Medulloblastoma. A report of 201 cases with emphasis on the relationship of histologic variants to survival

Radiotherapy in Medulloblastoma-Evolution of Treatment, Current Concepts and Future Perspectives

Simple Summary

Craniospinal irradiation (CSI) is the backbone of medulloblastoma treatment and the first treatment to achieve a cure in many patients. Within the last decades, significant efforts have been made to enhance efficacy in combination with chemotherapy. With this approach, a majority of low- and standard-risk patients can be cured. In parallel, many clinical trials have dealt with CSI-dose reduction and reduction of boost volume in order to decrease long-term toxicity, particularly neurotoxicity. Within these trials, standardized quality assurance has helped to increase the accuracy of treatment and improve prognosis. More recently, advances of radiotherapy techniques such as proton treatment allowed for better sparing of healthy tissue in order to further diminish detrimental long-term effects. Major future challenges are the adaption of radiotherapy regimens to different molecularly defined disease groups alone or together with new targeted agents. Moreover, and even more importantly, innovative combinatorial treatments are needed in high- and very-high risk situations.

Abstract

Medulloblastoma is the most frequent malignant brain tumor in children. During the last decades, the therapeutic landscape has changed significantly with craniospinal irradiation as the backbone of treatment. Survival times have increased and treatments were stratified according to clinical and later molecular risk factors. In this review, current evidence regarding the efficacy and toxicity of radiotherapy in medulloblastoma is summarized and discussed mainly based on data of controlled trials. Current concepts and future perspectives based on current risk classification are outlined. With the introduction of CSI, medulloblastoma has become a curable disease. Due to combination with chemotherapy, survival rates have increased significantly, allowing for a reduction in radiation dose and a decrease of toxicity in low- and standard-risk patients. Furthermore, modern radiotherapy techniques are able to avoid side effects in a fragile patient population. However, high-risk patients remain with relevant mortality and many patients still suffer from treatment related toxicity. Treatment needs to be continually refined with regard to more efficacious combinatorial treatment in the future.

Prognostic Factors in Adult Medulloblastoma. A Clinico-Pathologic Study

Aims and background.

Medulloblastoma in adults is a rare tumor. The small number of cases in the reported series has not permitted a definite assessment of the prognostic role of clinical, pathologic and cell kinetics factors. The largest series of medulloblastoma in adults treated in a single institution is herein reported.

Methods.

The clinical, therapeutic, pathologic and proliferation features of medulloblastoma in 44 adult patients (> 18 years) were analyzed retrospectively with regard to postoperative survival. The proliferation potential of each tumor was evaluated by the immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67, clone MIB-1, in paraffin sections.

Results.

The overall 5- and 10-year survival rates were 40% and 35.6%, respectively. Significant factors in predicting a longer postoperative survival were: age < 37 years, decade of management (1977-1990), radiotherapy (50-55 Gy on the posterior fossa and 30-35 Gy on the spinal cord) and nuclear isomorphism. When corrected for adequacy of radiotreatment, desmoplastic type and differentiation were significantly correlated with a shorter survival. The PCNA-labelling index (LI) ranged from 34.5 to 82.2%, the MIB-1-LI ranged from 9.6 to 64.7%. No association was found between PCNA- or MIB-1-LI values and microscopic features, or between LI values and prognosis.

Conclusions.

Contrary to a general assumption, desmoplastic medulloblastoma and differentiated medulloblastoma are negative prognostic factors in adequately radiotreated adult patients. This may possibly be referred to lower radiosensitivity of these tumor variants. The LI with PCNA or Ki-67 is of no help in identifying aggressive tumors.

Clinical Outcomes Among Children With Standard-Risk Medulloblastoma Treated With Proton and Photon Radiation Therapy: A Comparison of Disease Control and Overall Survival

PURPOSE

The purpose of this study was to compare long-term disease control and overall survival between children treated with proton and photon radiation therapy (RT) for standard-risk medulloblastoma.

METHODS AND MATERIALS

This multi-institution cohort study includes 88 children treated with chemotherapy and proton (n=45) or photon (n=43) RT between 2000 and 2009. Overall survival (OS), recurrence-free survival (RFS), and patterns of failure were compared between the 2 cohorts.

RESULTS

Median (range) age was 6 years old at diagnosis (3-21 years) for proton patients versus 8 years (3-19 years) for photon patients (P=.011). Cohorts were similar with respect to sex, histology, extent of surgical resection, craniospinal irradiation (CSI) RT dose, total RT dose, whether the RT boost was delivered to the posterior fossa (PF) or tumor bed (TB), time from surgery to RT start, or total duration of RT. RT consisted of a median (range) CSI dose of 23.4 Gy (18-27 Gy) and a boost of 30.6 Gy (27-37.8 Gy). Median follow-up time is 6.2 years (95% confidence interval [CI]: 5.1-6.6 years) for proton patients versus 7.0 years (95% CI: 5.8-8.9 years) for photon patients. There was no significant difference in RFS or OS between patients treated with proton versus photon RT; 6-year RFS was 78.8% versus 76.5% (P=.948) and 6-year OS was 82.0% versus 87.6%, respectively (P=.285). On multivariate analysis, there was a trend for longer RFS with females (P=.058) and higher CSI dose (P=.096) and for longer OS with females (P=.093). Patterns of failure were similar between the 2 cohorts (P=.908).

CONCLUSIONS

Disease control with proton and photon radiation therapy appears equivalent for standard risk medulloblastoma.

[Evolution of the management of pediatric and adult medulloblastoma]

Medulloblastoma are cerebellar tumours belonging to the group of primitive neuroectodermal tumours (PNET) and are the most common malignant brain tumours of childhood. These tumours are rare and heterogeneous, requiring some multicentric prospective studies and multidisciplinary care. The classical therapeutic approaches are based on clinical, radiological and surgical data. They involve surgery, radiation therapy and chemotherapy. Some histological features were added to characterize risk. More recently, molecular knowledge has allowed to devise risk-adapted strategies and helped to define groups with good outcome and reduce long-term sequelae, improve the prognostic of high-risk medulloblastoma and develop new therapeutic tools.

Medulloblastoma: recurrence and metastasis

Medulloblastoma is the most common malignant brain tumor of childhood. Although there is now long-term survival or cure for the majority of children, the survivors bear a significant burden of complications due, at least in part, to the intense therapies given to ensure eradication of the tumor. Significant efforts have been made over the years to be able to distinguish between patients who do and do not need intensive therapies. This review summarizes the history and current state of clinical risk stratification, pathologic diagnosis and genetics. Recent developments in correlation between genetics and pathology, genome-wide association studies and the biology of medulloblastoma metastasis are discussed in detail. The current state of clinical treatment trials are reviewed and placed into the perspective of potential novel therapies in the near term.

Medulloblastoma: A common pediatric tumor: Prognostic factors and predictors of outcome

BACKGROUND

Medulloblastoma is a common malignancy in the pediatric population, accounting for 25% of all childhood brain tumors and relatively uncommon in adults. This review was to investigate treatment outcome and prognostic factors after treatment of medulloblastoma.

