The role of the WNT/ß-catenin pathway in central nervous system primitive neuroectodermal tumours (CNS PNETs).

BACKGROUND: Central nervous system primitive neuroectodermal tumours (CNS PNETs) are embryonal tumours occurring predominantly in children. Current lack of knowledge regarding their underlying biology hinders development of more effective treatments. We previously identified WNT/ß-catenin pathway activation in one-third of CNS PNETs, which was potentially linked to a better prognosis. In this study, we have extended our cohort, achieving a statistically significant correlation with prognosis. We additionally investigated the biological effects of WNT/ß-catenin pathway activation in tumour pathogenesis. METHODS: A total of 42 primary and 8 recurrent CNS PNETs were analysed for WNT/ß-catenin pathway status using ß-catenin immunohistochemistry. Genomic copy number and mRNA expression data were analysed to identify a molecular profile linked to WNT/ß-catenin pathway activation. RESULTS: Pathway activation was seen in 26% of CNS PNETs and was significantly associated with longer overall survival. Genes displaying a significant difference in expression levels, between tumours with and without WNT/ß-catenin pathway activation, included several involved in normal CNS development suggesting aberrant pathway activation may be disrupting this process. CONCLUSION: We have identified WNT/ß-catenin pathway status as a marker, which could potentially be used to stratify disease risk for patients with CNS PNET. Gene expression data suggest pathway activation is disrupting normal differentiation in the CNS.

WNT/ß-catenin pathway activation in Myc immortalised cerebellar progenitor cells inhibits neuronal differentiation and generates tumours resembling medulloblastoma.

BACKGROUND: Medulloblastoma is the most common malignant childhood brain tumour. Aberrant activation of the WNT/ß-catenin pathway occurs in approximately 25% of medulloblastomas. However, its role in medulloblastoma pathogenesis is not understood. METHODS: We have developed a model of WNT/ß-catenin pathway-activated medulloblastoma. Pathway activation was induced in a Myc immortalised cerebellar progenitor cell line through stable expression of Wnt1. In vitro and in vivo analysis was undertaken to understand the effect of pathway activation and identify the potential cell of origin. RESULTS: Tumours that histologically resembled classical medulloblastoma formed in vivo using cells overexpressing Wnt1, but not with the control cell line. Wnt1 overexpression inhibited neuronal differentiation in vitro, suggesting WNT/ß-catenin pathway activation prevents cells terminally differentiating, maintaining them in a more 'stem-like' state. Analysis of cerebellar progenitor cell markers demonstrated the cell line resembled cells from the cerebellar ventricular zone. CONCLUSION: We have developed a cell line with the means of orthotopically modelling WNT/ß-catenin pathway-activated medulloblastoma. We provide evidence of the role pathway activation is playing in tumour pathogenesis and suggest medulloblastomas can arise from cells other than granule cell progenitors. This cell line is a valuable resource to further understand the role of pathway activation in tumorigenesis and for investigation of targeted therapies.

Non-invasive detection of glycine as a biomarker of malignancy in childhood brain tumours using in-vivo 1H MRS at 1.5 tesla confirmed by ex-vivo high-resolution magic-angle spinning NMR.

