Large Cell Medulloblastoma Research Articles

Clinical Characteristic and Molecular Subgroups of Thai Pediatric Medulloblastomas at Queen Sirikit National Institute of Child Health

Objective: To determine the correlation between clinical characteristics and molecular subgroups of medulloblastoma (MB) in Thai pediatric patients at the Queen Sirikit National Institute of Child Health (QSNICH), Thailand. Materials and Methods: MB specimens operated between 2004 and 2018 were classified by Nanostring into four molecular subgroups, including Wingless signaling pathway (WNT), Sonic Hedgehog signaling pathway (SHH), Group 3, and Group 4. For the present cases, the clinical records were retrospectively analyzed. Results: Twenty-two MB cases with complete clinical records were analyzed. Group 4 was the most common molecular subgroup (31.82%), followed by WNT (27.27%), SHH (22.73%), and Group 3 (18.18%). The histologic subtypes included 18, three, and one cases of classic MB, MB with extensive nodularity (MBEN), and large cell MB, respectively. All SHH MBs were found in infants. All MBENs belonged to SHH subgroup, and the large cell MB was Group 3. All six WNT MB cases did not experience tumor recurrence. Five-year cause specific survival rates were 100% in WNT, 60% in SHH, 57.1% in Group 4, and 0% in Group 3. Five-year recurrence-free survival rates were 100% in WNT, 42.9% in Group 4, and 0% in SHH and Group 3. Conclusion: MB is a heterogeneous disease. Classification of MB, especially at the molecular subtype, is helpful for the management and prognostication. Keywords: Medulloblastoma; Molecular subgroup

MBCL-07. NON-METASTATIC MEDULLOBLASTOMA OF EARLY CHILDHOOD: RESULTS FROM THE PROSPECTIVE CLINICAL TRIAL HIT-2000 AND AN EXTENDED VALIDATION COHORT

OBJECTIVETo avoid craniospinal irradiation (CSI) in children younger than four years with non-metastatic medulloblastoma by chemotherapy, intraventricular methotrexate and risk-adapted local radiotherapy.PATIENTS AND METHODSEighty-seven patients received systemic chemotherapy and intraventricular methotrexate. Until 2006, CSI was reserved for non-response or progression. After 2006, local radiotherapy was introduced for non-responders or classic (CMB), anaplastic or large-cell medulloblastoma (LCA). Infantile SHH-activated medulloblastomas (SHH_INF) were subdivided by DNA-methylation profiling. Survival in SHH_INF subtypes were also assessed in a validation cohort (n=71).RESULTSPatients with desmoplastic medulloblastoma (DMB) or medulloblastoma with extensive nodularity (MBEN) (n=42) had 93% 5-year PFS, 100% 5-year OS and 93% 5-year CSI-free survival. Patients with CMB/LCA (n=45) had 37% 5y-PFS, 62% 5y-OS and 39% 5y-CSI-free survival. Local radiotherapy did not improve survival in CMB/LCA patients. All DMB/MBEN assessed by DNA methylation profiling belonged to the SHH_INF subgroup. Group 3 patients (5y-PFS 36% [n=14]) relapsed more frequently than SHH_INF (5y-PFS 93% [n=28]) or Group 4 patients (5y-PFS 83% [n=6], p<0.001). SHH_INF split into iSHH-I and iSHH-II subtypes in HIT-2000-BIS4 and the validation cohort, without prognostic impact (5y-PFS: iSHH-I 73% vs. iSHH-II 83%, p=0.25, n=99). Mean IQ was 90 (radiotherapy-free survivors) vs. 74 (patients that received CSI) [p=0.012].CONCLUSIONSystemic chemotherapy and intraventricular methotrexate led to favorable survival in both iSHH-subtypes of SHH-activated DMB/MBEN with acceptable neurotoxicity. Survival in non-WNT/non-SHH CMB/LCA patients was not improved by local radiotherapy. Survival was more favorable in patients with Group 4 than in patients with Group 3 medulloblastoma.

