Medulloblastoma in children and in adults: a comparative study

Using diffusion MRI to understand white matter damage and the link between brain microstructure and cognitive deficits in paediatric medulloblastoma patients

PURPOSE

Survivors of medulloblastoma face a range of challenges after treatment, involving behavioural, cognitive, language and motor skills. Post-treatment outcomes are associated with structural changes within the brain resulting from both the tumour and the treatment. Diffusion magnetic resonance imaging (MRI) has been used to investigate the microstructure of the brain. In this review, we aim to summarise the literature on diffusion MRI in patients treated for medulloblastoma and discuss future directions on how diffusion imaging can be used to improve patient quality.

METHOD

This review summarises the current literature on medulloblastoma in children, focusing on the impact of both the tumour and its treatment on brain microstructure. We review studies where diffusion MRI has been correlated with either treatment characteristics or cognitive outcomes. We discuss the role diffusion MRI has taken in understanding the relationship between microstructural damage and cognitive and behavioural deficits.

RESULTS

We identified 35 studies that analysed diffusion MRI changes in patients treated for medulloblastoma. The majority of these studies found significant group differences in measures of brain microstructure between patients and controls, and some of these studies showed associations between microstructure and neurocognitive outcomes, which could be influenced by patient characteristics (e.g. age), treatment, radiation dose and treatment type.

CONCLUSIONS

In future, studies would benefit from being able to separate microstructural white matter damage caused by the tumour, tumour-related complications and treatment. Additionally, advanced diffusion modelling methods can be explored to understand and describe microstructural changes to white matter.

Molecular testing for adolescent and young adult central nervous system tumors: A Canadian guideline

The 2021 World Health Organization (WHO) classification of CNS tumors incorporates molecular signatures with histology and has highlighted differences across pediatric vs adult-type CNS tumors. However, adolescent and young adults (AYA; aged 15–39), can suffer from tumors across this spectrum and is a recognized orphan population that requires multidisciplinary, specialized care, and often through a transition phase. To advocate for a uniform testing strategy in AYAs, pediatric and adult specialists from neuro-oncology, radiation oncology, neuropathology, and neurosurgery helped develop this review and testing framework through the Canadian AYA Neuro-Oncology Consortium. We propose a comprehensive approach to molecular testing in this unique population, based on the recent tumor classification and within the clinical framework of the provincial health care systems in Canada.

Embryonal Tumors of the Central Nervous System: From the Radiologic Pathology Archives

Embryonal tumors of the central nervous system (CNS) are highly malignant undifferentiated or poorly differentiated tumors of neuroepithelial origin and have been defined as a category in the World Health Organization (WHO) classification since the first edition of the "Blue Book" in 1979. This category has evolved over time to reflect our ever-improving understanding of tumor biology and behavior. With the most recent update in 2016, many previous histologic diagnoses incorporate molecular parameters for the first time (genetically defined entities). While medulloblastoma and atypical teratoid/rhabdoid tumor are familiar carryovers from the 2007 CNS WHO classification, there are major changes to the embryonal tumor category: for example, elimination of the term CNS primitive neuroectodermal tumor and addition of a new genetically defined entity, embryonal tumor with multilayered rosettes, C19MC-altered. The purpose of this article is to discuss both the radiologic-pathologic features of CNS embryonal tumors and the new molecularly defined types/subtypes that will become the standard classification/terminology for future diagnoses and tumor research.

Comparing children and adults with medulloblastoma: a SEER based analysis

Medulloblastoma (MB) is a brain malignancy, which commonly occurs in children, but is rare in adults. The Surveillance, Epidemiology, and End Results (SEER) database was used to compare survival, clinical features, and prognostic factors of children and adults with MB from 1992 to 2013. Overall survival estimates were compared using the Kaplan-Meier method, and Cox Proportion Hazard Regression modeling was used to evaluate prognostic variables. We identified 616 children (63.8%) and 349 adults (36.2%) with diagnosis of MB. The estimated survival rates for children diagnosed with MB for 2, 5, and 10 years were 85.6%, 75.5%, and 67.9%, respectively; the corresponding estimates for adults were 84.9%, 74.2%, and 67.3%. Radiotherapy was the only identical prognostic factor observed in the two groups. Children MB patients were more likely to experience distal metastases that was associated with increased hazard of mortality, and be diagnosed after 2003. Among adult MB patients, gross total resection (GTR) was a favorable prognostic factor, while large cell/anaplastic (LC/A) histology was correlated with decreased survival. Our analysis highlighted that both groups had similar overall survival time, but the prognostic factors were not comparable, except radiotherapy which was associated with better survival.