Management of brain tumours in children would benefit from improved non-invasive diagnosis, characterisation and prognostic biomarkers. Metabolite profiles derived from in-vivo MRS have been shown to provide such information. Studies indicate that using optimum a priori information on metabolite contents in the construction of linear combination (LC) models of MR spectra leads to improved metabolite profile estimation. Glycine (Gly) is usually neglected in such models due to strong overlap with myo-inositol (mI) and a low concentration in normal brain. However, biological studies indicate that Gly is abundant in high-grade brain tumours. This study aimed to investigate the quantitation of Gly in paediatric brain tumours using MRS analysed by LCModel, and its potential as a non-invasive biomarker of malignancy. Single-voxel MRS was performed using PRESS (TR 1500 ms, TE 30 ms/135 ms) on a 1.5 T scanner. Forty-seven cases (18 high grade (HG), 17 low grade (LG), 12 ungraded) were retrospectively selected if both short-TE and long-TE MRS (n = 33) or short-TE MRS and high-resolution magic-angle spinning (HRMAS) of matched surgical samples (n = 15) were available. The inclusion of Gly in LCModel analyses led to significantly reduced fit residues for both short-TE and long-TE MRS (p < 0.05). The Gly concentrations estimated from short-TE MRS were significantly correlated with the long-TE values (R = 0.91, p < 0.001). The Gly concentration estimated by LCModel was significantly higher in HG versus LG tumours for both short-TE (p < 1e-6) and long-TE (p = 0.003) MRS. This was consistent with the HRMAS results, which showed a significantly higher normalised Gly concentration in HG tumours (p < 0.05) and a significant correlation with the normalised Gly concentration measured from short-TE in-vivo MRS (p < 0.05). This study suggests that glycine can be reliably detected in paediatric brain tumours using in-vivo MRS on standard clinical scanners and that it is a promising biomarker of tumour aggressiveness.

An investigation of WNT pathway activation and association with survival in central nervous system primitive neuroectodermal tumours (CNS PNET).

Central nervous system primitive neuroectodermal tumours (CNS PNET) are high-grade, predominantly paediatric, brain tumours. Previously they have been grouped with medulloblastomas owing to their histological similarities. The WNT/beta-catenin pathway has been implicated in many tumour types, including medulloblastoma. On pathway activation beta-catenin (CTNNB1) translocates to the nucleus, where it induces transcription of target genes. It is commonly upregulated in tumours by mutations in the key pathway components APC and CTNNB1. WNT/beta-catenin pathway status was investigated by immunohistochemical analysis of CTNNB1 and the pathway target cyclin D1 (CCND1) in 49 CNS PNETs and 46 medulloblastomas. The mutational status of APC and CTNNB1 (beta-catenin) was investigated in 33 CNS PNETs and 22 medulloblastomas. CTNNB1 nuclear localisation was seen in 36% of CNS PNETs and 27% of medulloblastomas. A significant correlation was found between CTNNB1 nuclear localisation and CCND1 levels. Mutations in CTNNB1 were identified in 4% of CNS PNETs and 20% of medulloblastomas. No mutations were identified in APC. A potential link between the level of nuclear staining and a better prognosis was identified in the CNS PNETs, suggesting that the extent of pathway activation is linked to outcome. The results suggest that the WNT/beta-catenin pathway plays an important role in the pathogenesis of CNS PNETs. However, activation is not caused by mutations in CTNNB1 or APC in the majority of CNS PNET cases.

Investigation of chromosome 1q reveals differential expression of members of the S100 family in clinical subgroups of intracranial paediatric ependymoma.

Gain of 1q is one of the most common alterations in cancer and has been associated with adverse clinical behaviour in ependymoma. The aim of this study was to investigate this region to gain insight into the role of 1q genes in intracranial paediatric ependymoma. To address this issue we generated profiles of eleven ependymoma, including two relapse pairs and seven primary tumours, using comparative genome hybridisation and serial analysis of gene expression. Analysis of 656 SAGE tags mapping to 1q identified CHI3L1 and S100A10 as the most upregulated genes in the relapse pair with de novo 1q gain upon recurrence. Moreover, three more members of the S100 family had distinct gene expression profiles in ependymoma. Candidates (CHI3L1, S100A10, S100A4, S100A6 and S100A2) were validated using immunohistochemistry on a tissue microarray of 74 paediatric ependymoma. In necrotic cases, CHI3L1 demonstrated a distinct staining pattern in tumour cells adjacent to the areas of necrosis. S100A6 significantly correlated with supratentorial tumours (P<0.001) and S100A4 with patients under the age of 3 years at diagnosis (P=0.038). In conclusion, this study provides evidence that S100A6 and S100A4 are differentially expressed in clinically relevant subgroups, and also demonstrates a link between CHI3L1 protein expression and necrosis in intracranial paediatric ependymoma.

