limited. This review is focused on the history, clinical course, cytogenetics, neuroimaging features, management, and outcome of APAs. (2) Methods: Using a systematic search protocol in Google Scholar, PubMed, and Science Direct databases, the authors extracted cases of APA predilecting the temporal lobe from inception to December 2020. Articles lacking necessary data were excluded from this study. Data were analyzed using IBM SPSS 23 statistical package software. (3) Results: A total of 32 patients, 14 (43.8%) males and 18 (56.2%) females, with a male/female ratio of 0.77/1, were grouped. The mean age of the patients was 34.22 ± 15.17 years, ranging from 19 to 75. The tumors were predominantly located in the left side. We have also discussed the clinical presentation, and headache was the most common complaint, followed by visual disturbance. Preoperative neuroimaging features demonstrated cystic lesions in 16 patients, with mural nodule in 5 patients; intracerebral hemorrhage was present in 1 patient, and solid enhancing mass was observed in 3 patients. Only our reported case presented as a solid calcified mass. Most of the patients (78.1%) underwent a gross total resection (GTR), only 5 (21.9%) underwent subtotal resection (STR). The outcome and prognosis history were excellent, and no recurrence was observed. (4) Conclusion: Most of the APAs of the temporal lobe follow benign clinical courses, but some patients exhibit aggressive clinical behavior. There was no history of recurrence after treatment at up to 27 years of follow-up.

Concise review of radiosurgery for contemporary management of pilocytic astrocytomas in children and adults

Pilocytic astrocytoma (PA) may be seen in both adults and children as a distinct histologic and biologic subset of low-grade glioma. Surgery is the principal treatment for the management of PAs; however, selected patients may benefit from irradiation particularly in the setting of inoperability, incomplete resection, or recurrent disease. While conventionally fractionated radiation therapy has been traditionally utilized for radiotherapeutic management, stereotactic irradiation strategies have been introduced more recently to improve the toxicity profile of radiation delivery without compromising tumor control. PAs may be suitable for radiosurgical management due to their typical appearance as well circumscribed lesions. Focused and precise targeting of these well-defined lesions under stereotactic immobilization and image guidance may offer great potential for achieving an improved therapeutic ratio by virtue of radiosurgical techniques. Given the high conformality along with steep dose gradients around the target volume allowing for reduced normal tissue exposure, radiosurgery may be considered a viable modality of radiotherapeutic management. Another advantage of radiosurgery may be the completion of therapy in a usually shorter overall treatment time, which may be particularly well suited for children with requirement of anesthesia during irradiation. Several studies have addressed the utility of radiosurgery particularly as an adjuvant or salvage treatment modality for PA. Nevertheless, despite the growing body of evidence supporting the use of radiosurgery, there is need for a high level of evidence to dictate treatment decisions and establish its optimal role in the management of PA. Herein, we provide a concise review of radiosurgery for PA in light of the literature.

Genetic and histopathological associations with outcome in pediatric pilocytic astrocytoma

OBJECTIVE

Pilocytic astrocytomas (PAs) have a generally favorable prognosis; however, progression or recurrence after resection is possible. The prognostic value of histopathological qualifiers (defined below) or BRAF alterations is not well understood. The aim of this study was to identify the prognostic value of genetic and histopathological features of pediatric PAs.

METHODS

Patients treated for a WHO grade I PA at a single institution were analyzed for histopathological and genetic features and outcomes. "Histopathological qualifier" refers to designations such as "WHO grade I PA with increased proliferative index." BRAF alterations include gene fusions and point mutations. Patients with neurofibromatosis type 1 were excluded.

RESULTS

A total of 222 patients were analyzed (51% female, mean age 9.6 years). Tumors were located in the cerebellum/fourth ventricle (51%), optic pathway/hypothalamus (15%), brainstem (12%), and cerebral cortex (11%). BRAF alterations were screened for in 77 patients and identified in 56 (73%). Histopathological qualifiers were present in 27 patients (14%). Resection was performed in 197 patients (89%), 41 (21%) of whom displayed tumor progression or recurrence after resection. Tumor progression or recurrence was not associated with histopathologic qualifiers (p = 0.36) or BRAF alterations (p = 0.77). Ki-67 proliferative indices were not predictive of progression or recurrence (p = 0.94). BRAF alterations, specifically KIAA1549 fusions, were associated with cerebellar/fourth ventricular tumor location (p < 0.0001) and younger patient age (p = 0.03). Patients in whom gross-total resection was achieved had lower rates of progression and recurrence (p < 0.0001).