Survival in adult and pediatric patients with medulloblastoma: A 2018 SEER-based analysis.

e14529 Background: Medulloblastoma (MB) is a malignant neuroectodermal tumor accounting for 30% of pediatric and only 1% of adult brain tumors. In previous studies comparing survival in pediatric and adult MB from the National Cancer Institute Surveillance Epidemiology and End Results (SEER) database no difference has been found. However, diagnostic subgroup analyses have been limited. Methods: We examined survival in children (age 0-19) and adults (20-79) coded as MB in the 2018 SEER database (2000-2016). We used Kaplan Meier analysis, log-rank test and Cox proportional hazard ratios (HR) with 95% confidence intervals (CI). MB in SEER-18 is defined as ICD-O-3 histology codes 9470–9474 (n = 1,728). ICD 9473, supratentorial PNET (sPNET, n = 97) is biologically distinct and therefore it was analyzed separately. Results: We found that 5-year survival for MB, excluding sPNET, was similar in children (n = 1,091, 75.3%) and adults (n = 488, 79.1%) (HR = 0.97, CI: 0.79 – 1.17, p = 0.50). Furthermore, subtype analyses showed no survival difference comparing adults and children with desmoplastic nodular MB (n = 222, p = 0.09), large cell MB (n = 73, p = 0.46), or MB NOS (n = 1330, p = 0.10). Yet, children with sPNET had improved 5-year survival (n = 65, 72.3%) compared to adults (n = 29, 51.7%) (HR = 2.0, CI: 1.10 – 3.92; p = 0.02,). These findings indicate that while survival in patients with MB is similar across age groups, children with sPNET have improved outcomes. Conclusions: In summary, 2018 SEER data for MB continue to show no survival difference between adults and children, suggesting adult patients could appropriately be entered on pediatric MB treatment protocols. Further analyses of the 2018 data are ongoing adjusting for sex, race, and treatment (chemotherapy or radiation). For sPNET, the apparent improved outcomes for children merit further detailed investigation and will be re-evaluated using the new 2016 World Health Organization classification.

Demographics, patterns of care, and survival in pediatric medulloblastoma.

We evaluated the American College of Surgeon's National Cancer Data Base (NCDB) to describe current hospital-based epidemiologic frequency, survival, and patterns of care of pediatric medulloblastoma. We analyzed NCDB 1998-2011 data on medulloblastoma for children ages 0-19 years using logistic and poisson regression, Kaplan-Meier survival estimates, and Cox proportional hazards models. 3647 cases of medulloblastoma in those aged 0-19 years were identified. Chemotherapy was received by 79 and 74% received radiation, with 65% receiving both therapies. Those who received radiation were more likely to be older than four, while those who received chemotherapy were more likely to be age four and younger. Variables associated with receipt of neither radiation nor chemotherapy included age at diagnosis of <1 year, female gender, being of race other than black or white, having no insurance, and living in a residential area with a low level of high school graduates. Better overall survival was observed as age at diagnosis increased, in females, and having received radiation. Compared to medulloblastoma, NOS, better survival was observed for those with demoplastic medulloblastoma, with worse survival in those with large cell medulloblastoma. Majority received multi- disciplinary therapy and radiation had the greatest effect on survival. Ages four and under were most likely to receive chemotherapy and least likely to receive radiation. Suboptimal treatment included 17.8% that did not receive chemotherapy, of which 11.8% received neither chemotherapy nor radiation. Disparities associated with medical access were characteristics for not receiving standard treatment, which resulted in poor outcome.

SHP2, SOCS3 and PIAS3 Expression Patterns in Medulloblastomas: Relevance to STAT3 Activation and Resveratrol-Suppressed STAT3 Signaling.