Congenital abnormalities and clinical features associated with Wilms' tumour: a comprehensive study from a centre serving a large population.

Altogether 156 children treated for Wilms' tumour (WT) between 1970 and 1998 were studied. Sixty-six children, selected only by their attendance at clinic, were carefully examined and the findings compared to those from a case note review of 90 children. Congenital abnormalities were present in 45% of the examined cohort, in 19% of the case notes review group and in 30% overall. Novel findings included the association of WT with Marshall Smith syndrome, developmental delay in 3 of 4 cases of WT (one bilateral) and 1 sibling from consanguineous Pakistani families and another sibling also had leukaemia. The possibility of rare DNA repair or cancer predisposing disorders among these 4 families requires further study. Careful examination and history taking of an unselected patient cohort revealed a higher than expected incidence of clinical abnormalities which may be overlooked if not specifically sought.

Loss of heterozygosity for the short arm of chromosome 7 in sporadic Wilms tumour.

Cytogenetic analysis of Wilms tumours (WT) have shown that abnormalities involving chromosome 7 occur in approximately 25% of tumours. In some cases, these abnormalities involve deletions of the short arm, and are seen as the sole cytogenetic change, strongly suggesting the presence of a tumour suppressor gene in this location. Since loss of heterozygosity (LOH) studies have been crucial in defining chromosomal regions involved in Wilms tumorigenesis, we have analysed 40 sporadic Wilms tumours using a panel of 10 microsatellite polymorphic markers distributed along the length of the chromosome arm. In our series, four tumours (10%) showed allelic loss for 7p markers which is twice the background rate of LOH in WT. The shortest common region of overlap of LOH was located between markers D7S517-D7S503 in band 7p21-15. In one tumour there was evidence for a homozygous, interstitial deletion at a locus within this region. These findings provide strong evidence for the existence of a tumour suppressor gene involved in Wilms tumorigenesis and defines the critical region of the chromosome involved.

Cross-species epigenetics identifies a critical role for VAV1 in SHH subgroup medulloblastoma maintenance.

The identification of key tumorigenic events in Sonic Hedgehog (SHH) subgroup medulloblastomas (MBSHH) will be essential for the development of individualized therapies and improved outcomes. However, beyond confirmation of characteristic SHH pathway mutations, recent genome-wide sequencing studies have not revealed commonly mutated genes with widespread relevance as potential therapeutic targets. We therefore examined any role for epigenetic DNA methylation events in MBSHH using a cross-species approach to candidate identification, prioritization and validation. MBSHH-associated DNA methylation events were first identified in 216 subgrouped human medulloblastomas (50 MBSHH, 28 Wnt/Wingless, 44 Group 3 and 94 Group 4) and their conservation then assessed in tumors arising from four independent murine models of Shh medulloblastoma, alongside any role in tumorigenesis using functional assessments in mouse and human models. This strategy identified widespread regional CpG hypo-methylation of VAV1, leading to its elevated expression, as a conserved aberrant epigenetic event, which characterizes the majority of MBSHH tumors in both species, and is associated with a poor outcome in MBSHH patients. Moreover, direct modulation of VAV1 in mouse and human models revealed a critical role in tumor maintenance, and its abrogation markedly reduced medulloblastoma growth. Further, Vav1 activity regulated granule neuron precursor germinal zone exit and migration initiation in an ex vivo model of early postnatal cerebellar development. These findings establish VAV1 as a critical epigenetically regulated oncogene with a key role in MBSHH maintenance, and highlight its potential as a validated therapeutic target and prognostic biomarker for the improved therapy of medulloblastoma.

Familial hepatoblastoma and APC gene mutations: renewed call for molecular research.