MATERIALS AND METHODS

A total of 53 patients with histological confirmed medulloblastoma cases treated at our institute between 2006 and 2012 were included in the study. Demographic variables, clinical variables, radiological findings and treatment details with respect to age, sex, signs and symptoms, location of tumor, extent of surgical resection, histopathology type, radiotherapy dose, follow-up period and outcomes were recorded. Survival was analyzed by using these parameters.

RESULTS

Thirty-one (58.5%) patients were pediatric (<14 years), and 22 (41.5%) patients were adults (≥14 years). Duration of symptoms were <3 months in 19 (36%) and more than 3 months in 34 (64%) patients. Tumor resection was performed in all patients with gross total resection in 8 (15%) patients, near total resection in 34 (64%) patients and subtotal resection in 11 (21%) patients. All patients underwent postoperative craniospinal irradiation (CSI) delivering a median craniospinal dose of 36 Gy with additional boosts to the posterior fossa up to 54 Gy. Median overall survival was 50 months for the total group whereas 36 months for pediatric age group and 70 months for adult group. Desmoplastic histology showed an improved outcome compared with other histologies with a median survival of 71 months compared with that of classical medulloblastoma histology being 36 months and other histologies shown a median survival of 34 only.

CONCLUSIONS

Treatment of medulloblastoma with surgery and CSI yields long survival rates in both children and adults. Adult age group and desmoplastic histology were associated with a favorable outcome.

Extra-axial medulloblastoma in the cerebellar hemisphere

Extra-axial medulloblastoma is a rare phenomenon. We report a case in a 5-year-old boy who presented with nausea, vomiting, and gait disturbance. He was treated with total removal of the tumor. This is the first case of an extra-axially located medulloblastoma occurring in the cerebellar hemisphere posteriolateral to the cerebellopontine angle in Korea. Although the extra-axial occurrence of medulloblastoma is rare, it should be considered in the differential diagnosis of extra-axial lesions of the posterior fossa in children.

Neuronal differentiation associated with Gli3 expression predicts favorable outcome for patients with medulloblastoma

Medulloblastoma (MB) is a malignant cerebellar tumor arising in children, and its ontogenesis is regulated by Sonic Hedgehog (Shh) signaling. No data are available regarding the correlation between expression of Gli3, a protein lying downstream of Shh, and neuronal differentiation of MB cells, or the prognostic significance of these features. We re-evaluated the histopathological features of surgical specimens of MB taken from 32 patients, and defined 15 of them as MB with neuronal differentiation (ND), three as MB with both glial and neuronal differentiation (GD), and 14 as differentiation-free (DF) MB. Gli3-immunoreactivity (IR) was evident as a clear circular stain outlining the nuclei of the tumor cells. The difference in the frequency of IR between the ND+GD (94.4%) and DF (0%) groups was significant (P < 0.001). The tumor cells with ND showed IR for both Gli3 and neuronal nuclei. Ultrastructurally, Gli3-IR was observed at the nuclear membrane. The overall survival and event-free survival rates of the patients in the ND group were significantly higher than those in the other groups. The expression profile of Gli3 is of considerable significance, and the association of ND with this feature may be prognostically favorable in patients with MB.

Medulloblastoma in the first year of life: A report of five cases

Five infants with cerebellar medulloblastoma, who all presented within the first year of life, are presented. The initial characteristic presenting symptoms included vomiting and macrocrania, frequently followed by a delay in normal development. No patients showed any signs or symptoms of cerebellar dysfunction. One infant, who was initially diagnosed as having a congenital hydrocephalus, died 4 months after undergoing a cerebrospinal fluid shunt operation, while the remaining four patients all underwent direct surgery for their tumors and three also received an additional course of postoperative radiation therapy. Of these four patients, three died within 4 years after diagnosis, with a mean survival period of 2.7 years, whereas one is still alive after a follow-up period of more than 20 years. However, the patient does suffer from both physical and intellectual handicaps. The clinical and histological features of infantile medulloblastomas are reviewed while the therapeutic problems associated with these tumors are also discussed.

CRABP-II methylation: a critical determinant of retinoic acid resistance of medulloblastoma cells

Medulloblastoma cells exhibit varied responses to therapy by all-trans retinoic acid (RA). The underlying mechanism for such diverse effects however remains largely unclear. In this study, we attempted to elucidate the molecular basis of RA resistance through the study of RA signaling components in both RA-sensitive (Med-3) and RA-resistant (UW228-2 and UW228-3) medulloblastoma cells. The results revealed that RARα/β/γ and RXRα/β/γ were found in the three cell lines. Expression of CRABP-I and CRABP-II was seen in Med-3 cells, up-regulated when treated with RA, but was absent in UW228-2 and UW228-3 cells regardless of RA treatment. Bisulfite sequencing revealed 8 methylated CG sites at the promoter region of CRABP-II in UW228-2 and UW228-3 but not in Med-3 cells. Demethylation by 5-aza-2'-deoxycytidine recovered CRABP-II expression. Upon restoration of CRABP-II expression, both UW228-2 and UW228-3 cells responded to RA treatment by forming neuronal-like differentiation, synaptophysin expression, β-III tubulin upregulation, and apoptosis. Furthermore, CRABP-II specific siRNA reduced RA sensitivity in Med-3 cells. Tissue microarray-based immunohistochemical staining showed variable CRABP-II expression patterns among 104 medulloblastoma cases, ranging from negative (42.3%), partly positive (14.4%) to positive (43.3%). CRABP-II expression was positively correlated with synaptophysin (rs = 0.317; p = 0.001) but not with CRABP-I expression (p > 0.05). In conclusion, aberrant methylation in CRABP-II reduces the expression of CRABP-II that in turn confers RA resistance in medulloblastoma cells. Determination of CRABP-II expression or methylation status may enable a personalized RA therapy in patients with medulloblastomas and other types of cancers.

Outcome and prognostic factors of desmoplastic medulloblastoma treated within a multidisciplinary treatment concept

Background

Desmoplasia in medulloblastoma is often diagnosed in adult patients and was repeatedly associated with improved results. Today, all medulloblastoma patients receive intensive multimodal treatment including surgery, radiotherapy and chemotherapy. This study was set up to investigate treatment outcome and prognostic factors after radiation therapy in patients with desmoplastic medulloblastomas.

Methods

Twenty patients treated for desmoplastic medulloblastoma in the Department of Radiation Oncology at the University of Heidelberg between 1984 and 2007 were included. Data were collected retrospectively. Tumor resection was performed in all patients. All patients underwent postsurgical radiotherapy (RT). Two patients underwent whole brain radiotherapy (WBRT), and 18 patients received craniospinal irradiation (CSI). In all patients, an additional boost was delivered to the posterior fossa. The median dose to the whole brain and the craniospinal axis was 35.2 Gray (Gy), and 54.4 Gy to the posterior fossa. Fourteen patients received chemotherapy, including seven who were treated with combined radiochemotherapy and twelve who received adjuvant chemotherapy. Statistical analysis was performed using the log-rank test and the Kaplan-Meier method.