Background: Activated STAT3 signaling is critical for human medulloblastoma cells. SHP2, SOCS3 and PIAS3 are known as the negative regulators of STAT3 signaling, while their relevance to frequent STAT3 activation in medulloblastomas remains unknown. Methods: Tissue microarrays were constructed with 17 tumor-surrounding noncancerous brain tissues and 61 cases of the classic medulloblastomas, 44 the large-cell medulloblastomas, and 15 nodular medulloblastomas, which were used for immunohistochemical profiling of STAT3, SHP2, SOCS3 and PIAS3 expression patterns and the frequencies of STAT3 nuclear translocation. Three human medulloblastoma cell lines (Daoy, UW228-2 and UW228-3) were cultured with and without 100 μM resveratrol supplementation. The influences of resveratrol in SHP2, SOCS3 and PIAS3 expression and SOCS3 knockdown in STAT3 activation were analyzed using multiple experimental approaches. Results: SHP2, SOCS3 and PIAS3 levels are reduced in medulloblastomas in vivo and in vitro, of which PIAS3 downregulation is more reversely correlated with STAT3 activation. In resveratrol-suppressed medulloblastoma cells with STAT3 downregulation and decreased incidence of STAT3 nuclear translocation, PIAS3 is upregulated, the SHP2 level remains unchanged and SOCS3 is downregulated. SOCS3 proteins are accumulated in the distal ends of axon-like processes of resveratrol-differentiated medulloblastoma cells. Knockdown of SOCS3 expression by siRNA neither influences cell proliferation nor STAT3 activation or resveratrol sensitivity but inhibits resveratrol-induced axon-like process formation. Conclusion: Our results suggest that (1) the overall reduction of SHP2, SOCS3 and PIAS3 in medulloblastoma tissues and cell lines; (2) the more inverse relevance of PIAS3 expression with STAT3 activation; (3) the favorable prognostic values of PIAS3 for medulloblastomas and (4) the involvement of SOCS3 in resveratrol-promoted axon regeneration of medulloblastoma cells.

Analysis of pathologic characteristics and prognosis in different subtypes of adult medulloblastoma

To study the pathologic characteristics and prognosis in different subtypes of adult medulloblastoma (MB). The clinical information, imaging findings and pathologic characteristics of 151 cases of adult medulloblastomas were retrospectively reviewed and analyzed by chi-square test. The survival data were assessed using the Kaplan-Meier method. Amongst the 151 MB cases studied, there were 73 cases of classic MB, 36 cases of desmoplastic/nodular MB, 39 cases of anaplastic MB and 3 cases of large cell MB. The primary tumors were more frequently located in cerebral hemisphere in desmoplastic/nodular MB than in other subtypes (P=0.000).On the other hand, large cell/anaplastic MB were associated with more frequently local recurrence and distant metastasis (P=0.003). The post-operative overall survival time ranged from 6 to 150 months, with median survival being (103.3±5.7) months (95%CI, 92.52 to 115.09). The median survival of classic MB, desmoplastic/nodular MB and large cell/anaplastic MB was (110.7±7.8) months, (125.5±7.6) months and (57.6±7.6) months, respectively. The differences were statistically significant (P=0.000). The three variants of MB show different biologic behavior. Large cell/anaplastic MB represents an independent poor prognostic indicator in adults.

CTNNB1, AXIN1 and APC expression analysis of different medulloblastoma variants

OBJECTIVES:We investigated four components of the Wnt signaling pathway in medulloblastomas. Medulloblastoma is the most common type of malignant pediatric brain tumor, and the Wnt signaling pathway has been shown to be activated in this type of tumor.METHODS:Sixty-one medulloblastoma cases were analyzed for β-catenin gene (CTNNB1) mutations, β-catenin protein expression via immunostaining and Wnt signaling pathway-related gene expression. All data were correlated with histological subtypes and patient clinical information.RESULTS:CTNNB1 sequencing analysis revealed that 11 out of 61 medulloblastomas harbored missense mutations in residues 32, 33, 34 and 37, which are located in exon 3. These mutations alter the glycogen synthase kinase-3β phosphorylation sites, which participate in β-catenin degradation. No significant differences were observed between mutation status and histological medulloblastoma type, patient age and overall or progression-free survival times. Nuclear β-catenin accumulation, which was observed in 27.9% of the cases, was not associated with the histological type, CTNNB1 mutation status or tumor cell dissemination. The relative expression levels of genes that code for proteins involved in the Wnt signaling pathway (CTNNB1, APC, AXIN1 and WNT1) were also analyzed, but no significant correlations were found. In addition, large-cell variant medulloblastomas presented lower relative CTNNB1 expression as compared to the other tumor variants.CONCLUSIONS:A small subset of medulloblastomas carry CTNNB1 mutations with consequent nuclear accumulation of β-catenin. The Wnt signaling pathway plays a role in classic, desmoplastic and extensive nodularity medulloblastoma variants but not in large-cell medulloblastomas.