CONCLUSIONS

Histopathological features/qualifiers and BRAF alterations were not associated with tumor recurrence/progression in pediatric PAs. The extent of resection was the only factor analyzed that predicted outcome.

Recurrent adult pilocytic astrocytoma presenting with intraventricular and leptomeningeal spread

Background

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

Case Description

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

Conclusion

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

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.

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.

SYK inhibition blocks proliferation and migration of glioma cells and modifies the tumor microenvironment

Background

Glioblastoma (GBM) is one of the most aggressive human brain tumors, with a median survival of 15-18 months. There is a desperate need to find novel therapeutic targets. Various receptor protein kinases have been identified as potential targets; however, response rates in clinical studies have been somewhat disappointing. Targeting the spleen tyrosine kinase (SYK), which acts downstream of a range of oncogenic receptors, may therefore show more promising results.

Methods

Kinase expression of brain tumor samples including GBM and low-grade tumors were compared with normal brain and normal human astrocytes by microarray analysis. Furthermore, SYK, LYN, SLP76, and PLCG2 protein expressions were analyzed by immunohistochemistry, western blot, and immunofluorescence of additional GBM patient samples, murine glioma samples, and cell lines. SYK was then blocked chemically and genetically in vitro and in vivo in 2 different mouse models. Multiphoton intravital imaging and multicolor flow cytometry were performed in a syngeneic immunocompetent C57BL/6J mouse GL261 glioma model to study the effect of these inhibitors on the tumor microenvironment.

Results

SYK, LYN, SLP76, and PLCG2 were found expressed in human and murine glioma samples and cell lines. SYK inhibition blocked proliferation, migration, and colony formation. Flow cytometric and multiphoton imaging imply that targeting SYK in vivo attenuated GBM tumor growth and invasiveness and reduced B and CD11b+ cell mobility and infiltration.

Conclusions

Our data suggest that gliomas express a SYK signaling network important in glioma progression, inhibition of which results in reduced invasion with slower tumor progression.

Novel Surgical and Radiologic Risk Factors for Progression or Recurrence of Pediatric Pilocytic Astrocytoma

INTRODUCTION

Pilocytic astrocytomas (PA) are a common, benign childhood tumor known for their slow growth rates and excellent prognosis. The aim of our study was to characterize patient, tumor, and imaging-related risk factors for recurrence and progression of disease.

METHODS

We identified 116 patients with PA who underwent surgery at our institution between 2000 and 2015. Data were collected retrospectively from the clinical charts.

RESULTS

The mean age at resection was 7 ± 5 years (range 0.5-31) and mean follow-up was 6 ± 3 years. Initial resection was complete in 33 patients (29%), subtotal in 78 patients (67%), and biopsy in 5 patients (4%). A total of 45/116 (40%) patients experienced either recurrence or progression after initial resection with a mean time to recurrence or progression of 2.2 years. Bivariate analysis identified subtotal resection, tumor location, age at diagnosis, and imaging features (i.e., T2 invasion, exophytic component, hemorrhage, and solid tumors) as factors significantly associated with recurrence or progression (p < 0.05). Conversely, PAs that were completely resected, predominately cystic, and located in the cerebellum were significantly associated with no recurrence or progression (p < 0.05). Multivariate regression analysis narrowed down 4 robust risk factors: extent of resection, T2 invasion, predominantly solid lesions, and presence of an exophytic component (p < 0.05).

CONCLUSION

Total surgical removal of PA has been the most important prognostic factor for the clinical course of PA. Our study reveals additional risk factors for the recurrence or progression of disease: tumor invasion, solid composition, and tumors with an exophytic component.