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.

Human corticotrophin releasing factor inhibits cell proliferation and promotes apoptosis through upregulation of tumor protein p53 in human glioma

Corticotropin-releasing factor (CRF) and its receptors have been detected in numerous tumors and have an important role in tumorigenesis and proliferation. However, the role of these peptides has not been established in human glioma and malignant glioma cell lines. The present study evaluated for the first time, the expression of CRF receptor 1 (CRFR1) in 35 human glioma samples, 13 normal brain tissues and human U87 glioma cells using immunohistochemistry, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. Levels of CRFR1 were identified to be significantly increased in human glioma and U87 cells and higher levels of CRFR1 were observed in glioma tissues of higher grade. The biological functions of human CRF (hCRF) on U87 cells glioma cells were investigated by cell counting, a bromodeoxyuridine assay and flow cytometry. The U87 cells under hCRF treatment exhibited reduced proliferation, increased apoptosis and a cell cycle arrest in S and G2/M phase. The tumor protein p53 (p53) gene may participate in the activation of hCRF via CRFR1 in U87 cells, therefore p53 mRNA and protein were evaluated using RT-qPCR and western blot analysis. Finally, the present results suggest that hCRF inhibits proliferation and induces cell-cycle arrest and apoptosis in U87 cells via the CRFR1-mediated p53 signaling pathway. Therefore, the present study also suggests that hCRF may be used therapeutically, and CRFR1 may be a putative therapeutic target for human glioma.

Cerebellopontine angle medulloblastoma with extensive nodularity in a child: case report and review of the literature

BACKGROUND

Cerebellar medulloblastomas (MBs) are one of the most common posterior fossa tumors in children but rarely occur in the cerebellopontine angle (CPA). Only 39 cases of CPA MBs were reported in the literature, and most of them were classic and desmoplastic MBs.

CASE PRESENTATION

A 22-month-old girl presented with progressive cerebellar ataxia. Magnetic resonance imaging showed a large tumor in the right CPA and obstructive hydrocephalus. Surgical resection was performed and achieved total tumor removal. Microscopic examination and immunohistochemical staining revealed the diagnosis of MB with extensive nodularity. The patient recovered from her symptoms during follow-up and was transferred for adjuvant chemotherapy.

CONCLUSION

MB should be considered as a differential diagnosis of a lesion in the CPA. The treatment and outcome of CPA MBs are similar to cerebellar MBs.

Pediatric brain tumors

Among all causes of death in children from solid tumors, pediatric brain tumors are the most common. This article includes an overview of a subset of infratentorial and supratentorial tumors with a focus on tumor imaging features and molecular advances and treatments of these tumors. Key to understanding the imaging features of brain tumors is a firm grasp of other disease processes that can mimic tumor on imaging. We also review imaging features of a common subset of tumor mimics.

Patterns of Failure Following Multimodal Treatment for Medulloblastoma: Long-Term Follow-up Results at a Single Institution

Purpose

The purpose of this study is to investigate the long-term results and appropriateness of radiation therapy (RT) for medulloblastoma (MB) at a single institution.

Materials and Methods

We analyzed the clinical outcomes of 106 patients with MB who received RT between January 1992 and October 2009. The median age was 7 years (range, 0 to 50 years), and the proportion of M0, M1, M2, and M3 stages was 60.4%, 8.5%, 4.7%, and 22.6%, respectively. The median total craniospinal irradiation (CSI) and posterior fossa tumor bed dose in 102 patients (96.2%) treated with CSI was 36 Gy and 54 Gy, respectively.