Results

Median follow-up was 59 months. Overall (OS), local (LPFS) and distant progression-free survival (DPFS) was 80%, 71.2%, and 83.3% at 60 months. Patients who suffered from local or distant relapses had significantly worse outcome. Five patients died from recurrent medulloblastoma. Treatment-associated toxicity was acceptable.

Conclusions

Multimodal approaches with surgical resection followed by chemoirradiation achieved high response rates with long OS in desmoplastic medulloblastoma patients. Staging parameters expected to predict for poor prognosis did not significantly influence outcome. However, success of any first line regimen had strong impact on disease control, and remission was achieved in no patient with relapsing disease. Multimodal concepts must be evaluated in further clinical trials.

Prognostic factors after extraneural metastasis of medulloblastoma

PURPOSE

To review the existing literature regarding the characteristics, prognostic factors, treatment, and survival of patients with medulloblastoma, who develop extraneural metastasis (ENM).

METHODS AND MATERIALS

A PubMed search of English language articles from 1961 to 2007 was performed, yielding 47 articles reporting on 119 patients. Factors analyzed included age, time interval to development of ENM, ENM location, central nervous system (CNS) involvement, treatment, and outcome.

RESULTS

Sites of ENM included bone in 84% of patients, bone marrow in 27% of patients, lymph nodes in 15% of patients, lung in 6% of patients, and liver in 6% of patients. Median survival was 8 months after diagnosis of ENM. The 1-, 2-, and 5-year overall survival (OS) rates after diagnosis of ENM were 41.9%, 31.0%, and 26.0%, respectively. The 1-, 2-, and 5-year progression-free survival (PFS) rates after diagnosis of ENM were 34.5%, 23.2%, and 13.4%, respectively. For patients without CNS involvement at the time of ENM diagnosis, the 1-, 2-, and 5-year OS rates for those treated with and without radiotherapy (RT) were 82.4%, 64.8%, and 64.8% vs. 51.0%, 36.6%, and 30.5%, respectively (p = 0.03, log-rank test). RT did not significantly improve OS or PFS rates for those with CNS involvement. Concurrent CNS involvement, ENM in the lung or liver, a time interval of <18 months to development of ENM, and a patient age of <16 years at ENM diagnosis were found to be negative prognostic factors for both OS and PFS.

CONCLUSIONS

Several prognostic factors were identified for patients with ENM from medulloblastoma. Patients without concurrent CNS involvement, who received RT after ENM diagnosis had an OS and PFS benefit compared to those who did not receive RT.

Survival and prognostic factors in a series of adults with medulloblastomas

OBJECT

In this article, the authors report their experience in the management of adult patients with medulloblastoma at their institution to identify prognostic factors important for survival and disease control.

METHODS

Between 1977 and 2005, 27 patients who were >or=16 years old and had medulloblastoma were treated consecutively. There were 16 women and 11 men with a median age of 21 years (range 16-54 years). Gross-total resection was performed in 21 patients, subtotal (>or=90%) in 2, incomplete in 1, and biopsy in 3 patients. Six patients had the desmoplastic variant, and 21 patients presented with classic medulloblastoma. Staging according to the Chang classification showed 4 patients with tumors invading the brainstem (2 with Stage T3b and 2 with Stage T4), 3 patients with metastases (2 with Stage M2 and 1 with Stage M3), and 1 patient in whom the stage was unknown (Stage MX) who died 10 days postoperatively. Twenty patients were assigned to the standard-risk group and 7 to the high-risk group. All patients except the one whose status was classified as Stage MX underwent craniospinal radiotherapy at our institution. Seven patients received chemotherapy before radiotherapy.

RESULTS

The 5- and 10-year overall survival rates for the present study were 81 and 62%, respectively. The median overall survival time was 17.7 years. The 5- and 10-year event-free survival rates were 72 and 57%, respectively. The median event-free survival time was 17.9 years. Univariate analysis showed that survival was significantly correlated with sex (women had a better prognosis than men) and M stage (patients without metastases had a better outcome). Patient age, duration of symptoms, Karnofsky Performance Scale score at presentation, hydrocephalus, tumor location, brainstem invasion, extent of resection, histological subtype, preradiotherapy chemotherapy, risk group, and period of presentation were not significant variables. Multivariate analysis identified sex and M stage as well as the period of presentation as independent prognostic factors for overall and event-free survival times. Eleven patients suffered tumor recurrence within a median time of 4.2 years. The posterior fossa was not the most common site of recurrence, and delayed recurrence was not rare. All patients in whom the tumor recurred have died despite aggressive treatments. The median survival time after diagnosis of recurrence was 2.5 years. Questionnaires on quality of life and cognition showed high scores in favor of limited negative effects in the perception of mental and physical health after treatment. The authors observed 1 supposed second malignancy (thyroid carcinoma) and no evidence of pituitary dysfunction.

CONCLUSIONS

Long-term survival is possible in adults treated for medulloblastoma. Although rare, metastasis seeding at presentation is a poor prognostic factor. The possibility of delayed recurrence necessitates close follow-up of all patients. Tumor recurrences should be treated with aggressive therapies as some patients may have sustained response. Adjuvant chemotherapy should be given to high-risk patients, but its role in reducing recurrences, particularly distant ones, remains unclear in the standard-risk group.

Histologic features and prognosis in pediatric medulloblastoma

Because individual histologic features in childhood medulloblastoma alter survival likelihood, the recent 4th edition of the World Health Organization (WHO) Classification of Brain Tumors recognizes desmoplastic/nodular medulloblastoma, medulloblastoma with extensive nodularity, large cell medulloblastoma, and anaplastic medulloblastoma, in addition to medulloblastoma with no other distinguishing features. To identify features affecting survival likelihood, we investigated 33 histologic features in 556 childhood tumors diagnosed as medulloblastoma in the Childhood Brain Tumor Consortium (CBTC) database; all features have CBTC verified read-reread reliability and those features important in the classification of medulloblastoma and its WHO variants regardless of their measured reliability. Nineteen features had no effect on survival likelihood, and 8 features were too prevalent or too rare to measure their effect on survival. Nodules, balls, high cell density, and fine fibrillary stroma improved survival likelihood; necrosis and prominent nucleoli worsened survival likelihood. Of note, the presence of desmoplasia, currently a defining feature (along with nodules) for desmoplastic/nodular medulloblastoma, had no effect on survival likelihood. We conclude that the presence of nodularity in medulloblastoma is important to improved survival likelihood, particularly when combined with balls and fine fibrillary stroma. Given the "overlap" of desmoplastic/nodular medulloblastoma and nodular medulloblastoma, we suggest they be combined into a diagnosis of nodular medulloblastoma, with nodules, balls, and fine fibrillary stroma as defining criteria. We also suggest that because of the considerable overlap of anaplastic medulloblastoma and large cell medulloblastoma they be combined into 1 diagnosis of anaplastic/large cell medulloblastoma, with necrosis and prominent nucleoli among the defining criteria.

