Medulloblastomas with systemic metastases: evaluation of tumor histopathology and clinical behavior in 23 patients

An Adult Case of Medulloblastoma with Multiple Lung Metastatic Lesions-Case Report and Literature Review

Medulloblastoma (MB) cerebelli is a common brain tumor of the childhood. MB commonly spreads through cerebrospinal fluid; however, there are several reported cases of extracranial spread. The most common sites of extracranial metastasis are bones and bone marrow followed by peritoneum, liver, and lungs. Here, we report a case of pulmonary metastatic lesions of adult cerebellar MB that were discovered 1 year after the primary surgical treatment. We also tried to highlight similar reported cases in the literature.

Cervical Lymph Node Metastasis From Medulloblastoma in a Young Adult: Case Report and Literature Review

Medulloblastoma, an embryonal tumor located in the posterior fossa of the brain, originates from the neuro-epidermal layer of the cerebellum. It is the most prevalent malignant tumor in children, while it is rare in adults and predominantly affects males. Multimodal therapeutic interventions, such as surgery, radiotherapy, and chemotherapy, have substantially enhanced the prognosis of this condition. Extraneural metastases are infrequent. We present a case of medulloblastoma relapse with nodal metastasis in a 28-year-old adult.

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.

Medulloblastoma in adults - reviewing the literature from a surgeon's point of view

Medulloblastoma is a common primary brain tumor in children but it is a rare cancer in adult patients. We reviewed the literature, searching PubMed for articles on this rare tumor entity, with a focus on tumor biology, advanced neurosurgical opportunities for safe tumor resection, and multimodal treatment options. Adult medulloblastoma occurs at a rate of 0.6 per one million people per year. There is a slight disparity between male and female patients, and patients with a fair skin tone are more likely to have a medulloblastoma. Patients present with cerebellar signs and signs of elevated intracranial pressure. Diagnostic efforts should consist of cerebral MRI and MRI of the spinal axis. Cerebrospinal fluid should be investigated to look for tumor dissemination. Medulloblastoma tumors can be classified as classic, desmoplastic, anaplastic, and large cell, according to the WHO tumor classification. Molecular subgroups include WNT, SHH, group 3, and group 4 tumors. Further molecular analyses suggest that there are several subgroups within the four existing subgroups, with significant differences in patient age, frequency of metastatic spread, and patient survival. As molecular markers have started to play an increasing role in determining treatment strategies and prognosis, their importance has increased rapidly. Treatment options include microsurgical tumor resection and radiotherapy and, in addition, chemotherapy that respects the tumor biology of individual patients offers targeted therapeutic approaches. For neurosurgeons, intraoperative imaging and tumor fluorescence may improve resection rates. Disseminated disease, residual tumor after surgery, lower radiation dose, and low Karnofsky performance status are all suggestive of a poor outcome. Extraneural spread occurs only in very few cases. The reported 5-year-survival rates range between 60% and 80% for all adult medulloblastoma patients.

Medulloblastoma: Molecular understanding, treatment evolution, and new developments

Medulloblastoma (MB) is the most common childhood malignant brain tumor, accounting for approximately 20% of all pediatric central nervous system tumors. Current standard treatments involving surgical interventions followed by craniospinal irradiation and adjuvant chemotherapy have severe motor and cognitive defects. Therefore, individualized treatment regimens with reduced toxicity designed according to the presence of specific oncogenic 'driver' genes are urgently demanded. To this end, recent genetic and epigenetic findings have advanced the classification of MB into the international consensus of four distinct MB molecular subgroups (WNT, SHH, Group 3, and Group 4) based on their respective molecular and histopathological characteristics. More recent studies have indicated that up to seven molecular subgroups exist in childhood MB. Moreover, studies on the inter- and intra-tumoral features of the four subgroups revealed that each subgroup contains variant subtypes. These results have greatly helped risk stratification of MB patients at diagnosis and significantly improved clinical treatment options. Herein, we highlight the recent advances and challenges associated with MB classification, and the development of therapeutic treatments targeting novel subgroup-specific molecular and epigenetic factors, especially those in the SHH-driven MB tumors.