Supratentorial Primitive Neuroectodermal Tumors (PNETs) and Medulloblastoma in Children and the Elderly: A Surveillance, Epidemiology, and End Results (SEER) Investigation of Prognosis, Tumor Characteristics, and Predictors of Radiation Therapy

Medulloblastoma and supratentorial PNET predominantly occur in children. Variations in histology, location, prognosis, and radiation treatment (RT) by age are poorly understood. Additionally, a significant portion of patients >3 years (y) do not undergo RT, and we attempted to determine factors associated with this treatment strategy. Using the SEER 1973-2008 database, we identified 2999 CNS supratentorial PNET/pineoblastomas (14.7%) and medulloblastomas (85.3%). Multivariate analysis (covariates: age, sex, tumor site, stage, histology, extent of surgery, RT, and diagnosis year) with Cox proportional hazards and logistic regression identified predictors of survival and radiation treatment, respectively. Median follow-up was 45 months (range 1-428). At diagnosis, age distributions were <3 (N=490), 3-17 (N=1560), 18-34 (N=604), 35-64 (N=315), and ≥65y (N=30). For ≥65 vs. <18y, there were more pineoblastomas (33.3% vs. 4.4%), supratentorial tumors (60.0% vs. 12.8%), and no surgical resection (36.7% vs. 4.8%); all P<0.001. By age, RT administration was: <3 (34.8%), 3-17 (86.9%), 18-34 (85.5%), 35-64 (83.3%), and ≥65y (60.0%); P<0.001. 5y overall (OS) and disease specific survival (DSS) were 60.3% and 63.1%. Histologies with worse 5y OS were supratentorial PNET (40.1%), pineoblastomas (53.5%), and large cell medulloblastomas (53.7%). By location, 5y OS was 65.0% for infratentorial, 47.2% for supratentorial, and 48.7% for primary spinal cord lesions. When examining 5y DSS by age group, elderly patients had the lowest DSS (17.5%), followed by <3 (47.8%), 3-17 (67.5%), 18-34 (67.0%), and 35-64y (59.9%). In multivariate analysis (3-17y reference, HR=1), patients <3 (HR 1.34), 35-64 (HR 1.50), and ≥65 (HR 2.16) had worse DSS (P<0.01). 5y OS with and without RT was 64.9% and 43.8%, respectively (P<0.001). For DSS after adjustment, significant (P<0.05) disease factors associated with decreased survival were supratentorial location (HR 1.79), distant metastases (HR 1.73), PNET histology (HR 1.58) and large cell medulloblastoma (HR 2.73). Significant treatment factors for improved DSS were gross total resection (HR 0.72) and RT (HR 0.54). In multivariate analysis (3-17y reference OR=1), only age was associated with RT use, with those <3y (OR 0.08) and ≥65 (OR 0.33) less likely to receive RT at initial diagnosis (P<0.05). Characteristics underlying prognosis of supratentorial PNET and medulloblastoma differ by age. Among elderly patients there is a greater proportion of pineoblastomas, supratentorial PNETs, and less aggressive use of surgery and RT, potentially contributing to worse survival in this high-risk population.