Molecular pathogenesis of adult brain tumors and the role of stem cells

Primary brain tumors consist of neoplasms with varied molecular defects, morphologic phenotypes, and clinical outcomes. The genetic and signaling abnormalities involved in tumor initiation and progression of the most prevalent adult primary brain tumors, including gliomas, meningiomas, and medulloblastomas, are described in this article. The current understanding of the cell-of-origin of these neoplasms is reviewed, which suggests that the malignant phenotype is propelled by cells with stem-like qualities. A comprehensive understanding of the molecular basis of transformation and the cell-of-origin of these neoplasms will enable the formulation of more targeted treatment alternatives that could improve survival and quality of life.

Nodule formation and desmoplasia in medulloblastomas-defining the nodular/desmoplastic variant and its biological behavior

Among the variants of medulloblastoma in the current WHO classification of nervous system tumors, the desmoplastic variant, which has been reported to constitute 5%-25% of pediatric medulloblastomas, is defined by its nodular collections of neurocytic cells bounded by desmoplastic internodular zones. We have studied the frequency, morphological features and biological behavior of medulloblastomas in two contemporaneous SIOP/UKCCSG trial cohorts of children with medulloblastomas, CNS9102 (n = 315) and CNS9204 (n = 35), focusing on tumors with nodular and desmoplastic phenotypes. In children aged 3-16 years (CNS9102), the nodular/desmoplastic medulloblastoma represented 5% of all tumors, while in infants aged <3 years (CNS9204) this variant represented 57% of medulloblastomas. Using iFISH to detect molecular cytogenetic abnormalities in medulloblastomas with a nodular architecture, we demonstrated distinct genetic profiles in desmoplastic and non-desmoplastic (classic and anaplastic) tumors; in particular, abnormalities of chromosome 17 occurred in the latter, but not the former. Significantly different outcomes were demonstrated for classic, nodular/desmoplastic and large cell/anaplastic medulloblastomas in both cohorts. In conclusion, the nodular/desmoplastic medulloblastoma appears to have clinical, genetic and biological characteristics that set it apart from other variants of this tumor.

Histopathologic grading of adult medulloblastomas

BACKGROUND

Histopathologic evaluation of the degree and extent of anaplasia is a useful prognostic parameter in pediatric medulloblastomas. Whether the same applies to adult medulloblastomas is not known.

METHODS

The study included 74 adult patients with histologically confirmed medulloblastomas and retrospectively reassessed 67 cases with available slides for the presence of nodularity, collagen deposition (desmoplasia without nodules), and degree and extent of anaplasia.

RESULTS

Patients included 43 men and 31 women with the following age distribution: 18-40 years (84%); 41-50 years (9%); and 51-70 years (7%). At last follow-up, 56 patients were alive with a mean follow-up of 6.3 years (range, 0.1-20.8 years). A variety of treatments were employed during the study period, including postoperative radiation (85%) and chemotherapy (27%). Precise treatment modalities were unknown in 12% of patients. Anaplasia was absent (34%), mild (34%), moderate (27%), or severe (5%). Severe anaplasia was diffuse in 2 cases and focal in 1, although in the latter cases severe anaplasia was diffusely present at the time of disease recurrence. Male sex was associated with decreased 10-year recurrence-free survival (40% vs 66%; P = .021) and overall survival (38% vs 68%; P = .005). Severe anaplasia at first resection was found to be an independent predictor of decreased recurrence-free survival (P = .005) and overall survival (P = .015).

CONCLUSIONS

The incidence of severe anaplasia in adult medulloblastomas is lower than in the pediatric population. Male sex and the presence of severe anaplasia at the time of first resection are predictors of decreased recurrence-free and overall survival. However, the significance of severe anaplasia should be regarded with caution based on the small number of tumors with this feature in the current study.

Multifocal desmoplastic medulloblastoma in an african-american child with nevoid basal cell carcinoma (gorlin) syndrome. Case report

The authors present the case of a 2.5-year-old African-American boy with desmoplastic medulloblastoma (MB) and nevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, an autosomal dominant disorder resulting from mutations in the patched (PTCH) gene that predisposes to neoplasias (including basal cell carcinomas [BCCs] and MB) and to widespread congenital malformations. The diagnosis of NBCCS was suspected based on the clinical examination, patient and family medical histories, and histopathological characteristics of the tumor. Radiotherapy was withheld. The diagnosis of NBCCS was confirmed by DNA testing, which revealed a novel mutation in the PTCH gene. This is the first report of an African-American child with MB diagnosed with NBCCS prior to radiotherapy. Although only a small number of patients with MB have NBCCS, the diagnosis must be considered because radiotherapy in such patients can lead to the formation of BCCs and other intracranial neoplasms within the irradiated field. This case emphasizes the importance of obtaining thorough family and patient medical histories and of carefully examining the patient and close relatives for signs of NBCCS to avoid the potentially devastating consequences of missing this diagnosis.

Medulloblastoma: therapy and biologic considerations

Tremendous strides have been made in both the treatment and the biologic understanding of medulloblastoma. Present optimal treatment can cure most medulloblastoma patients. A substantial minority of patients, however, will have recurrent or progressive disease. Recent studies have demonstrated that the success of treatment is not simply a matter of chance, but rather can be predicted based on specific biologic markers. These markers predict outcome independent of clinical staging and make clear that medulloblastomas are a biologically diverse group of tumors with variable clinical behavior. Molecular biologic investigation, including replication of tumorigenesis in transgenic mice, has further elucidated the complex biology of medulloblastoma. Current standard and investigational treatments, however, do not yet make use of biologic markers that predict risk of recurrence. Practical limitations have slowed the pace at which treatment paradigms can be revised to incorporate biologic insights. Mouse medulloblastoma models may provide an important bridge between biologic investigation and the development of new therapeutic approaches.

Anaplasia and grading in medulloblastomas

The variable clinical outcomes of medulloblastoma patients have prompted a search for markers with which to tailor therapies to individuals. In this review, we discuss clinical, histological and molecular features that can be used in such treatment customization, focusing on how histopathological grading can impact both patient care and research on the molecular basis of CNS embryonal tumors. Medulloblastomas span a histological spectrum ending in overtly malignant large cell/anaplastic lesions characterized by increased nuclear size, marked cytological anaplasia, and increased mitotic and apoptotic rates. These "high-grade" lesions make up approximately one quarter of medulloblastomas, and recur and metastasize more frequently than tumors lacking anaplasia. We believe anaplastic change represents a type of malignant progression common to many medulloblastoma subtypes and to other CNS embryonal lesions as well. Correlation of these histological changes with the accumulation of genetic events suggests a model for the histological and molecular progression of medulloblastoma.