Results

The median follow-up period in survivors was 132 months (range, 31 to 248 months). A gradual improvement in survival outcomes was observed, with 5-year overall survival rates of 61.5% in 1990s increasing to 73.6% in 2000s. A total of 29 recurrences (27.4%) developed at the following sites: five (17.2%) in the tumor bed; five (17.2%) in the posterior fossa other than the tumor bed; nine (31%) in the supratentorium; and six (20.7%) in the spinal subarachnoid space only. The four remaining patients showed multiple site recurrences. Among 12 supratentorial recurrences, five cases recurred in the subfrontal areas. Although the frequency of posterior fossa/tumor bed recurrences was significantly high among patients treated with subtotal resection, other site (other intracranial/spinal) recurrences were more common among patients treated with gross tumor removal (p=0.016). There was no case of spinal subarachnoid space relapse from desmoplastic/extensive nodular histological subtypes.

Conclusion

Long-term follow-up results and patterns of failure confirmed the importance of optimal RT dose and field arrangement. More tailored multimodal strategies and proper CSI technique may be the cornerstones for improving treatment outcomes in MB patients.

Preponderance of sonic hedgehog pathway activation characterizes adult medulloblastoma

Medulloblastoma (MB) represents approximately 4% of adult brain tumours, and as such is a poorly studied disease. Although many adult MB are treated using paediatric MB protocols, the reported outcomes are inferior to those observed in children. It remains unclear whether biologic differences underlie these clinical observations. We investigated the molecular characteristics of 31 adult MB. Twelve and 19 adult MB were respectively examined using Affymetrix-HG-U133-plus-2.0-genechips and immunohistochemical analyses. 26/31 (84%) of adult MB examined by gene expression and/or immunohistochemical analysis showed evidence of sonic hedgehog (SHH) pathway activation. A comparison of adult and paediatric MB showed that most adult tumours cluster within the SHH-active subgroup of paediatric MB. The preponderance of SHH activity in adult MB tumours was also shown by positive SFRP1 immunostaining in 16/19 adult paraffin-embedded adult MB tumour blocks. A smaller proportion of adult tumours exhibited evidence of WNT pathway activation, as confirmed by nuclear β-catenin staining (9.7%; 3/31). Notably, we found PTCH1 gene mutation in 4/8 samples tested. Similar to children, adult MB has abnormalities in developmental signalling pathways including SHH and WNT. Importantly, we found a preponderance of SHH pathway activation amongst MB tumours in adults. This SHH signature does not appear to correlate with a long-term favourable outcome. Differences in molecular profiles exist between adult and paediatric SHH-driven MB and further investigations are needed to better characterize age-related molecular profiles in this subgroup.

Sudden death due to medulloblastoma

Intracranial tumours can be accompanied with intracerebral and intracerebellar non-traumatic haemorrhage; in some cases, this might be their first clinical sign. We report a case of a man who suffered sudden death due to medulloblastoma, with intratumoral haemorrhage; his tumour had a hemispheric cerebellar positioning. The cerebral oedema seen at autopsy reflected the immediate cessation of cerebral vascular circulation, leading to sudden death. Acute obstructive hydrocephaly is a mechanism widely known in the literature for causing sudden death.

Characteristics and outcomes of medulloblastoma in adults

BACKGROUND

Adult medulloblastoma is a rare disease for which there is no internationally accepted standard of care. Treatment regimens have typically been modeled after pediatric protocols. We sought to review the presentation, management, and outcome of patients with adult medulloblastoma treated at the McGill University teaching hospitals over the past 18 years.

METHODS

Medical records were reviewed to gather demographic and clinical data including presenting symptoms, tumor characteristics, management, survival, and treatment toxicity.