Aggressive large cell medulloblastoma extending to the extracranial region in brain-dead state

The authors describe the case of a 29-month-old boy who presented with acute non-communicating hydrocephalus caused by a small tumor in the fourth ventricle. He became brain-dead immediately and remained stable in that condition. Six months later, despite being in a brain-dead state, a rapid direct tumor extension from the intracranial to extracranial region was observed, and chemoradiotherapy was performed following tumor biopsy. The histopathological diagnosis was large cell medulloblastoma. Although treatment was initially effective, the tumor again aggressively invaded the cervical muscles via the spinal canal. Comparative genomic hybridization (metaphase) analysis revealed a pattern of aberrations predictive of a poor prognosis (+1q, ?17p, +17q, and probable amplification of c-myc gene), and he eventually died 11 months after onset. Direct invasion of medulloblastoma from the intracranial to extracranial region is extremely rare, and, to our knowledge, this is the first report of medulloblastoma exhibiting rapid extension to the extracranial region in brain-dead state. For patients with medulloblastomas, careful observation is needed even in brain-dead state. The etiology of this rare condition as well as the genetic characteristics responsible for aggressive tumor behavior are discussed.

Nervous system tumors: Medulloblastoma

Belongs to the primitive neurectodermal tumours (PNET): highly malignant embryonal tumours of the CNS with predominant neuronal differentiation. Several variants medulloblastoma are recognized in the OMS classification: Classic medulloblastoma composed of densely jacked round-cells with round to oval hyperchromatic nuclei. Desmoplastic medulloblastoma represents a variant with abundant reticulin and collagen. Large cell medulloblastoma is a rare variant composed of cells with large round nuclei.

Magnetic resonance imaging spectrum of medulloblastoma

Two medulloblastoma variants were recently added to the WHO classification of CNS tumours. We retrospectively analysed the imaging findings of 37 classic and 27 cases of variant medulloblastomas to identify imaging characteristics that might suggest a particular MB subtype. Sixty-four patients from three institutions were included. Location, tumour margins, signal intensities on conventional MRI, enhancement pattern, the presence of haemorrhage, calcifications and hydrocephalus were recorded and analysed. Signal characteristics on diffusion-weighted MR images and MR spectra were evaluated when available. Thirty-seven classic type of MB (CMB), twelve cases of desmoplastic/nodular medulloblastoma (DMB), nine medulloblastomas with extensive nodularity (MB-EN), five cases of anaplastic and one of large-cell medulloblastoma were included. Fifty of 64 tumours were located in the 4th ventricle region. On T2WI, CMB were all hyperintense, whereas DMB and MB-EN showed isointensity in up to 66%. One third of the classic MB showed only subtle marginal or linear enhancement. All medulloblastoma variants showed marked enhancement. The results of our study suggest: (a) an age-dependent distribution of MB variants, with DMB and MB-EN more common in younger children; (b) a female predominance in DMB; (c) a more common off-midline location in DMB (50%) and MB-EN (33%) variants.

Diffuse postoperative cerebellar swelling in medulloblastoma: report of two cases

We report two cases of diffuse cerebellar swelling with upward transtentorial herniation following medulloblastoma resection. We present our insight for managing medulloblastoma with aggressive clinical behavior. Case 1 is a 32-month-old boy. Magnetic resonance imaging (MRI) revealed fourth ventricular mass with diffuse leptomeningeal metastasis. He underwent gross total resectioning of the tumor and histopathology revealed a large cell medulloblastoma. A ventriculoperitoneal shunt was placed on the 25th postoperative day. Ten days after he developed lethargy, and MRI showed diffuse cerebellar swelling with upward herniation. He underwent emergent posterior fossa decompression; however, he remained unresponsive since then. Case 2 is a 31-month-old boy. MRI revealed a fourth ventricular mass with diffuse leptomeningeal metastasis. He underwent gross total resection and histopathology was a large cell medulloblastoma. Due to developing ventriculomegaly, extraventricular drainage was reinserted on the 11th postoperative day. Four days after, he developed lethargy and decerebrate posturing. MRI showed diffuse cerebellar swelling with upward herniation. He underwent aggressive posterior fossa decompression. Chemotherapy was started postoperatively. Gradually, his movement of extremities improved. On the 79th postoperative day, he started to follow commands and talk some words. He was discharged to a rehabilitation institute and has continued to improve since then. Diffuse cerebellar swelling with upward herniation could occur in patients with aggressive medulloblastoma postoperatively. Our patients had diffuse leptomeningeal dissemination of the tumor at the initial presentation. Close monitoring and prompt diagnosis with earlier surgical posterior fossa decompression and administration of chemotherapy may prevent irreversible neurologic deterioration.