Imaging features of medulloblastoma: Conventional imaging, diffusion-weighted imaging, perfusion-weighted imaging, and spectroscopy: From general features to subtypes and characteristics

Medulloblastoma is a frequent high-grade neoplasm among pediatric brain tumours. Its classical imaging features are a midline tumour growing into the fourth ventricle, hyperdense on CT-scan, displaying a hypersignal when using diffusion-weighted imaging, with a variable contrast enhancement. Nevertheless, atypical imaging features have been widely reported, varying according to the age of the patient, and histopathological subtype. In this study, we review the classical and atypical imaging features of medulloblastomas, with emphasis on advanced MRI techniques, histopathological and molecular subtypes and characteristics, and follow-up modalities.

A case of early extraneural medulloblastoma metastases in a young adult

Extraneural metastases are a relatively rare manifestation of the primary brain tumors, and a major part of the cases has been associated with initial medulloblastoma. Herein, we present the case of a young female adult diagnosed and operated for medulloblastoma. The patient developed extraneural metastases in the first postoperative year. The condition exhibited an aggressive course of development, and the applied treatment approaches were unable to halt its progression. A short literature review identifies the predictive factors determining both prognosis and treatability of the condition; the current limitations and future perspectives of the treatment options are discussed.

Extraneural metastases of medulloblastoma: desmoplastic variants may have prolonged survival

BACKGROUND

Extraneural metastases from CNS medulloblastoma are rare and poorly described. The purpose of this study is to describe the clinical and radiological characteristics of a large single institution series of patients with medulloblastoma who developed extraneural metastases.

PROCEDURE

We retrospectively reviewed a departmental database over a 20 year period for all patients with medulloblastoma who developed extraneural metastases. Chart and imaging reviews were performed, and overall survival (OS) estimated by the Kaplan-Meier method.

RESULTS

We found 14 patients with medulloblastoma and extraneural metastases. The median age at initial diagnosis was 16.3 years (range, 3.2-44.2), and the most common subtype was desmoplastic (n = 6, 42.9%). After initial gross total resection, most patients received radiation therapy alone (n = 10, 71.4%). Metastases to bone were most common (n = 11, 78.6%) followed by metastases to bone marrow (n = 6, 42.9%), usually to the spine. The median time from initial diagnosis to first extraneural metastasis was 1.5 years (range, 0.2-17.4), and the median OS from extraneural metastasis to death was 3.3 years (range, 0-18). The Kaplan-Meier estimate of 5 year OS from extraneural metastasis diagnosis was 40.0% (95% CI, 20.2-79.2).

CONCLUSIONS

Extraneural metastases from medulloblastoma may rarely develop after initial diagnosis to involve bone and bone marrow. We found that desmoplastic variant extraneural tumors had longer survival than nondesmoplastic variants, suggesting that histopathological and more recent molecular subtyping have important roles in determining the prognosis of medulloblastoma patients.

Bone metastases in medulloblastoma--single institution experience

BACKGROUND

Medulloblastoma has one of the highest rates of metastasis outside the central nervous system (CNS). Bone metastases are the most common lesions, although lymph node and visceral spread have also been reported.

OBJECTIVE

To present patients with bone metastasis in medulloblastoma and discuss their radiologic appearances and treatment approach.

PATIENTS AND METHODS

From 1993 to 2008, 82 patients diagnosed with medulloblastoma were treated at the Institute for Oncology and Radiology of Serbia. Three (3.6%) developed extraneural metastasis (ENM). In primary treatment, patients were treated with surgery, craniospinal radiotherapy with local boost to tumor bed, and adjuvant chemotherapy [lomustine (CCNU) and vincristine]. Of the three patients with ENM, all developed bone metastases at the time of relapse. Relapse occurred within 17 to 42 months of initial diagnosis. Patients received secondary chemotherapy and palliative radiotherapy to the affected bone in two cases.

RESULTS

Among these three patients, case 1 had initially a solitary lytic lesion. Case 2 had diffuse blastic lesions and also bone marrow involvement. Case 3 had multiple mixed lytic-sclerotic lesions but later developed lymph node metastasis and metastases to both breasts, as well. All patients were without concurrent CNS involvement at the time of ENM. Unfortunately, after initial partial response, the three patients died at 24, 13, and 18 months after detection of metastases, respectively.