RESULTS

Twenty-five patients were identified. Eleven patients were female and 14 were male. The median age at diagnosis was 30 (range 17-48). Our 5- and 10-year overall survival (OS) rates were 78% and 30%, respectively. Median OS was 108 months and median progression-free survival time was 63 months. Age, sex, risk, stage, extent of resection, chemotherapy and time between surgery and adjuvant therapy did not significantly influence survival outcomes. The most frequently reported adverse events included sensory neuropathy, nausea, vomiting, febrile neutropenia, and radiation dermatitis.

CONCLUSION

Adult medulloblastoma has distinct characteristics from the pediatric population including presentation in the lateral cerebellar hemispheres. Late relapses, especially in the posterior fossa, are a significant problem. Further follow-up will be required to ascertain the effect of adjuvant chemotherapy on survival.

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.

3 Tesla MR Study of Cerebellar Medulloblastoma

Medulloblastoma belongs to the group of highly malignant neuroepithelial tumours and is the commonest tumour in childhood (average age nine years) followed by astrocytoma 1. Medulloblastoma usually arises in the posterior fossa, namely the cerebellar vermis, and more seldom in the fourth ventricle, supratentorium and spinal cord. We describe the 3 Tesla magnetic resonance (MR) features of a medulloblastoma located in the right cerebellar hemisphere adhering to the tentorium in a 16-year-old male.

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.

Surgical outcomes of cerebellar tumors in children

Cerebellar tumors in childhood are generally associated with a favorable outcome if they are managed appropriately. 27 cases of pediatric cerebellar tumors, operated over a 7-year period, are presented. Histopathological diagnoses were as follows: pilocytic astrocytoma (48.2%); medulloblastoma (22.2%); ependymoma (18.5%); fibrillary astrocytoma grade III (3.7%); cystic oligodendroglioma (3.7%), and hemangioblastoma (3.7%). Microscopic gross total resection was achieved in 16 (59.3%) of 27 cases. The total removal of pediatric cerebellar tumors without neurological deficit is possible with appropriate microsurgical techniques excluding brain stem invasion. The follow-up periods must be shorter if brain stem invasion exists. Radiotherapy and chemotherapy are the adjuvant therapies according to the pathological diagnosis and the patient's age.

Medulloblastoma of the cerebellopontine angle--case report

A 21-year-old male patient presented with a rare cerebellopontine angle medulloblastoma manifesting as cerebellar and long tract involvement signs and symptoms. The clinical and radiological characteristics of the lesion were similar to extraaxial lesions of cerebellopontine angle. The histological diagnosis of the lesion was medulloblastoma. Surgery achieved partial removal and was followed by radiotherapy and chemotherapy. The patient remained well after 18 months. Medulloblastoma of the cerebellopontine angle is a relatively rare clinical entity and may occur as a dural-based extraaxial mass.

From the archives of the AFIP: medulloblastoma: a comprehensive review with radiologic-pathologic correlation

Medulloblastoma is the most common pediatric central nervous system malignancy and the most common primary tumor of the posterior fossa in children. This highly malignant neoplasm occurs more frequently in males and usually before 10 years of age. Clinical symptoms and signs are generally brief, typically less than 3 months in duration, and reflect the strong predilection of this tumor to arise within the cerebellum, most often in the vermis. Although much less common, the disease may also occur in adults, usually in the 3rd and 4th decades of life. Surgical resection, radiation therapy, and chemotherapy have substantially lowered the mortality associated with this tumor, with 5-year survival rates now commonly well above 50%. Still, both dissemination at the time of diagnosis and recurrence remain obstacles in achieving a cure. The tumor has characteristic hyperattenuation on unenhanced computed tomographic scans that reflects the high nuclear-cytoplasmic ratio seen at histologic analysis. The tumor typically appears heterogeneous on images, findings that are related to cyst formation, hemorrhage, and calcification and that are even more pronounced with magnetic resonance (MR) imaging. Evidence of leptomeningeal metastatic spread is present in 33% of all cases at the time of diagnosis and is well evaluated with contrast-enhanced MR imaging of the brain and the spine. Although controversial, postoperative surveillance with MR imaging is performed at most institutions in the hope of facilitating a better outcome. With continued research, treatment of these common neoplasms should improve, perhaps even achieving a cure in the future.