Anti-apoptotic and growth-promoting markers in adult medulloblastomas

the aim of this study was to investigate the pathologic features, proliferation potential and expression of some anti-apoptotic and growth-promoting markers in adult medulloblastomas. we analyzed the immunohistochemical expression of survivin, c-KIT, Bcl-2, fascin, p-53 and Ki-67 in 18 adult medulloblastomas (> 16 years of age). study included 14 males and 4 females (mean age: 22.9 ± 8.2). 14 cases were classical, 2 desmoplastic/nodular and 2 large cell medulloblastomas. Moderate-to-high nuclear survivin expression was observed with high percentages (55 - 100%) in all medulloblastomas while Bcl-2 was mildly positive in only 1 case. Interestingly, mild-to-moderate cytoplasmic c-KIT expression was demonstrated in 16 cases (89%) without membranous accentuation. Fascin expression was observed in 13 medulloblastomas (72%), 9 of which showing moderate to high immunoreactivity. Mild p53 expression was present in only 4 cases (22%). Mean Ki-67 index was 20.6% (range 8 - 55%). frequent nuclear survivin expression implies the predominance of anti-apoptotic factors in pathogenesis of adult medulloblastomas. It may also be a potential therapeutic target for adult medulloblastomas. Although Blc-2 immunoreactivity was previously reported in approximately 30% in medulloblastomas, we have observed that it is rarely expressed in the present series of adult medulloblastomas. To our knowledge, this is the first study evaluating fascin expression in medulloblastomas. Its presence may be related to the neuronal differentiation. Mild-to-moderate cytoplasmic c-KIT immunoreactivity without membranous staining in adult medulloblastomas may support the previous studies reporting low level of c-KIT protein expression with lack of activating mutations in medulloblastomas. It seems p53 is rarely involved in the course of develepment of adult medulloblastomas.

High‐risk medulloblastoma: Does c‐myc amplification overrule histopathology?

High‐risk medulloblastoma: Does <i>c‐myc</i> amplification overrule histopathology?

PARP1 expression in pediatric central nervous system tumors

Despite advances in therapy, outcome in many high-grade pediatric central nervous system (CNS) tumors remains poor. The focus of neuro-oncology research has thus turned towards identifying novel therapeutic targets. Poly(ADP-ribose) polymerase-1 (PARP1) is a DNA repair protein that has been studied in a variety of malignancies and may interfere with therapy-induced DNA damage, however expression in pediatric CNS tumors is unknown. We evaluated PARP1 mRNA expression in 81 pediatric CNS tumors using microarray technology. Protein expression was examined by Western blot. PARP1 mRNA is highly expressed in high-grade tumors (P < 0.0001). PARP1 mRNA expression was greater in high-grade glioma than pilocytic astrocytoma (P = 3.5 x 10(-5)) and in large cell medulloblastoma over classic medulloblastoma (P = 0.0053). PARP1 protein was also prominent in high-grade tumors (P = 0.022). These findings indicate that PARP1 is expressed in high-grade pediatric CNS tumors, implicating PARP1 inhibition as a potential therapeutic target.