CONCLUSION

With prolonged survival times in children with medulloblastoma, more emphasis should be placed on the possibility of systemic involvement. A greater understanding of the pathogenesis of the systemic metastases may be valuable in designing future, more aggressive multimodal therapy.

Cutaneous metastases from internal malignancies: a clinicopathologic and immunohistochemical review

Skin metastases occur in 0.6%-10.4% of all patients with cancer and represent 2% of all skin tumors. Skin metastases from visceral malignancies are important for dermatologists and dermatopathologists because of their variable clinical appearance and presentation, frequent delay and failure in their diagnosis, relative proportion of different internal malignancies metastasizing to the skin, and impact on morbidity, prognosis, and treatment. Another factor to take into account is that cutaneous metastasis may be the first sign of clinically silent visceral cancer. The relative frequencies of metastatic skin disease tend to correlate with the frequency of the different types of primary cancer in each sex. Thus, women with skin metastases have the following distribution in decreasing order of frequency of primary malignancies: breast, ovary, oral cavity, lung, and large intestine. In men, the distribution is as follows: lung, large intestine, oral cavity, kidney, breast, esophagus, pancreas, stomach, and liver. A wide morphologic spectrum of clinical appearances has been described in cutaneous metastases. This variable clinical morphology included nodules, papules, plaques, tumors, and ulcers. From a histopathologic point of view, there are 4 main morphologic patterns of cutaneous metastases involving the dermis, namely, nodular, infiltrative, diffuse, and intravascular. Generally, cutaneous metastases herald a poor prognosis. The average survival time of patients with skin metastases is a few months. In this article, we review the clinicopathologic and immunohistochemical characteristics of cutaneous metastases from internal malignancies, classify the most common cutaneous metastases, and identify studies that may assist in diagnosing the origin of a cutaneous metastasis.

Low-grade bone lesions in survivors of childhood medulloblastoma/primitive neuroectodermal tumor

OBJECTIVES AND RATIONALE

Medulloblastoma/primitive neuroectodermal tumor (MB/PNET) is the most common malignant tumor of the central nervous system (CNS) in children. MB/PNET survivors are at an increased risk for developing second malignancies. Little has been reported on development of low-grade lesions of the calvarium in the radiation field in MB/PNET survivors. The purpose of this study was to assess the frequency of the low-grade bone lesion development in the radiotherapy field in pediatric MB/PNET survivors and describe the imaging characteristics of these lesions.

MATERIALS AND METHODS

Institutional review board approval was obtained for this retrospective review which was compliant with Health Insurance Portability and Accountability Act. Forty-one MB/PNET patients (29 male) who survived for at least 2 years after initiation of radiation therapy were included. The medical records were reviewed. The most recent available brain magnetic resonance imaging studies were evaluated.

RESULTS

Three patients (7.3%) developed low-grade calvarial lesions and underwent resection and/or biopsy of the lesions. There were one Langerhans cell histiocytosis, one benign spindle cell lesion with myxoid change, and one fibrous dysplasia.

CONCLUSION

Development of low-grade bone lesions of calvarium is not very rare in pediatric PNET/MB survivors. Bones in the radiation therapy field need to be carefully examined for assessment of secondary lesions.

A Rare Case of Adult Medulloblastoma with Spinal Metastasis

Medulloblastoma is a relatively common malignant brain tumor of childhood and relatively rare in adulthood, with a propensity for neuraxial spread via cerebrospinal fluid pathways. Osseous extraneural metastasis is uncommon and when it happens, radiologic findings are of sclerotic (60%), lytic (35%), and mixed patterns (5%) (Algra et al. (1992)). In this paper, we present a case of medulloblastoma metastiaszing to the lumbar spine and describe the magnetic resonance appearance, with emphasis on the image findings mimicking spondylodiscitis.

Extraneural metastases in medulloblastoma

Medulloblastoma is the most common childhood malignant tumor of central nervous system, but it may also occur in adults. It presents high invasive growth with spreading of tumor cells into the leptomeningeal space along the neuroaxis early in the course of the disease. Extraneural metastases are rare but frequently lethal, occurring only in 1 to 5% of patients, and are related, in the most of cases, to the presence of ventriculoperitoneal shunt. Here we characterize the clinical profile of five cases of medulloblastoma with systemic spreading of tumor cells, also comparing them to cases already described in the literature.