Recent advances in embryonal tumours of the central nervous system

INTRODUCTION

Embryonal tumours of the central nervous system (CNS) are the commonest malignant paediatric brain tumours. This group includes medulloblastomas, supratentorial primitive neuroectodermal tumours, atypical teratoid/rhabdoid tumours, ependymoblastomas, and medulloepitheliomas. Earlier, all these tumours were grouped under a broad category of primitive neuroectodermal tumours (PNETs). However, the current WHO classification (2000) separates them into individual types based on significant progress in the understanding of their distinctive clinical, pathological, molecular genetic, histogenetic, and behavioural characteristics. Furthermore, advances in histopathology and molecular genetics have shown great promise for refining risk assessment in these tumours, especially medulloblastomas, thus providing a more accurate basis for tailoring therapies to individual patients. Correlation of histological changes with genetic events has also led to a new model of medulloblastoma tumorigenesis.

REVIEW

This review presents an updated comparative profile of these tumours, highlighting the clinical and biological relevance of the recent advances.

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.

Immunohistochemical analysis for histopathological subtypes in pediatric medulloblastomas

Medulloblastomas occurring in children represent a histological spectrum of varying anaplasia and nodularity. In order to determine whether immunohistochemical markers might be useful parameters in subclassifying these tumors, 17 pediatric medulloblastomas, including nine diffuse/non-anaplastic, four diffuse/anaplastic, three nodular/non-anaplastic and one nodular/anaplastic subtypes, were studied. In the present report, we investigate the expression of neural cell adhesion molecule (NCAM), nerve growth factor receptor (NGFR), neurofilament (NF), synaptophysin (SYN), glial fibrillary acidic protein (GFAP), S100, Bcl-2, and Ki-67 by using the immunohistochemistry against specific antibodies. This study showed that NGFR, NF, GFAP and S100 were not detected in anaplastic subtypes of medulloblastomas (0/5), while non-anaplastic subtypes were mainly expressed within the nodules. All 17 tumors were reactive for NCAM, SYN and Bcl-2. In addition, Ki-67 labeling indices for anaplastic subtypes (39.0 +/- 7.42%) were significantly higher than that of non-anaplastic medulloblastomas (11.4 +/- 8.04%; P < 0.0001). These results suggest that immunohistochemical markers are a useful adjunct in characterizing subtypes of pediatric medulloblastomas.

Medulloblastomas with favorable versus unfavorable histology: how many small blue cell tumor types are there in the brain?

Prognostically favorable and unfavorable variants of medulloblastoma have recently been identified, corresponding to medulloblastoma with extensive nodularity and large cell/anaplastic medulloblastoma, respectively. In an effort to identify clinically relevant grading criteria for medulloblastoma in general, 330 Pediatric Oncology Group (POG) cases were carefully reviewed for presence and extent of histologic anaplasia, nodularity, and desmoplasia. The resulting data was statistically analyzed using event-free and overall patient survival as endpoints. Significant anaplasia (moderate to severe) was identified in 24% of cases and was strongly associated with decreased survival times. Additionally, those with diffuse or extensive anaplasia fared worse than those with only focal anaplasia. Although the study confirmed the favorable prognosis for the rare cases of medulloblastoma with extensive nodularity, lesser degrees of nodularity or desmoplasia were not associated with a statistically significant survival advantage. Medulloblastoma grading based on anaplasia demonstrated a statistically stronger association with patient outcome than clinical staging. Therefore, histologic grading of medulloblastomas seems warranted as a routine diagnostic aid.

Classifying the medulloblastoma: insights from morphology and molecular genetics

Significant advances in the treatment of the medulloblastoma (MB) have been made in the last 30 years, reducing mortality by 2-fold. Further improvements in the cure rate require an increased understanding of the biology of MBs, and this will translate into refinements in their classification. Scrutiny of the cytological variation found among MBs has recently led to the concept of the anaplastic MB, which overlaps the large-cell variant and appears to share its poor prognosis. In contrast, the MB with extensive nodularity, a distinctive nodular/desmoplastic variant occurring in infants, has a better outcome than most MBs in these young patients. Building on cytogenetic studies that have drawn attention to abnormalities on chromosome 17 in over a third of MBs, research shows non-random losses on chromosomes 8, 9, 10, 11 and 16, and gains on chromosomes 1, 7 and 9. Overexpression of ErbB2 receptors and losses on chromosome 17p have been proposed as independent indicators of aggressive behaviour, while high TrkC receptor expression indicates a favourable outcome. There is a strong association between anaplastic/large-cell tumours and MYC amplification, which has previously been linked with aggressive disease, but associations between abnormalities on chromosome 17 and anaplastic/large-cell MBs and between abnormalities in the shh/PTCH pathway and the desmoplastic variant are more controversial. Classification of the MB histopathologically and according to profiles of molecular abnormalities will help both to rationalize approaches to therapy, increasing the cure rate and reducing long-term side-effects, and to suggest novel treatments.

Are childhood and adult medulloblastomas different? A comparative study of clinicopathological features, proliferation index and apoptotic index

Childhood medulloblastomas have been suspected to be biologically different from adult tumors, though comparative studies are sparse in the literature. The present study aims to establish any differences or nexus in the biological characteristics between childhood and adult medulloblastomas. A total of 181 medulloblastomas were studied with respect to clinical and histological characteristics, MIB-1 labeling index (MIB-1 LI), apoptotic index (AI), ratio of apoptotic to LI, p53 and Bcl-2 protein expressions. Two-thirds (112) of the 181 medulloblastomas occurred in children (< or = 15 years) and 69 in adults (> 15 years). Childhood tumors were more commonly of classical histology and midline location while the desmoplastic variant and lateral location occurred more frequently in adults. Adult medulloblastomas were biologically less aggressive, having lower growth rate parameters (mean MIB-1 LI 19.1 +/- 15.7; AI 3.73 +/- 2.71 and AI:LI 0.207 +/- 0.162) as compared to childhood tumors (mean MIB-1 LI 28.3 +/- 20.4; AI 2.86 +/- 2.14 and AI:LI 0.108 +/- 0.111). p53 and Bcl-2 protein expressions were infrequent in all groups of tumors. No difference was noted in any of the parameters when classical and desmoplastic medulloblastomas were compared as a whole. But when compared between the age groups, an interesting observation (hitherto unreported in English literature) was that both classical and desmoplastic variants of childhood medulloblastomas had higher LI, lower AI and lower AI:LI ratio than their counterparts in adults, indicating that differences in growth rates cannot be attributed to differences in the frequency of occurrence of the histological variants in the two age groups. Thus, this study conclusively shows that there is a biological difference between childhood and adult medulloblastomas which is independent of standard histology and appeared to be associated more with age-related factors. This also warrants less-aggressive therapy for adult medulloblastoma.

Familial medulloblastoma: case report of one family and review of the literature

OBJECTIVE AND IMPORTANCE

Medulloblastoma is the most common malignant brain tumor and the most common malignant solid tumor in children. Most medulloblastomas are sporadic, but rare familial forms have been described. To the best of our knowledge, only 10 case reports of familial medulloblastoma have been published. A variety of candidate genes have been suggested to be involved in familial medulloblastomas. However, the exact pathogenesis and genetics involved in familial medulloblastoma remain unknown.