Proliferative Index in Pediatric Pilocytic Astrocytoma by Region of Origin and Prediction of Clinical Behavior

BACKGROUND/AIMS

Pilocytic astrocytomas are common pediatric tumors. Molecular profiles vary with location of origin. Comparisons of proliferation have not been reported. We sought to identify differences in growth by region and whether these predict clinical behavior.

METHODS

A retrospective review of all patients undergoing surgery for a pilocytic astrocytoma at Children's Hospital LA from 2003 to 2015 was completed. Tumor location, determined by imaging, was stratified into infratentorial, supratentorial, or optic pathway. Proliferation was measured by Ki-67 immunostaining. A p value of 0.05 was deemed significant.

RESULTS

77 patients were identified. 51 had posterior fossa tumors, 12 had supratentorial tumors, and 14 had optic pathway tumors. Mean Ki-67 score was 3.67, 4.09, and 3.83%, respectively (p = 0.82). Ki-67 of ≥4% trended towards recurrence (p = 0.11), incomplete resection (p = 0.15), and younger age at presentation (p = 0.04). Ki-67 was weakly correlated with shorter survival after surgery (r = -0.103, p = 0.41). Partial resection strongest predicted recurrence (p < 0.001; OR = 13.0).

CONCLUSION

Proliferative index does not change by location. Higher cell proliferation was seen in younger patients and associated with shorter time to and a higher risk of recurrence. Further study is needed to identify predictors for clinical behavior. Importance of Study: This study provides a detailed analysis of the proliferative indices of tumors arising from characteristic locations within the brain. With recent advances in our understanding of the differences in molecular and genetic profiles despite similar histologic diagnoses, we felt that it was important to review whether there were unique components of tumor behavior that could be identified. In turn, we sought to determine whether tumor behavior could be used to predict the clinical course. This knowledge is important, given that not every tumor may undergo complete surgical resection, and that some lesions may require more aggressive upfront adjuvant therapy or be closely monitored for recurrence.

Application of fluorescein sodium in the resection of vermis pilocytic astrocytomas

Background

Pilocytic astrocytomas (PAs) are slow growing neoplasms and usually located at the cerebellum. There has been certainty regarding the truthful benefit of surgical resection for patients with PA. Gross total resection (GTR) of PAs, especially those being situated in deep regions, remains a surgical challenge. Generally, they are considered as benign and usually develop in young patients. PAs, belonging to WHO I can be cured by radical resection. The patients with PA have excellent prognosis if complete resection can be conducted. The use of fluorescein in vermis PA surgery has not been yet reported. Our data presents fluorescein facilitates surgical resection of vermis PA.

Methods

Five milligrams per kilogram of fluorescein sodium was intravenously injected directly before general anesthesia for the three patients with PA. The yellow 560 filter was employed for microsurgical tumor resection. Surgical outcomes were assessed concerning the extent of resection.

Results

Most portion of PA in the three cases was found to be highly fluorescent after intravenous fluorescein sodium injection, which markedly enhanced tumor visibility. Gross total resection in all of the patients was achieved without further neurological deficits. No adverse effects and complications resulting from fluorescein sodium were observed over the postoperative course.

Conclusions

Intraoperative guidance by fluorescein sodium as a new, simple, safe, and practical procedure can enhance the fidelity of tumor tissue and increase the possibility of completely resecting PAs.

Extended Volumetric Follow-up of Juvenile Pilocytic Astrocytomas Treated with Proton Beam Therapy

Purpose

To describe volume changes following proton beam therapy (PBT) for juvenile pilocytic astrocytoma (JPA), we analyzed post-PBT magnetic resonance imaging (MRI) to clarify survivorship, response rate, and the concept of pseudoprogression.

Materials and Methods

Pediatric patients with a histologic diagnosis of JPA after a biopsy or subtotal resection and at least 4 post-PBT MRIs were retrospectively reviewed. After PBT, tumors were contoured on follow-up T1-contrasted MRIs, and 3-dimensional volumes were plotted against time, with thresholds for progressive disease and partial response. Patterns of response, pseudoprogression, and progression were uncovered. Post-PBT clinical course was described by the need for further intervention and survivorship.