Long-term survival in a pediatric patient with supratentorial primitive neuro-ectodermal tumor and extraneural metastasis at diagnosis

Extraneural metastases of central nervous system (CNS) tumors are rare occurrences most commonly observed in medulloblastomas. Survival outcomes are generally dismal. Supratentorial primitive neuroectodermal tumors (stPNET) are rare childhood tumors with few documented cases of extraneural metastases. We present a rare occurrence of a 23-month-old patient with long-term survival after diagnosis of stPNET with metastases to the lungs. This patient was treated with surgical resection, induction chemotherapy, tandem autologous hematopoietic cell rescues, and focal radiotherapy. We report long-term survival for a patient with a stPNET and extraneural metastases at diagnosis following an intensive approach to treatment.

Use of T2 signal intensity of cerebellar neoplasms in pediatric patients to guide preoperative staging of the neuraxis

OBJECT

The question of whether to obtain routine or selective preoperative imaging of the neuraxis in pediatric patients with cerebellar neoplasms remains a controversial topic. Staging of the neuraxis is generally considered beneficial in patients with neoplasms associated with an elevated risk of leptomeningeal dissemination (LD). When these studies are obtained preoperatively, there is a decrease in the number of false-positive images related to debris in the immediate postoperative period. Additionally, knowledge of the extent of spread has the potential to affect the risk/benefit analysis of aggressive resection. Although the majority of pediatric neurosurgeons surveyed choose to obtain selective preoperative imaging of the neuraxis in cases of cerebellar neoplasms "with findings suggestive of high-grade pathology," an evidence-based protocol in the literature is lacking. The goal of this study was to assess radiological characteristics of tumors with an elevated risk of LD and identify a method to help guide preoperative imaging of the neuraxis.

METHODS

The authors first reviewed the literature to gain an appreciation of the risk of LD of pediatric cerebellar neoplasms based on underlying histopathology and/or grade. Available evidence indicates preoperative imaging of the neuraxis in patients with Grade I tumors to be of questionable utility. In contrast, evidence suggested that preoperative imaging of the neuraxis in patients with Grades II-IV neoplasms was clinically warranted. The authors then evaluated an extensive base of neuroradiological literature to identify possible MR imaging and/or CT findings with the potential to differentiate Grade I from higher-grade neoplasms in pediatric patients. They analyzed the preoperative radiological findings in 50 pediatric patients who had undergone craniotomy for resection of cerebellar neoplasms at Vanderbilt Children's Hospital since 2003 with reference to 7 chosen radiological criteria. Logistic regression models were fit using radiological features to determine the best predictors of Grades II-IV tumors. Receiver operating characteristic methods were used to identify diagnostic properties of the best predictors.

RESULTS

The relative T2 signal intensity (RT2SI), an indirect measure of the water content of the solid component of the tumor, was best able to identify neoplasms with an elevated risk of LD. An RT2SI value of 0.71 was selected by the authors as the best operating point on the curve. Of the 31 neoplasms retrospectively designated as hypointense T2-weighted lesions (RT2SI ≤ 0.71), 30 (97%) were Grade II or higher. All medulloblastomas, ependymomas, and high-grade (Grades III and IV) neoplasms were hypointense T2-weighted lesions. Of the 19 T2-weighted hyperintense neoplasms (RT2SI > 0.71), 16 (84%) were Grade I and 3 were Grade II.

CONCLUSIONS

Measurement of the RT2SI can help predict Grade II-IV tumors at an elevated risk of leptomeningeal spread and guide staging of the neuraxis. Pediatric patients with cerebellar neoplasms found to have an RT2SI of less than or equal to 0.71 are recommended for neuraxis imaging prior to surgery.

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.