CLINICAL PRESENTATION

We describe the presentation of medulloblastoma in two siblings (one of each sex) and their great-uncle. The three cases differ with regard to age at onset and pathological subtype of medulloblastoma. INTERVENTION OR TECHNIQUE: Immunostaining of tissue blocks for gene products involved in medulloblastoma differed in the two siblings for beta-catenin and was similar with staining for gli.

CONCLUSION

This article is only the second report in the literature to address the genetics of familial medulloblastoma in the absence of characterized conditions such as Li-Fraumeni's cancer syndrome and basal cell nevus, Rubinstein-Taybi's, and Turcot's syndromes. The discrepancy in beta-catenin staining in the two siblings suggests that the two tumors differentiated through divergent pathways. We briefly summarize all published cases of familial medulloblastoma and review the literature on the genes involved in medulloblastoma formation.

Histopathologic grading of medulloblastomas: a Pediatric Oncology Group study

BACKGROUND

Medulloblastomas are small cell embryonal tumors of the cerebellum found predominantly in children, only slightly more than half of whom survive. Predicting favorable outcome has been difficult, and improved stratification clearly is required to avoid both undertreatment and overtreatment. Patients currently are staged clinically, but no pathologic staging system is in use. Two rare subtypes at extreme ends of the histologic spectrum, i.e., medulloblastomas with extensive nodularity and large cell/anaplastic medulloblastomas, are associated with better and worse clinical outcomes, respectively. However, there is little data about correlations between histologic features and clinical outcome for most patients with medulloblastomas that fall between these histologic extremes of nodularity and anaplasia. Therefore, the authors evaluated the clinical effects of increasing anaplasia and nodularity in a large group of children with medulloblastomas, hypothesizing that increasing nodularity would predict better clinical outcomes and that increasing anaplasia would presage less favorable results.

METHODS

Medulloblastomas from 330 Pediatric Oncology Group patients were evaluated histologically with respect to extent of nodularity, presence of desmoplasia, grade of anaplasia, and extent of anaplasia. Pathologic and clinical data were then compared using Kaplan-Meier and log-rank analyses.

RESULTS

Increasing grade of anaplasia and extent of anaplasia were associated strongly with progressively worse clinical outcomes (P < 0.0001 for both). Significant anaplasia (moderate or severe) was identified in 24% of medulloblastoma specimens. Neither increasing degrees of nodularity nor desmoplasia were associated significantly with longer survival.

CONCLUSIONS

Moderate anaplasia and severe anaplasia were associated with aggressive clinical behavior in patients with medulloblastomas and were detected in a significant number of specimens (24%). Pathologic grading of medulloblastomas with respect to anaplasia may be of clinical utility.

Primitive neuroectodermal tumors of the brainstem: investigation of seven cases

OBJECTIVE

We discuss the clinical aspects, pathology, and molecular genetics of 7 patients with primitive neuroectodermal tumors (PNETs) arising in the brainstem that were treated at our institution from 1986 through 1995. Most neuro-oncologists avoid performing biopsies in children with pontine tumors. This article raises the question as to whether biopsies should be performed, because treatment recommendations might differ if a PNET was diagnosed rather than a pontine glioma.

PATIENTS AND METHODS

We reviewed the clinical neuro-oncology database and the files of the Division of Neuropathology at New York University Medical Center from 1986 through 1995 and identified 7 histologically confirmed PNETs arising in the brainstem among 146 pediatric brainstem tumors. The clinical, neuroradiological, and neuropathological data were reviewed. Postmortem examinations were performed in 2 cases. Formalin-fixed, paraffin-embedded tumor tissues were also available in 6 of 7 patients that were tested for p53 gene mutations using single-strand conformation polymorphism analysis. We also tested 9 cerebellar PNETs, 9 brainstem gliomas, and 3 normal brains for p53 gene mutations as controls.

RESULTS

All 7 patients presented with focal cranial nerve deficits, and 2 were also hemiparetic. The median age at diagnosis was 2.7 (1-8 years). Magnetic resonance imaging (MRI) characteristics included a focal intrinsic exophytic nonenhancing brainstem lesion that had low T1-weighted and high T2-weighted signals. Hydrocephalus was present in 5 patients at diagnosis, 3 of whom had leptomeningeal dissemination. Meningeal dissemination occurred later in the course of the disease in 3 other patients. Five children required shunts at diagnosis and another 2 at recurrence. Despite therapy, all 7 PNET patients died within 17 months of diagnosis with a mean survival of 8 (4-17) months. No mutation in the p53 gene was detected.

CONCLUSIONS

Brainstem PNETs tend to arise at a younger age than brainstem gliomas and medulloblastomas. The MRI pattern suggests a localized rather than a diffuse intrinsic nonenhancing brainstem tumor. Like other PNETs, brainstem PNETs have a high predilection to disseminate within the central nervous system. The absence of p53 mutations is similar to other PNETs. Despite their origin close to the cerebellum, brainstem PNETs exhibit a more aggressive behavior and result in worse clinical outcomes than do cerebellar PNETs.

Adult medulloblastoma: prognostic factors and patterns of relapse

OBJECTIVE

To determine the patterns of relapse and the prognostic factors for adult medulloblastomas treated in the magnetic resonance imaging era.

METHODS

Between 1986 and 1996, 32 adult patients (age, > or =16 yr) with medulloblastomas confined to the craniospinal axis were treated in our institutions. Twenty cases involved classic histological features and 12 involved the desmoplastic variant. The Chang staging distribution was as follows: T1, 2; T2, 17; T3, 10; T4, 3; M0, 24; M1, 1; M2, 4; M3, 3. Brainstem invasion was present in nine patients. Lesions were midline in 13 cases and lateral in 19. Resection was complete in 17 cases, subtotal in 6, and partial in 5, with biopsy only in 4 cases. All patients received postoperative radiotherapy, with median doses of 36 Gy to the entire craniospinal axis and 55 Gy to the posterior fossa. Twenty-four patients received chemotherapy (20 before radiotherapy, 3 after radiotherapy, and 1 before and after radiotherapy).

RESULTS

With a median follow-up period of 5.4 years, 17 patients experienced recurrences. At 5 and 8 years, overall survival rates were 83 and 45% and disease-free survival rates were 57 and 40%, respectively. The 5- and 8-year posterior fossa control rates were 67 and 59%, respectively. Twenty-nine percent of all relapses occurred more than 5 years after treatment. The posterior fossa was the most common site of relapses. In univariate analyses, factors adversely affecting posterior fossa control were less than complete resection (P<0.001), the presence of brainstem invasion (P = 0.02), and the use of chemotherapy (P = 0.03). The overall radiotherapy duration was marginally significant in predicting posterior fossa control, with 5-year posterior fossa control rates of 81 and 49% for durations of less than 48 days and 48 days or more, respectively (P = 0.06). In a multivariate analysis, complete resection was predictive of improved posterior fossa control (P = 0.02) and disease-free survival (P = 0.02) rates. Of the eight low-risk patients who received radiotherapy alone, three experienced recurrences in the bone as the only site of relapse.