Results

Fifteen patients with a median of 10 follow-up MRIs made up this report: 60% were heavily pretreated with multiple lines of chemotherapy, and 67% had undergone subtotal resection. With a median follow-up of 55.3 months after a median of 5400 centigray equivalents PBT, estimates of 5-year overall survival and intervention-free survival were 93% and 72%, respectively. The crude response rate of 73% included pseudoprogressing patients, who comprised 20% of the entire cohort; the phenomenon peaked between 3 and 8 months and resolved by 18 months. One nonresponder expired from progression. Post-PBT intervention was required in 53% of patients, with 1 patient resuming chemotherapy. There were no further resections or radiotherapy. One patient developed acute lymphoblastic leukemia, and another developed biopsy-proven radionecrosis.

Conclusion

The PBT for inoperable/progressive JPA provided 72% 5-year intervention-free survival in heavily pretreated patients. Although most patients responded, 20% demonstrated pseudoprogression. The need for post-PBT surveillance for progression and treatment-induced sequelae should not be underestimated in this extended survivorship cohort.

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.

Rare infundibular tumors: clinical presentation, imaging findings, and the role of endoscopic endonasal surgery in their management

Background The spectrum of infundibular lesions is broad and distinct from sellar pathologies. In many cases, histology is needed to establish the correct diagnosis and determine the treatment approach. Methods Medical files of eight patients with distinct infundibular tumors were reviewed. Histopathologically confirmed diagnosis included three pituicytomas, three granular cell tumors, and two pilocytic astrocytomas. Results Patients shared similar imaging findings and clinical symptoms, including visual impairment (n = 5), hypopituitarism (n = 4), and headache (n = 4); one patient presented with disseminated disease and symptoms from spinal metastases. All the pituicytomas, two granular cell tumors, and one infundibular pilocytic astrocytoma case underwent endoscopic endonasal surgery; gross total resection was achieved in five patients, three developed postoperative diabetes insipidus, and two developed hypopituitarism. No recurrences were observed. One granular cell tumor patient was treated with gamma-knife radiosurgery after stereotactic biopsy; the tumor remained stable in size for over 9 years. The infundibular pilocytic astrocytoma patient who presented with spinal metastases received radiotherapy and systemic chemotherapy. The overall mean follow-up period was 25.1 months. Conclusion Infundibular tumors are rare entities that represent a diagnostic challenge. Histopathological examination is essential for definitive diagnosis. Surgery, radiation therapy, and chemotherapy all have a role in the management of these tumors.

Pilocytic astrocytoma mimicking craniopharyngioma: a case series

Although they are one of the most common brain tumours in childhood, pilocytic astrocytomas are rare in adulthood. We report a series of three pilocytic astrocytomas presenting as an intra/suprasellar mass in the fourth to sixth decades of life. All three radiologically mimicked the appearance of a craniopharyngioma, thus representing a potential radiological and diagnostic pitfall. In this series all three patients underwent successful operative management and have remained well throughout follow-up. The majority of information concerning pilocytic astrocytomas is derived from paediatric populations and so only limited and often conflicting data exist for pilocytic astrocytomas developing in adulthood. Decisions regarding treatment of pilocytic astrocytomas in adults must be made on a multidisciplinary, case-by-case basis.

Pilocytic astrocytoma survival in adults: analysis of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute

Pilocytic astrocytoma is a WHO grade 1 brain tumor common in children. Relatively little is known about the behavior of pilocytic astrocytomas in adult patients, largely due to the rarity of pilocytic astrocytoma in this population. Some data suggest that adults share the excellent prognosis seen in children, while other reports suggest more aggressive tumor behavior in adult patients. Patients diagnosed with pilocytic astrocytoma between 1973 and 2008 were identified in the National Cancer Institute Surveillance, Epidemiology, and End Results Program database. Age-group specific survival was analyzed with overall, expected, and cancer-specific survival rates. Further survival analyses were performed with the Kaplan-Meier method and Cox Proportional Hazards models. 3,066 patients with pilocytic astrocytoma were identified, including 865 patients aged 20 years and older. Survival rates declined significantly with age, from 96.5% 60-month survival in patients 5-19 years (95% CI 95.3-97.4) to 52.9% 60-month survival in adult patients 60+ years of age (95% CI 38.4-65.5), with a corresponding decrease in relative and cancer-specific survival rates. Gross total resection was a positive prognostic indicator in adults, while patients receiving radiation had shorter survival regardless of extent of resection. Pilocytic astrocytoma is associated with higher mortality in adult patients than in children and teens, and survival decreases with increasing age in adults. The morbidity of pilocytic astrocytoma in adults provides rationale for future trials of adjuvant treatment in high-risk patients.