Accumulation of genomic aberrations during clinical progression of medulloblastoma

Medulloblastomas comprise the most frequent malignant brain tumor in childhood and one of the biggest challenges in pediatric oncology. The current concept suggests that these tumors may undergo stepwise progression as it has been shown for other brain tumors. However, conclusive evidence of molecular progression over time has not been demonstrated yet for medulloblastoma. In the present study, 28 pairs of medulloblastoma at primary diagnosis and at the time of recurrence, either occurring as local tumor regrowth or tumor dissemination, were histopathologically and molecularly analyzed. Cytogenetic analysis included interphase fluorescence in situ hybridization for five genomic loci (MYC, MYCN, 17p, 17q, 6q) that have previously been identified as prognostic markers in primary tumors. Of 16 tumors showing early recurrence (<4 years after first diagnosis), only one showed increased histological anaplasia in the secondary lesion (6%), and two acquired genomic lesions indicative for a more malignant phenotype (13%). In contrast to this, of 12 tumors with a time to recurrence of 4 years or more, nine tumors (75%) showed a more malignant phenotype either reflected by increased anaplasia alone or by both increased anaplasia and acquirement of genomic aberrations known to be associated with inferior patient outcome. These results suggest that early recurrence in medulloblastoma mainly occurs in tumors with a highly malignant genotype and phenotype per se, whereas late recurrence is often dependent on tumor evolution toward a more malignant biology. Therefore, biopsy of recurrent tumors should be performed to assess the biologic properties of the relapsed tumor, especially when targeted therapy approaches are considered.

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.

Medulloblastoma: tumorigenesis, current clinical paradigm, and efforts to improve risk stratification

Medulloblastoma is the most common brain malignancy in children and tremendous advances have recently been made in understanding the pathogenesis of this tumor. The Hedgehog and Wingless signaling pathways are implicated in medulloblastoma development, and both pathways were discovered as a result of analyses of genetic syndromes associated with the tumor. Over the past 80 years, considerable progress has been made in the treatment of what was once a fatal disease. The first survival reports followed the introduction of craniospinal irradiation, and yet the success of this modality, which continues to be a central component of treatment regimens for patients older than 3 years, comes at a significant cost. The present challenge in medulloblastoma treatment is to improve upon existing survival rates and to minimize the side effects of treatment. The current tools of clinical risk assessment fail to adequately identify patients older than 3 years who require less radiation and those who require more radiation. Significant effort has been made to improve clinical risk stratification and titration of treatment by analyzing properties of the tumor cells themselves for prognostic significance. These efforts include identifying histopathologic, cytogenetic, and molecular features that may correlate with prognosis.

Extracentral Nervous System Metastases from Medulloblastoma

Medulloblastoma belongs to the group of highly malignant neuroepithelial tumours and is the commonest tumour in childhood (12–25 %)1, but is rare in adults (0.4–1%) of all primary brain tumours)1,2. Medulloblastomas usually arise in the posterior fossa and spread readily throughout the CSF, although 10–30% of patients develop extracentral nervous system metastases 2. We describe a 30-year-old woman presenting bone metastases from medulloblastoma located predominantly in the spine.

Medulloblastoma simulating acute myeloid leukemia: case report with a review of "myeloid antigen" expression in nonhematopoietic tissues and tumors

Medulloblastoma is a primitive neuroectodermal tumor arising in the posterior fossa usually in the first decade of life. Systemic metastases are infrequent at diagnosis and usually occur after surgical resection or shunt placement. We report a rare case of medulloblastoma in an 18-year-old woman who presented with headache, leukopenia, and anemia. Neurologic examination was normal. Bone marrow evaluation revealed primitive cells morphologically resembling blasts. By flow cytometry, these cells lacked CD45 and expressed CD13/33, CD15, CD34, HLA-DR, and strong CD56. The presence of myeloid antigens and CD34 suggested acute myeloid leukemia; however, the bone marrow core biopsy architecture and tumor cells in cerebrospinal fluid were more compatible with a nonhematopoietic tumor. Further workup revealed a cerebellar mass, and a diagnosis of desmoplastic medulloblastoma was made. To our knowledge, this is the first reported case of a nonhematopoietic small round blue-cell tumor expressing multiple myeloid antigens and CD34 by flow cytometry.

Metastatic tumors in bone marrow: histopathology and advances in the biology of the tumor cells and bone marrow environment

The nonhematopoietic tumors most often diagnosed in the bone marrow are metastatic. Currently, accurate diagnosis of tumor metastasis requires integration of the clinical findings; morphological features; and results of immunohistochemical stains, cytogenetics, and molecular studies. This review focuses on a practical approach to the diagnosis of metastatic tumors in the bone marrow according to current standards of practice and discusses recent advances in understanding of tumor metastasis and the interaction between tumors and the bone marrow environment.