Adult cerebellar medulloblastoma: CT and MRI findings in eight cases

Medulloblastoma is a brain tumor of neuroepithelial origin, which represents 15 to 30% of all pediatric brain tumors, and less than 1% of CNS adult neoplasms. We report the imaging findings of 8 adult patients with medulloblastoma. The mean age was 35 years, ranging from 20 to 65 years, and the male:female rate was 3:5. The tumors were predominantly lateral (63%), hyperdense on CT scans (83%), and on the MRI, hypointense on T1 (100%) and hyperintense on T2 (80%) weighted images. It was seen intratumoral necrosis and cysts in six cases and calcifications in three. Hydrocephalus was observed in 5 cases and brain stem invasion in four. The imaging findings of medulloblastomas in adults are different of those in child, and also nonspecific. Although these tumors are uncommon in adults, they must be considered in the differential diagnosis of cerebellar masses in the posterior fossa of this age group.

Glioneuronal tumors of the central nervous system

Advances in the immunohistochemical detection of neuron-specific and neuronal-associated antigens have resulted in the discovery of neuronal elements in certain primary human brain tumors. The results have been not only to expand what neuropathologists commonly recognize as gangliogliomas, including the tumors now known as glioneurocytic tumor with neuropil rosettes and papillary ganglioneuroma, but also to expand the spectrum of tumor types to now include tumors such as central neurocytoma, dysembryoplastic neuroepithelial tumor, and desmoplastic infantile ganglioglioma. These discoveries have helped us to better understand the biology of these tumors and to refine our classification of them. Distinctions among these tumors include sites of predilection, such as the temporal lobe with the dysembryoplastic neuroepithelial tumors, and a spectrum of clinical aggressiveness that spans indolent "quasi-hamartomatous" lesions, such as the dysembryoplastic neuroepithelial tumor, to high-grade, highly aggressive tumors, such as the supratentorial primitive neuroectodermal tumor (World Health Organization Grade IV). Many of these tumors also commonly exhibit a glial component, as determined by both their histologic appearance and their immunoreactivity for glial fibrillary acidic protein. This review covers these recently described lesions, including the desmoplastic infantile ganglioglioma, the dysembryoplastic neuroepithelial tumor, the papillary glioneuronal tumor, the glioneuronal tumor with neuropil rosettes, and the mixed glioblastoma-cerebral neuroblastoma (supratentorial primitive neuroectodermal tumor), as well as the known tumors, ganglioglioma, medulloepithelioma, and medulloblastoma. For pathologists confronted by this growing array of tumors and subtypes, it is appropriate to focus on them and understand the differential diagnosis to be considered when confronted by them.

Adult primitive neuroectodermal tumor: proton MR spectroscopic findings with possible application for differential diagnosis

PURPOSE

To assess the utility of proton magnetic resonance (MR) spectroscopy in the clinical categorization of primitive neuroectodermal tumors (PNETs) in adults.

MATERIALS AND METHODS

In vivo proton MR spectroscopy was performed with an echo time of 136 msec in nine adults with PNET, and findings were retrospectively compared with spectroscopic findings of 22 meningiomas, 12 low-grade astrocytomas, eight anaplastic astrocytomas, 23 glioblastomas, and 21 metastases. Nine resonances were semiquantitatively evaluated. Statistical analysis was performed by using Kruskal-Wallis and Mann-Whitney U tests. The Hochberg correction was applied for multiple comparisons. Results were prospectively validated in 24 tumors of the six types included in the study.