Recent findings have increased our understanding of the molecular mechanisms involved in the pathogenesis of hepatoblastoma and their relationship to the molecular pathology of familial adenomatous polyposis (FAP). Here, we describe hepatoblastoma in siblings who share a gene mutation for FAP inherited from their father. This observation confirms the link between these diseases and has implications for future molecular research. We also raise the question; should other members of 'at-risk' families be screened following a new diagnosis of either hepatoblastoma or FAP?

Characterization of the breakpoints in unbalanced t(5;11)(p15;p15) constitutional chromosome translocations in two patients with beckwith-wiedemann syndrome using fluorescence in situ hybridisation.

Although the majority of patients with Beckwith-Wiedemann syndrome (BWS) have a normal karyotype, the study of those rare patients with a cytogenetic abnormality has given considerable insight into the genetics of this condition. The karyotypic abnormalities found include partial chromosome duplications of paternal origin and maternally derived translocations which usually involve the 11p15 region and provide one of the lines of evidence for the location of the BWS gene(s). Because the extent of the duplicated region in these patients is variable, the phenotypic expression of BWS is presumably due to the presence of a common duplicated region. Two unrelated patients with BWS were both noted to have a similar unbalanced t(5;11)(p15;p14) translocation. The parents in both families were unaffected but both fathers carried a balanced translocation involving the same chromosomes. Since the extent and nature of the duplication apparently determines the complex phenotypes seen in these patients, we undertook a detailed analysis of the extent of the triplicated region using fluorescent in situ hybrisation (FISH). Despite having markedly different phenotypes and presenting in disimilar ways the two patients had apparently identical duplication breakpoints.

Metrics and textural features of MRI diffusion to improve classification of pediatric posterior fossa tumors.

BACKGROUND AND PURPOSE: Qualitative radiologic MR imaging review affords limited differentiation among types of pediatric posterior fossa brain tumors and cannot detect histologic or molecular subtypes, which could help to stratify treatment. This study aimed to improve current posterior fossa discrimination of histologic tumor type by using support vector machine classifiers on quantitative MR imaging features. MATERIALS AND METHODS: This retrospective study included preoperative MRI in 40 children with posterior fossa tumors (17 medulloblastomas, 16 pilocytic astrocytomas, and 7 ependymomas). Shape, histogram, and textural features were computed from contrast-enhanced T2WI and T1WI and diffusivity (ADC) maps. Combinations of features were used to train tumor-type-specific classifiers for medulloblastoma, pilocytic astrocytoma, and ependymoma types in separation and as a joint posterior fossa classifier. A tumor-subtype classifier was also produced for classic medulloblastoma. The performance of different classifiers was assessed and compared by using randomly selected subsets of training and test data. RESULTS: ADC histogram features (25th and 75th percentiles and skewness) yielded the best classification of tumor type (on average >95.8% of medulloblastomas, >96.9% of pilocytic astrocytomas, and >94.3% of ependymomas by using 8 training samples). The resulting joint posterior fossa classifier correctly assigned >91.4% of the posterior fossa tumors. For subtype classification, 89.4% of classic medulloblastomas were correctly classified on the basis of ADC texture features extracted from the Gray-Level Co-Occurence Matrix. CONCLUSIONS: Support vector machine-based classifiers using ADC histogram features yielded very good discrimination among pediatric posterior fossa tumor types, and ADC textural features show promise for further subtype discrimination. These findings suggest an added diagnostic value of quantitative feature analysis of diffusion MR imaging in pediatric neuro-oncology.

Surgical delivery of drug releasing poly(lactic-co-glycolic acid)/poly(ethylene glycol) paste with in vivo effects against glioblastoma.