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.

Long-term Follow-up of Pediatric Benign Cerebellar Astrocytomas

BACKGROUND

The long-term prognosis of cerebellar astrocytomas needs to be reviewed.

OBJECTIVE

To elucidate the factors influencing tumor recurrence or progression and to determine how long these patient with cerebellar astrocytomas require surveillance with neuroimaging.

METHODS

A retrospective review of 101 children surgically treated for a cerebellar astrocytoma and followed up for &lt; 10 years was performed.

RESULTS

Mean follow-up was 18.4 years. Total resection confirmed by postoperative imaging was performed in 51 patients (50.5%; group A). Twenty-three patients (22.8%) had surgical total resection; however, equivocal residual tumor was found on postoperative imaging (group B). Subtotal resection leaving a portion of brainstem or cerebellar peduncle was performed in 27 patients (26.7; group C). Of these 50 residual tumors, 16 (32%) showed spontaneous regression and 8 (16%) showed arrested growth. Radiographic recurrence or progression was noted in 29 patients (28.7%). Only 3 of 51 patients (5.9%) of group A with total resection had recurrence, whereas 26 of 50 residual tumors (52%; groups B and C) progressed. The only factor affecting recurrence or progression by multivariate analysis was the extent of surgical resection. All tumor recurrence or progression except for 1 (96.6%) occurred within 8 years from the original surgery (range, 2–132 months).

CONCLUSIONS

Overall prognosis of cerebellar astrocytomas is good; the 10-year survival rate was 100% and recurrence- or progression-free rate was 71.3% in our cohort. Almost half of residual tumors showed spontaneous regression or arrested growth in the long term. Eight to 10 years is considered to be a reasonable follow-up period by neuroimaging.

Postoperative imaging surveillance in pediatric pilocytic astrocytomas

OBJECT

Currently there is no consensus regarding the frequency of neuroimaging following gross-total resection (GTR) of pilocytic astrocytoma (PA) in children. Whereas several reports recommend no postoperative imaging, one study proposed surveillance MR imaging studies to detect delayed recurrences.

METHODS

The records of 40 consecutive pediatric patients who underwent GTR of infratentorial PAs were examined. All had follow-up duration of ≥ 2 years. Patients underwent early (< 48 hours) postoperative MR imaging, followed by surveillance imaging at 3-6 months, 1 year, and variably thereafter. The classification of GTR was based on a lack of nodular enhancement on early postoperative MR imaging. Demographic, clinical, and pathological variables were analyzed with respect to recurrence status. Univariate and multivariate analyses were performed to evaluate the association between pathological variables and recurrence-free survival (RFS).

RESULTS

Of 13 patients demonstrating new nodular enhancement on MR imaging at 3-6 months, the disease progressed in 10, with a median time to recurrence of 6.4 months (range 2-48.2 months). At last follow-up, 29 patients had no recurrence, whereas in 1 additional patient the tumor recurred at 48 months, despite the absence of a new contrast-enhancing nodule at 3-6 months (for a total of 11 patients with recurrence). No demographic variable was associated with recurrence. Nodular enhancement on MR imaging at 3-6 months was significantly associated with recurrence in both univariate (p < 0.0001) and multivariate (p = 0.0015) analyses. Among the pathological variables, a high Ki 67 labeling index (LI) was similarly significantly associated with RFS in both univariate (p = 0.0016) and multivariate (p = 0.034) analyses. Multivariate models that significantly predicted RFS included a risk score incorporating Ki 67 LI and CD68 positivity (p = 0.0022), and a similar risk score combining high Ki 67 LI with the presence of nodular enhancement on initial surveillance MR imaging (p < 0.0001).