[Medulloblastoma with extracentral nervous system metastases: clinical presentation and risk factors]

PURPOSE

Extra-central nervous system (extra-CNS) metastases are relatively unknown failure patterns in medulloblastoma. The aim of this study was to analyse epidemiological, clinical and aetiopathological aspects of these extra-CNS localisations.

PATIENTS AND METHODS

Extra-CNS metastases were retrospectively identified in patients treated in the department of radiation therapy at Salah-Azaïz institute (ISA) for medulloblastoma. These metastases were diagnosed as extra-CNS for all secondary localisations not related to other tumour aetiology. Aetiopathological aspects are discussed with a literature review.

RESULTS

Among 103 patients treated and followed-up in the department of radiation therapy of ISA from 1970 to 1992, 8 developed extra-CNS metastases (7.7%). Age at diagnosis of primitive tumour varied from 3 to 23 years. Sex ratio was 1. Primitive tumour treatment was: complete surgical resection in 4 patients with preoperative cerebrospinal fluid shunting in two, cerebrospinal axis irradiation in 7 patients and a cerebral-limited irradiation in 1. Two patients received chemotherapy for their initial treatment (systemic in one case and intrathecal in the other). The mean free-interval from diagnosis of primitive tumour to extra-CNS metastases was 23 months, varying from 8 to 53 months. These metastases were located in the liver (1 case), cervical lymph nodes (2 cases), bone marrow (1 case) and bone (2 cases). Two patients had multiple metastases: bone and bone marrow (in one), lung, pleura, cervical lymph node and bone localisations (in one). Treatment of these metastases was: chemotherapy in 5 cases, chemotherapy and radiation in one, radiation therapy in one and 2 patients were given only supportive care treatment. All patients died or are in progressive disease in less than one year from the diagnosis of extra-CNS metastases.

CONCLUSION

Extra-CNS metastases are not rare and have a poor prognosis. The most commonly involved sites are bone, cervical lymph nodes and bone marrow. A complete work-up at initial diagnosis is recommended to screen early metastases. Literature review showed that histopathologic grading might help to identify groups at risk.

Stratification of medulloblastoma on the basis of histopathological grading

Medulloblastoma (WHO grade IV) is an embryonal tumour of the cerebellum and the most common malignant central nervous system tumour in children. Despite significant advances in treatment, 5-year survival rates are still less than 70%, suggesting the presence of subgroups with different response to radio/chemotherapy. In the present study, we re-evaluated a series of 347 medulloblastomas from the SIOP II clinical trial of the International Society of Paediatric Oncology to identify features predictive of clinical outcome. Relapse free survival for medulloblastomas with severe anaplasia [5-year rate: S(60)=49.5%], was significantly shorter than for tumours with moderate or mild anaplasia S(60)=65.4%; P=0.001). The difference between both groups was even larger when the presence or absence of extensive apoptosis was included (46.5 vs. 66.7%; P=0.0216). Other histological features including nodularity, necrosis, vascular proliferation and the presence of beta-catenin mutations (7% of cases) were not predictive for relapse free survival. These findings indicate that degree of anaplasia is the most significant histologic feature predictive of the survival of medulloblastoma patients.

Extraneural metastasis in intracranial tumors in children: the experience of a single center

Our aim is to evaluate the clinical features and outcomes of children with primary central nervous system (CNS) tumors who develop extraneural metastasis (ENM). We retrospectively evaluated children diagnosed with primary CNS tumors treated at our institution between 1972 and 2004. Of 1,011 patients these tumors, 10 (0.98%) developed ENM. The histopathologic diagnosis was medulloblastoma in six patients, germ cell tumors in two patients, and ependymoma and atypical teratoid rhabdoid tumor (ATRT) in one patient each. In six patients, the primary tumor was located in the posterior fossa; it had a supratentorial location in the patient with ATRT, was located in the sellar and suprasellar region in the two patients with germ cell tumors, and was found in the distal spinal cord in the patient with an ependymoma. In two patients ENM was detected at the time of diagnosis. In other patients ENM developed between 9 and 25 months after diagnosis. Metastatic sites included bone, bone marrow, lung, cervical lymph nodes, liver, and paranasal sinuses. Of the 10 patients who developed ENM, 8 died of their disease 0.27-16.2 months (median, 2.60 months) after it was detected. One patient with dysgerminoma is alive, without disease, 117.80 months after diagnosis of the ENM. One patient with germ cell tumor is alive with disease 11.3 months after diagnosis of the ENM. Systemic metastasis to other extraneural sites is extremely rare in children with intracranial tumors. In our series the rate of ENM is 0.98%. The liver and lung are the most common site for metastasis, followed by the bone and bone marrow. The outcome is poor in patients with CNS tumors with ENM.