INTRODUCTION: The median survival of patients with glioblastoma multiforme (astrocytoma grade 4) remains less than 18 months despite radical surgery, radiotherapy and systemic chemotherapy. Surgical implantation of chemotherapy eluting wafers into the resection cavity has been shown to improve length of survival but the current licensed therapy has several drawbacks. This paper investigates in vivo efficacy of a novel drug eluting paste in glioblastoma. METHODS: Poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) self-sintering paste was loaded with the chemotherapeutic agent etoposide and delivered surgically into partially resected tumours in a flank murine glioblastoma xenograft model. RESULTS: Surgical delivery of the paste was successful and practical, with no toxicity or surgical morbidity to the animals. The paste was retained in the tumour cavity, and preliminary results suggest a useful antitumour and antiangiogenic effect, particularly at higher doses. Bioluminescent imaging was not affected significantly by the presence of the paste in the tumour. CONCLUSIONS: Chemotherapy loaded PLGA/PEG paste seems to be a promising technology capable of delivering active drugs into partially resected tumours. The preliminary results of this study suggest efficacy with no toxicity and will lead to larger scale efficacy studies in orthotopic glioblastoma models.

(1)H magnetic resonance spectroscopy in the diagnosis of paediatric low grade brain tumours.

INTRODUCTION: Low grade gliomas are the commonest brain tumours in children but present in a myriad of ways, each with its own treatment challenges. Conventional MRI scans play an important role in their management but have limited ability to identify likely clinical behaviour. The aim of this study is to investigate (1)H magnetic resonance spectroscopy (MRS) as a method for detecting differences between the various low grade gliomas and related tumours in children. PATIENTS AND METHODS: Short echo time single voxel (1)H MRS at 1.5 or 3.0 T was performed prior to treatment on children with low grade brain tumours at two centres and five MR scanners, 69 cases had data which passed quality control. MRS data was processed using LCModel to give mean spectra and metabolite concentrations which were compared using T-tests, ANOVA, Receiver Operator Characteristic curves and logistic regression in SPSS. RESULTS: Significant differences were found in concentrations of key metabolites between glioneuronal and glial tumours (T-test p<0.05) and between most of the individual histological subtypes of low grade gliomas. The discriminatory metabolites identified, such as choline and myoinositol, are known tumour biomarkers. In the set of pilocytic astrocytomas and unbiopsied optic pathway gliomas, significant differences (p<0.05, ANOVA) were found in metabolite profiles of tumours depending on location and patient neurofibromatosis type 1 status. Logistic regression analyses yielded equations which could be used to assess the probability of a tumour being of a specific type. CONCLUSIONS: MRS can detect subtle differences between low grade brain tumours in children and should form part of the clinical assessment of these tumours.

Primary postoperative chemotherapy without radiotherapy for treatment of brain tumours other than ependymoma in children under 3 years: results of the first UKCCSG/SIOP CNS 9204 trial.

BACKGROUND: Radiotherapy is an effective adjuvant treatment for brain tumours arising in very young children, but it has the potential to damage the child's developing nervous system at a crucial time - with a resultant reduction in IQ leading to cognitive impairment, associated endocrinopathy and risk of second malignancy. We aimed to assess the role of a primary chemotherapy strategy in avoiding or delaying radiotherapy in children younger than 3 years with malignant brain tumours other than ependymoma, the results of which have already been published. METHODS: Ninety-seven children were enrolled between March 1993 and July 2003 and, following diagnostic review, comprised: medulloblastoma (n=31), astrocytoma (26), choroid plexus carcinoma [CPC] (15), CNS PNET (11), atypical teratoid/rhabdoid tumours [AT/RT] (6) and ineligible (6). Following maximal surgical resection, chemotherapy was delivered every 14 d for 1 year or until disease progression. Radiotherapy was withheld in the absence of progression. FINDINGS: Over all diagnostic groups the cumulative progression rate was 80.9% at 5 years while the corresponding need-for-radiotherapy rate for progression was 54.6%, but both rates varied by tumour type. There was no clear relationship between chemotherapy dose intensity and outcome. Patients with medulloblastoma presented as a high-risk group, 83.9% having residual disease and/or metastases at diagnosis. For these patients, outcome was related to histology. The 5-year OS for desmoplastic/nodular medulloblastoma was 52.9% (95% confidence interval (CI): 27.6-73.0) and for classic medulloblastoma 33.3% (CI: 4.6-67.6); the 5-year EFS were 35.3% (CI: 14.5-57.0) and 33.3% (CI: 4.6-67.6), respectively. All children with large cell or anaplastic variants of medulloblastoma died within 2 years of diagnosis. The 5-year EFS for non-brainstem high-grade gliomas [HGGs] was 13.0% (CI: 2.2-33.4) and the OS was 30.9% (CI: 11.5-52.8). For CPC the 5-year OS was 26.67% (CI: 8.3-49.6) without RT. This treatment strategy was less effective for AT/RT with 3-year OS of 16.7% (CI: 0.8-51.7) and CNS PNET with 1-year OS of 9.1% (CI: 0.5-33.3). INTERPRETATION: The outcome for very young children with brain tumours is dictated by degree of surgical resection and histological tumour type and underlying biology as an indicator of treatment sensitivity. Overall, the median age at radiotherapy was 3 years and radiotherapy was avoided in 45% of patients. Desmoplastic/nodular sub-type of medulloblastoma has a better prognosis than classic histology, despite traditional adverse clinical features of metastatic disease and incomplete surgical resection. A subgroup with HGG and CPC are long-term survivors without RT. This study highlights the differing therapeutic challenges presented by the malignant brain tumours of early childhood, the importance of surgical approaches and the need to explore individualised brain sparing approaches to the range of malignant brain tumours that present in early childhood.