CONCLUSIONS

Surveillance MR imaging at 3-6 months after resection predicts tumor recurrence following GTR. One patient suffered delayed recurrence, arguing against a "no imaging" philosophy. The data also highlight the pathological variables that can help categorize patients into groups with high or low risk for recurrence. Larger series are needed to confirm these associations.

Central nervous system tumors

Central nervous system (CNS) tumors comprise 15% to 20% of all malignancies occurring in childhood and adolescence. They may present in a myriad of ways, often delaying diagnosis. Symptoms and signs depend on the growth rate of the tumor, its location in the central nervous system (CNS), and the age of the child. This article describes the presentation, diagnosis and management of these tumors.

Supratentorial pilocytic astrocytomas, astrocytomas, anaplastic astrocytomas and glioblastomas are characterized by a differential expression of S100 proteins

The levels of expression of the S100A1, S100A2, S100A3, S100A4, S100A5, S100A6 and S100B proteins were immunohistochemically assayed and quantitatively determined in a series of 95 astrocytic tumors including 26 World Health Organization (WHO) grade I (pilocytic astrocytomas), 23 WHO grade II (astrocytomas), 25 WHO grade III (anaplastic astrocytomas) and 21 WHO grade IV (glioblastomas) cases. The level of the immunohistochemical expression of the S100 proteins was quantitatively determined in the solid tumor tissue (tumor mass). In addition twenty blood vessel walls and their corresponding perivascular tumor astrocytes were also immunohistochemically assayed for 10 cases chosen at random from each of the four histopathological groups. The data showed modifications in the level of S100A3 protein expression; these modifications clearly identified the pilocytic astrocytomas from WHO grade II-IV astrocytic tumors as a distinct biological group. Modifications in the level of S100A6 protein expression enabled a clear distinction to be made between low (WHO grade I and II) and high (WHO grade III and IV) grade astrocytic tumors. Very significant modifications occurred in the level of S100A1 protein expression (and, to a lesser extent, in their of the S100A4 and S100B proteins) in relation to the increasing levels of malignancy. While the S100A5 protein was significantly expressed in all the astrocytic tumors (but without any significant modifications in the levels of malignancy), the S100A2 protein was never expressed in these tumors. These data thus indicate that several S100 proteins play major biological roles in human astrocytic tumors.

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

INTRODUCTION

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

CASE REPORTS

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

DISCUSSION

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

Neurosurgical treatment of brain tumors in children

Primary brain tumors are the most common solid neoplasms of childhood. The diagnosis of brain tumors in the general pediatric population remains challenging. Nevertheless, it is clear that refinements in imaging, surgical technique, and adjunctive therapies have led to longer survival and an improving quality of life in children with brain tumors.

A population-based study of the incidence and survival rates in patients with pilocytic astrocytoma

OBJECT

The incidence of pilocytic astrocytomas and the rate of patient survival were analyzed in a population-based study in the canton of Zürich, Switzerland.

METHODS

Between 1980 and 1994, 987 astrocytic and oligodendroglial tumors were diagnosed, of which 55 (5.5%) were pilocytic astrocytomas. The incidence rate, adjusted to the World Standard Population, was 4.8 per 1 million per year. The mean age at clinical diagnosis was 19.6 +/- 12.7 years, and the male/female ratio was 1.12. The most frequent tumor sites were the cerebellum (40%), followed by supratentorial locations (35%), the optic pathway and hypothalamus (11%), and the brainstem (9%). The mean follow-up period was 12 years. Observed survival rates were 100% at 5 years and 95.8% at 10 years after diagnosis (relative survival rate at 10 years: 96.8%). Seven patients (13%) received postoperative radiotherapy, but this did not significantly affect survival. In all patients the tumors were histologically classified as WHO Grade I, except in two patients who had anaplastic pilocytic astrocytoma (Grade III), one of whom died after 7 years, whereas the other was still alive after 10 years.

CONCLUSIONS

This population-based study shows that, because of the benign biological behavior of pilocytic astrocytomas and advances in microneurosurgery, the survival rates for patients with these tumors are excellent, regardless of postoperative radiotherapy.