CONCLUSION

Late relapse is common among adult patients with medulloblastomas, and long-term follow-up monitoring is important. Because of the high risk of systemic failure among the low-risk patients treated with radiotherapy alone, the role of chemotherapy for this group of patients needs to be further investigated. Complete resection, the absence of brainstem invasion, and an overall radiotherapy duration of less than 48 days are important prognostic factors.

[Medulloblastoma in adults: analysis of a casuistics and surgical results]

We report on 15 cases of medulloblastoma of adult onset (8 male and 7 female) operated upon posterior fossa approach from February 1988 to October 1995. Tumors were localized in cerebellar hemisphere in 7 cases (one with extension to supratentorial notch and another case reaching the cerebello-pontine angle cistern), in vermis and hemisphere in four, only in vermis in another four. Resection was total in seven patients, subtotal in other seven, and partial in one. There was no operative mortality. Aspects regarding biological behavior, diagnosis, pathological findings, surgery and survival are discussed as well as prognostic factors.

Prognostic value of tumor-associated antigens immunoreactivity and apoptosis in medulloblastomas. An analysis of 73 cases

Medulloblastomas (MB) are the most common central nervous system malignancies in children. Numerous publications describe efforts to identify the predictive value of various patterns of MB pathology and immunohistochemistry, but received data appear to be controversial. Seventy-three patients with cerebellar MB were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to various tumor-associated antigens. Also, apoptosis detection by the in situ end-labeling method was performed. Survival analysis was made using univariate and multivariate models. Tenascin immunoreactivity and apoptotic index (AI) > or = 1.5% were found to be closely associated with poor prognosis according to an univariate analysis (P = 0.008 and 0.003, respectively). The multivariate Cox proportional hazard model exhibited independent prognostic value for the apoptotic rate only (P = 0.023). Tumors with tenascin expression and AI > or = 1.5% significantly prevailed among MB with metastatic dissemination, whereas expression of c-erbB2 oncoprotein and epidermal growth factor receptor was found to be more typical for cases with local tumor recurrence. We came to the conclusion that tenascin immunoreactivity and AI were useful for individual MB prognosis.

Diagnostic markers in paediatric medulloblastoma: a Paediatric Oncology Group Study

AIMS

We have reviewed immunohistochemically 17 paediatric medulloblastomas in order to determine if correlations exist that might be useful in subclassifying these tumours.

METHODS AND RESULTS

The patient group included 11 children who had died (mean survival 13 months) and six still alive (followed for up to 10 years). Ten tumours were diffuse and six were nodular (one biopsy had only perivascular tumour). Of the 10 diffuse tumours, three were desmoplastic: of the six nodular tumours, all six were desmoplastic. All 17 tumours were synaptophysin-reactive: three nodular tumours were glial fibrillary acidic protein (GFAP)-reactive in the nodules (two of three S 100-reactive tumours were also GFAP-reactive). MIB-1 labelling indices (LI) ranged from 5 to 80%. Six tumours exhibited at least 1% LI against Tp53 (Mab D07 and/or Mab 1801). Eight cases were 100% bcl2-reactive with nine cases having an LI <80% ('low labelling'). All nine 'low labelling' bcl2 cases were TP53 non-reactive; all six Tp53-reactive cases were bcl2 100% reactive. Six of 10 patients with diffuse medulloblastomas survived 18 months or less while four of 10 are alive up to 10 years. In contrast, five of six patients with nodular neoplasms died within 48 months of diagnosis with one patient followed up for less than 1 year.

CONCLUSIONS

Immunohistochemistry is a useful adjunct in characterizing subsets of paediatric medulloblastomas and confirms that larger co-operative studies may be fruitful in identifying a prognostic utility of a combined histochemical/immunohistochemical analysis on these tumours.

Medulloblastoma: time-dose relationship based on a 30-year review

PURPOSE

Time-dose relationships have proven important in many cancer sites. This study evaluates the time factors involved in the successful postoperative radiotherapy of medulloblastoma, based on a 30-year experience in a single institution.

METHODS AND MATERIALS

Fifty-three patients with medulloblastoma received postoperative craniospinal radiotherapy with curative intent between 1963 and 1993. Seven patients (13%) underwent biopsy alone, 28 patients (53%) had subtotal excision, and 18 patients (34%) had gross total excision. Eleven patients received adjuvant chemotherapy. The mean posterior fossa dose was 53.1 Gy; most patients received 54.0 Gy (range, 34.3 to 69.6 Gy). For 41 patients receiving once-a-day therapy, the mean dose was 50.6 Gy (range, 34.3 to 56.0 Gy). For 12 patients receiving twice-a-day therapy, the mean dose was 61.8 Gy (range, 52.6 to 69.6 Gy). Minimum follow-up was 2 years, and median follow-up was 10.7 years. Survival, freedom from relapse, and disease control in the posterior fossa were calculated using the Kaplan-Meier method, and multivariate analysis was performed for prognostic factors. Variables related to radiotherapy were examined, including dose to the craniospinal axis, dose to the posterior fossa, fractionation (once-a-day vs. twice-a-day), use of adjuvant chemotherapy, risk group [high (> or =T3b or > or =M1) or low (< or =T3a and M0-MX)], interval between surgery and radiotherapy (excluding patients receiving chemotherapy before radiotherapy), and duration of radiotherapy.

RESULTS

At 5 and 10 years, overall survival rates were 68 and 64%, respectively, and freedom-from-relapse rates were 61 and 52%, respectively. Rates of disease control in the posterior fossa at 5 and 10 years were 79 and 68%, respectively. At 5 years, absolute survival rates after biopsy alone, subtotal excision, and gross total excision were 43, 67, and 78%, respectively (p=0.04), and posterior fossa control rates were 27, 89, and 83%, respectively (p=0.004). Duration of the treatment course was the only radiotherapy-related variable with a significant impact on freedom from relapse and posterior fossa control. For patients whose radiation treatment duration was < or =45 days, posterior fossa control was 89% at 5 years, compared with 68% for those treated for >45 days (p=0.01). Duration of treatment also affected freedom from relapse at 5 years: < or =45 days (76%) compared with >45 days (43%), p=0.004.

CONCLUSION

Our study demonstrates that if adequate doses are used, then radiotherapy treatment duration will significantly affect the outcome in terms of control of disease in the posterior fossa and freedom from relapse. Fractions of at least 1.75 Gy given once a day, or a twice-a-day regimen should yield optimal local control results.