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.

Differentiation of classic medulloblastoma into metastatic large cell medulloblastoma with focal rhabdoid differentiation in the absence of posterior fossa recurrence

A case of classic medulloblastoma that metastasized, despite the absence of local recurrence, to extraneural sites 7 years after treatment is reported. The metastases were, in contrast to the primary tumor, of large cell type and displayed abortive myogenic and, in one site, also rhabdoid differentiation. The primary tumor expressed microtubule-associated protein 1B and neuron-specific nuclear protein (NeuN), and was desmin negative. The metastases were also positive for microtubule-associated protein 1B and NeuN, although the expression of the latter marker was weak and/or focal in two of four metastases and absent in the rhabdoid metastasis. They were, in contrast with the primary tumor, all strongly positive for desmin. The hSNF5/INI1 was expressed in the nuclei of all cells of the primary tumor and the metastases, including the one with rhabdoid differentiation. Two metastases were studied by cytogenetics. The composite karyotype of a large cell metastasis was 45~46,XY,add(1)(p36.1),t(2;8)(p21;q24.1),add(3)(q25),t(9;15)(q22;q13),add(12)(p11.2), +1approximately2mar,inc[cp12]/46,XY[12], while the rhabdoid metastasis contained additional changes including monosomy 22. These findings indicate that some rhabdoid (atypical teratoid/rhabdoid) tumors of the cerebellum and medulloblastoma may be histogenetically related.

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.

Survivin, Survivin-2B, and Survivin-deItaEx3 expression in medulloblastoma: biologic markers of tumour morphology and clinical outcome

Survivin is an apoptotic inhibitor that is expressed at high levels in a variety of malignancies. Survivin has four known alternative splice forms (Survivin, Survivin-2B, Survivin-deltaEx3, and Survivin-3B), and the recent literature suggests that these splice variants have unique functions and subcellular localisation patterns. We evaluated 19 fresh-frozen paediatric medulloblastomas for the expression of three Survivin isoforms by quantitative PCR. Survivin was most highly expressed when compared with normal cerebellar tissue. We also investigated Survivin protein expression in 40 paraffin-embedded paediatric medulloblastoma tumours by immunohistochemistry. We found a statistically significant association between the percentage of Survivin-positive cells and histologic subtype, with the large-cell-anaplastic variant expressing Survivin at higher levels than the classic subtype. We also found a statistically significant relationship between the percent of Survivin-positive cells in the tumours and clinical outcome, with higher levels of Survivin correlating with a worse prognosis. In summary, our study demonstrates a role for Survivin as a marker of tumour morphology and clinical outcome in medulloblastoma. Survivin may be a promising future prognostic tool and potential biologic target in this malignancy.

Medulloblastoma: signalling a change in treatment

Medulloblastoma is the most common malignant brain tumour that occurs during childhood. Multimodality treatment regimens have substantially improved survival in this disease; however, the tumour is incurable in about a third of patients with medulloblastoma, and current treatment has a detrimental effect on long-term survivors. Drugs that target cell-signalling pathways provide an alternative to conventional cytotoxic approaches to treatment of cancer. Several pathways have been implicated in medulloblastoma formation, and knowledge of these is now being used to develop new ways of treating children with medulloblastoma.

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.

Medulloblastoma as a first presentation of fanconi anemia

Fanconi anemia is a chromosomal instability syndrome associated with certain congenital abnormalities, defective hemopoiesis, and an increased risk of developing acute myeloid leukemia and some solid tumors. The diagnosis can be made at birth if congenital abnormalities are present but is often made in childhood when hematologic complications develop. The authors report a case of Fanconi anemia diagnosed in a child with no congenital abnormalities and normal bone marrow who first presented with a cerebellar medulloblastoma. The authors discuss diagnostic and therapeutic implications for such malignancies in Fanconi anemia.