Pilocytic astrocytoma of a spinal nerve root. Case report

A case of pilocytic astrocytoma involving a spinal nerve root is reported. A 39-year-old woman presented with a 1-year history of progressive pain and numbness, predominantly in the S-1 dermatome. Magnetic resonance (MR) imaging revealed an intradural lesion at the tip of the conus medullaris. The intradural tumor was excised as was the sacrificed nerve root. Histological examination showed a pilocytic astrocytoma in which there were unusual features of calcification and ossification. At 3-year follow-up review MR imaging demonstrated no residual tumor. To the best of the authors' knowledge, this is the first case of a primary pilocytic astrocytoma, a tumor typically of central nervous system origin, arising from a spinal nerve root.

Cranial nerve root entry zone primary cerebellopontine angle gliomas: a rare and poorly recognized subset of extraparenchymal tumors

With the exception of patients with neurofibromatosis type II, pediatric extraparenchymal cerebellopontine angle (CPA) tumors of any sort are extremely rare. Most gliomas encountered in the CPA in either children or adults involve the CPA as exophytic extensions of primary brain stem and/or cerebellar tumors. We encountered an unusual case of a giant CPA pilocytic astrocytoma arising from the proximal trigeminal nerve, completely separate from the brain stem. A nine-year-old girl with no evidence for any neurocutaneous syndrome, presented with headaches, mild obstructive hydrocephalus, trigeminal hypesthesia and a subtle peripheral facial paresis. Pre-operative neuroimaging suggested a petroclival meningioma. The tumor was completely resected via a right pre-sigmoid, retro-labyrinthine, subtemporal, transtentorial ('petrosal') approach, using intraoperative neurophysiological monitoring, with minimal morbidity. This appears to be the first reported case of a pediatric primary CPA glioma and the seventh reported case of primary CPA glioma, overall. It represents the second reported case of a primary CPA pilocytic astrocytoma. Given the findings in this case and the six other cases of primary CPA gliomas reported in the literature, as well as the results of histological studies of normal cranial nerves, we hypothesize that the point of origin of these rare and unusual tumors is the root entry zone of the involved cranial nerves. The differential diagnosis of primary CPA tumors should be expanded to include cranial nerve root entry zone primary CPA gliomas.

Benign cerebellar astrocytomas in children

OBJECT

Cerebellar astrocytomas are benign tumors of childhood known to be associated with excellent long-term survival in patients in whom complete surgical resection is possible. However, the roles of other factors--clinical, radiological, histological, and therapeutic--in the survival of the patient, tumor recurrence, and long-term patient outcome remain imprecise. The goal of this study was to examine these factors and their relationships.

METHODS

To clarify these issues a retrospective review was conducted of 168 children who were surgically treated for a cerebellar astrocytoma at Hôpital Necker-Enfants Malades between 1955 and 1995. These patients' clinical files were examined, the histological characteristics of their tumors were reviewed, and their outcomes were assessed according to Bloom's scale and the Wechsler intelligence quotient test. Of the 168 patients in the study, 91 were male and 77 were female with a mean age of 6.9 years and a mean follow up lasting 7.7 years. Tumors were identified as being strictly located in the cerebellum in 76.2% of the patients and as involving the brainstem (referred to as the "transitional form") in 23.8% of the patients. Complete surgical excision was possible in 88.7% of cases. There was a total mortality rate of 4.2% and a tumor recurrence rate of 9.5%. Fifty-eight percent of the patients had no neurological sequelae at follow-up evaluation. Pejorative factors that were discovered by multivariate analysis to be important included: a long preoperative duration of symptoms and the transitional form of tumor with respect to survival; incomplete tumor excision with respect to an increased risk of recurrence; and a long preoperative duration of symptoms, an early epoch during which surgery was performed (1955-1974), severe ventricular dilation, and the transitional form of tumor with respect to a poorer long-term patient outcome.

CONCLUSIONS

The presence of brainstem involvement (tumor in the transitional form) emerged as a significant negative prognostic factor and should be treated as a distinct nosological entity. The extent of surgical excision has a significant bearing on the risk of tumor recurrence.