Medulloblastoma: survival and late recurrence after the Collins' risk period

Sixty-three patients with cerebellar medulloblastoma were treated between 1963 and 1992 at our institution. Among them, 10 patients have survived beyond the Collins' risk period. These included 6 males and 4 females who ranged in age from 6 months to 12 years at the time of diagnosis. A total removal of the tumor was achieved in 4 patients, while there was a subtotal removal in 3, and a partial removal in 3. Histologically, 6 tumors were classified as a classical type of medulloblastoma, and 4 were diagnosed as being a desmoplastic type. Postoperatively, 9 patients received craniospinal radiation therapy, and one received local radiation to the primary site. During the follow-up period of 3.9-25.4 years, 5 patients have been in continuous remission for from 14.2 to 25.4 years and are leading normal lives, 2 have survived for 18.1 and 18.5 years with mild to moderate neurological deficits, while the remaining 3 died after the Collins' risk period. Two out of these last 3 patients were under the age of one year at the time of onset, while the remaining one died after a second recurrence. We conclude that careful follow-up is needed for all long-term survivors even after the Collins' risk period, especially for those who were under the age of 1 year at onset and who failed in the initial treatments.

Is medulloblastoma the same tumor in children and adults?

The appearance of medulloblastoma in adult age and the uncertain overlapping of prognostic factors in pediatric and adult populations stimulate the question of whether medulloblastoma is different in adults and in children. The pathologic features, proliferation potential and glial/neuronal differentiation have been investigated in 42 adult medulloblastomas and 42 medulloblastomas of children; the quantitative data have been compared between the two groups of age. Homer-Wright rosettes, nuclear polymorphism and histologic signs of neuronal differentiation were more frequent in children cases; GFAP-positive tumor cells and desmoplastic type were more frequent in adult cases. The mean, median and rage of Lis, with PCNA and MIB-1 were significantly (p < 0.05) higher in adults than in children. All cases, independently from age of the patients were immunoreactive with markers of neuronal commitment (class III beta tubulin isotype, MAP-2, neurofilaments). The immunoreactivity pattern suggested a more mature neuronal character in desmoplastic cases of adults than of children and in classic cases of children than of adults. In conclusion, some phenotypic differences between childhood and adult medulloblastoma exist, but do not support a substantially different course of the disease. The higher proliferation potential in adult than in childhood cases is unexpected in a tumor of embryonal origin, and reduces the applicability of Collin's law to medulloblastoma.

[Medulloblastoma in adults. Val-de-Grace hospital experience (1975-1994) and literature review]

PURPOSE

Retrospective analysis of prognostic factors in a series of 14 adult patients presenting with medulloblastoma treated by surgery and subsequent radiotherapy.

PATIENTS AND METHODS

Thirteen male and one female patients (mean age, 27 years; range 20-40) presenting with medulloblastoma were treated at the Val-de-Grâce hospital from 1975 to 1994. The mean delay between the initial symptoms and the diagnosis was 17 weeks (range, 2-76). The tumor was median in three cases, lateral in seven, and median and lateral in four. Eleven medulloblastomas belonged to the classical subtype and three others to the desmoplastic type. Patients were treated by surgery followed by external radiation therapy. The ablation was complete in four cases and incomplete in ten cases.

RESULTS AND CONCLUSION

Five- and ten-year overall survival rates were 63 and 25%, respectively. There was a trend toward a higher probability of survival for older patients (ie, for patients above 26 years of age) presenting with a desmoplastic central tumor treated by complete surgery and subsequent post-operative radiotherapy. Results are discussed in regard to the literature.

Cytogenetics of pediatric central nervous system tumors

A cytogenetic analysis was performed on short-term cultures of 43 previously untreated childhood central nervous system neoplasms of various histology. The cells were obtained from pediatric patients, none of whom had received therapy before karyotypic evaluation. Successful chromosome studies were performed on 24 tumors. The most commonly detected structural abnormalities involved chromosomes 1 and 17. Other structural chromosome abnormalities involved chromosomes 3, 6, 8, 9, 11, 12, and 20.

Surgical management of medulloblastoma

Recent technological aids and understanding of pathophysiology has made the surgery of medulloblastoma safer. The guiding principle for the neurosurgeon remains removal of bulky disease, but there is no justification for removal of small amounts of tumor from critical locations. Post-operative complications include hydrocephalus, hematoma, mutism, asceptic meningitis, gastroinstestinal hemorrhage, and cervical instability. Staging is best done preoperatively with MRI, and presence of dissemination remains the most important prognostic factor in this disease. Postoperative surveillance imaging is of questionable value.

Medullocytoma (lipidized medulloblastoma). A cerebellar neoplasm of adults with favorable prognosis

This study describes three cases of neuroectodermal cerebellar neoplasms occurring in adults, characterized by a monomorphic population of round cells with scanty cytoplasm and focal areas of lipid accumulation. Astrocytic and neuronal differentiation was confirmed in these cells by glial fibrillary acidic protein and synaptophysin immunoreactivity. Electron microscopy performed in two cases showed neuritic processes, synapses, and dense-core granules. Patients included two men and one woman, and the age at diagnosis was 36, 37, and 57 years, respectively. Two patients refused any postoperative treatment. One of these had two surgically removed recurrences after 10 and 11 years and died postoperatively from intracranial hemorrhage. The second had two recurrences after 10 and 15 years and is alive and in good health at the last follow-up. The third patient received postoperative radiotherapy and is alive and well after 2 years. Review of the literature revealed seven cases of cerebellar neoplasms with histological features similar to those observed in our series. These lesions have been considered a variant of medulloblastomas. The age of patients ranged from 42 to 77 years (mean age, 51 years); four were women, 3 men. Follow-up information available in two cases indicates a 5-year survival with surgery alone. These data indicate that these cerebellar neuroectodermal neoplasms have morphologically unique features and indolent biologic behavior that distinguish them from the highly aggressive medulloblastoma; the term medullocytoma for this form is suggested.

Medulloblastoma in adults

PURPOSE

To assess the outcome and prognostic factors for adult patients with medulloblastoma managed by postoperative radiotherapy between 1958 and 1988 at the Princess Margaret Hospital.

METHODS AND MATERIALS

A retrospective review was undertaken of 48 patients age 16 years or older who received radiotherapy for medulloblastoma. The median age at diagnosis was 25 years, with 36 male and 12 female patients. Sixteen tumors were confined to midline structures, and 32 were localized to a cerebellar hemisphere or involved midline and lateral structures. The desmoplastic variant was reported in 12 cases. Complete macroscopic removal was achieved in 22 patients, subtotal removal in 23, and biopsy only in 3. Forty-six patients received craniospinal radiation and 2 patients received local irradiation only.

RESULTS

Median overall survival was 7.9 years, and 5- and 10-year overall survival was 62% and 41%, respectively. Significant factors for disease-free survival were M stage (M0 vs. M1-4, p = 0.0005), functional state at the time of radiotherapy (1-2 vs. 3-5, p = 0.005), and the absence or presence of hydrocephalus preoperatively (p = 0.02). Twenty-four patients developed recurrent disease, with 14 relapsing first in the posterior fossa. Subtotal removal of tumor (p = 0.04) was the only factor predictive of posterior fossa relapse.

CONCLUSIONS

Patients with disease outside the posterior fossa at diagnosis, symptomatic patients (neurologic functional state 3-5) at the time of radiotherapy, and those who present with hydrocephalus have poorer disease-free survival. Gross total resection improved posterior fossa control.