RESULTS

The resonances of choice for identifying PNET were alanine (P <.001) and glutamate and glutamine (P =.004), both decreased with respect to meningioma; choline increased with respect to low-grade (P <.001) and anaplastic astrocytoma (P =.055); and lipids at 1.30 ppm decreased and choline and other trimethyl-amine-containing compounds increased with respect to glioblastoma (P <.001 and P =.004, respectively) and metastasis (P <.001 and P =.021, respectively). We developed an algorithm for bilateral differential diagnosis between PNET and other tumor types. The leave-one-out method was used to test the five possible differential situations in the retrospective data set, with the following results: PNET versus meningioma, 31/23/5/3 (number of total/correct/unclassifiable/incorrect procedures); PNET versus low-grade astrocytoma, 21/19/2/0; PNET versus anaplastic astrocytoma, 17/6/9/2; PNET versus glioblastoma, 32/28/2/2; and PNET versus metastasis, 30/27/1/2. In total, 131 consecutive procedures produced 103 (79%) correct classifications and nine (7%) misclassifications. Twenty-five (78%) of 32 possible procedures in the prospective independent test set produced correct classifications and four (13%) produced incorrect classifications.

CONCLUSION

In vivo proton MR spectroscopy provides useful information in clinical differentiation between PNETs and common brain tumors in adults.

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.

Magnetic resonance imaging of pediatric brain tumors: state of the art

Over the past 25 years, magnetic resonance imaging (MRI) has developed into the primary imaging tool for evaluation of the central nervous system. MRI is the essential imaging study in the twenty-first century for the evaluation of the child with a brain tumor for initial preoperative diagnosis, treatment planning and image-guided therapies. This article provides an overview of the locations and MRI features of common pediatric tumors of childhood.

Etoposide-carboplatin association as 'emergency' up-front chemotherapy in a case of life-threatening adult medulloblastoma

Medulloblastoma is a rare tumor in the adult population. Current therapies include surgery and irradiation. Unlike in children, chemotherapy is not commonly used, and its potential has poorly been investigated to date. We report the case of an adult patient with disseminated medulloblastoma and fulminant neurological deterioration, precluding craniospinal irradiation. Emergency chemotherapy consisting of carboplatin (400 mg/m2) and etoposide (500 mg/m2) with intrathecal (i.t.) administration of cytosar and hydrocortisone was initiated. Impressive clinical response was achieved after the first cycle of chemotherapy, with the complete disappearance of the lesions detected by MRI. After 3 courses of chemotherapy, the patient underwent craniospinal irradiation (36 Gy to the entire neuraxis and 54 Gy to the posterior fossa). Two years after surgery, the patient was well, with complete clinical recovery, and a new MRI confirmed the disappearance of the lesions. Given the dramatic efficacy of the etoposide-carboplatin association (combined with i.t. cytosar), this regimen has to be considered in an emergency setting and seems to be a very attractive candidate to be investigated as first line therapy for poor risk medulloblastoma in adults.

[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.

Medulloblastoma in pediatric age: a single-institution review of prognostic factors

We report a retrospective study of 35 cases of medulloblastoma in pediatric patients treated at our institution during an 18-year period. Ten of the patients were infants (age < 2 years) and 25 were children (age > 2 years). The main factors affecting prognosis were total removal of the tumor (P < 0.01) and tumor stage (P < 0.01). There were no differences between the survival rate of infants and children, infants had a worse prognosis in regard to quality of life than children.

Interaction between human medulloblastomas and foetal rat brain aggregates in vitro

The invasiveness of three medulloblastoma permanent cell lines (D-283, D-341, and DAOY), a human medulloblastoma biopsy, and in addition, a human rhabdomyosarcoma permanent cell line (TE-671), which previously had been regarded as a human medulloblastoma, was studied in an organ co-culture assay. All the four cell lines and the biopsy were co-cultured with normal rat brain cell aggregates for up to six days in vitro. The medulloblastoma biopsy, the D-283 and the D-341 cells invaded the brain tissue by diffuse single cell infiltration. The medulloblastoma cell line (DAOY) showed an invasive pattern similar to that observed earlier for most glioblastoma cell lines. This was characterized by massive cell replacement and destruction of normal brain tissue. The rhabdomyosarcoma cell line (TE-671) presented a solid invasive pattern with a fairly well defined border between normal brain and tumour tissue. Thus, the organ co-culture assay system in vitro seems to mimic several aspects of the in situ invasive behaviour of medulloblastomas. It may, therefore, provide new perspectives for pretreatment investigations with chemotherapy and radiotherapy of these malignancies.