Occult leptomeningeal large cell medulloblastoma in an adult

Large cell medulloblastoma is an uncommon malignancy of childhood that often pursues an aggressive clinical course. We report the first case of this entity in an adult that proved to be an unsuspected primary leptomeningeal tumor. A 30-year-old man complained of worsening neck pain over the course of 3 months. Neck pain increased a few days prior to admission and a cervical spine CT revealed tonsillar herniation. Cervical spine MRI performed the day prior to admission confirmed the diagnosis of Chiari I malformation and C3-4 disk herniation without spinal cord compression. On the day of admission, the patient became unresponsive and resuscitative measures were unsuccessful. Postmortem examination of the brain was notable for necrotic cerebellar tonsils, but demonstrated no evidence of an intraparenchymal mass lesion. Microscopic examination of the cerebellum revealed discohesive neoplastic cells, which showed characteristic dot-like immunoreactivity for synaptophysin, diagnostic of large cell medulloblastoma within the subarachnoid space. Our experience with this unique case illustrates the challenges of diagnosing a primary leptomeningeal neoplasm. This case also underscores the importance of maintaining a high degree of suspicion for leptomeningeal neoplasms in patients who present with imaging studies suspicious for Chiari I malformation.

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.

Large cell medulloblastoma with myogenic and melanotic differentiation: a case report with molecular analysis

We present a case of large cell medulloblastoma with myogenic and melanotic differentiation arising in the cerebellar vermis of a 2-year-old boy and following an aggressive clinical course. Histologic and immunohistochemical features of this tumor include primitive neuronal, rhabdomyoblastic, and pigmented epithelial elements, along with large cell features. Immunohistochemical and molecular data (c-myc gene amplification and the presence of isochromosome 17q) support the contention that this histologically diverse tumor represents a pattern of medulloblastoma with striated muscle and pigmented epithelial differentiation, rather than a teratoma or a cerebellar variant of melanotic neuroectodermal tumor of infancy ('progonoma').

Functional and molecular interactions between the HGF/c-Met pathway and c-Myc in large-cell medulloblastoma

The growth factor hepatocyte growth factor (HGF), also known as scatter factor, and its tyrosine kinase receptor c-Met play important roles in medulloblastoma malignancy. The transcription factor c-Myc is another contributor to the malignancy of these most common pediatric brain tumors. In the present study, we observed strong morphological similarities between medulloblastoma xenografts overexpressing HGF and medulloblastoma xenografts overexpressing c-Myc. We therefore hypothesized a biologically significant link between HGF/c-Met and c-Myc in medulloblastoma malignancy and studied the molecular and functional interactions between them. We found that HGF induces c-Myc mRNA and protein in established and primary medulloblastoma cells. HGF regulated c-Myc levels via transcriptional and post-transcriptional mechanisms as evidenced by HGF induction of c-Myc promoter activity and induction of c-Myc protein levels in the setting of inhibited transcription and translation. We also found that HGF induces cell cycle progression, cell proliferation, apoptosis and increase in cell size in a c-Myc-dependent manner. Activation of MAPK and PI3K, inhibition of GSK-3β and translocation of β-catenin to the nucleus as well as Tcf/Lef transcriptional activity were involved in mediating c-Myc induction by HGF. Induction of Cdk2 kinase activity was involved in mediating the cell cycle progression effects, and downregulation of Bcl-XL was involved in mediating the proapoptotic effects of HGF downstream of c-Myc. All molecules that mediated the effects of HGF on c-Myc expression, cell proliferation and apoptosis were expressed in human large-cell medulloblastoma tissues. We therefore established for the first time a functional cooperation between HGF/c-Met and c-Myc in human medulloblastoma and elucidated the molecular mechanisms of this cooperation. The findings provide a potential explanation for the high frequency of c-Myc overexpression in medulloblastoma and suggest a cooperative role for c-Met and c-Myc in large-cell anaplastic medulloblastoma formation.

Do medulloblastoma tumors meet the food and drug administration criteria for anti‐erbB2 therapy with trastuzumab?

Several publications have recently focused on the erbB2 receptor in pediatric medulloblastomas (MBs) and its prognostic consequence. We determined erbB2 expression in 23 MBs at diagnosis. After DNA extraction, quantitative PCR targeting the erbB2 gene was performed and correlated with FISH analysis and immunohistochemistry. The samples were representative of the spectrum of the disease apart from the absence of large cell MBs. Using the tools validated for breast cancers by the FDA, we did not observe any expression or amplification of erbB2 and hence we speculate that MBs are not a good target for treatment with anti-erbB2 antibodies.