Relapsed intracranial ependymoma in children in the UK: patterns of relapse, survival and therapeutic outcome.

Relapsed ependymoma in children poses difficult dilemmas in management. Clinico-pathological and treatment data of 108 children with relapsed ependymoma in the United Kingdom (UK) treated between 1985 and 2002 were reviewed to identify prognostic factors affecting survival. The primary site was the most common site of relapse (84%). Overall 25% had metastatic relapse. Surgery at relapse was attempted in only 55%. Radiotherapy was delivered at relapse in 66% infants and 50% of older children were re-irradiated. Overall 5-year survival was 24% and 27% for children less than 3 years of age at initial diagnosis and older children, respectively. Multivariate analysis showed that, for infants, surgery (p=0.01) and radiotherapy (p=0.001) at relapse were independent predictors of survival. For older children regardless of the previous radiotherapy, repeat irradiation was associated with better outcome (p=0.05). Relapse was associated with poor outcome in both age groups. A survival advantage conferred by both radiotherapy and surgery at relapse is independently significant.

Identification and characterisation of childhood cerebellar tumours by in vivo proton MRS.

(1)H MRS has great potential for the clinical investigation of childhood brain tumours, but the low incidence in, and difficulties of performing trials on, children have hampered progress in this area. Most studies have used a long-TE, thus limiting the metabolite information obtained, and multivariate analysis has been largely unexplored. Thirty-five children with untreated cerebellar tumours (18 medulloblastomas, 12 pilocytic astrocytomas and five ependymomas) were investigated using a single-voxel short-TE PRESS sequence on a 1.5 T scanner. Spectra were analysed using LCModel to yield metabolite profiles, and key metabolite assignments were verified by comparison with high-resolution magic-angle-spinning NMR of representative tumour biopsy samples. In addition to univariate metabolite comparisons, the use of multivariate classifiers was investigated. Principal component analysis was used for dimension reduction, and linear discriminant analysis was used for variable selection and classification. A bootstrap cross-validation method suitable for estimating the true performance of classifiers in small datasets was used. The discriminant function coefficients were stable and showed that medulloblastomas were characterised by high taurine, phosphocholine and glutamate and low glutamine, astrocytomas were distinguished by low creatine and high N-acetylaspartate, and ependymomas were differentiated by high myo-inositol and glycerophosphocholine. The same metabolite features were seen in NMR spectra of ex vivo samples. Successful classification was achieved for glial-cell (astrocytoma + ependymoma) versus non-glial-cell (medulloblastoma) tumours, with a bootstrap 0.632 + error, e(B.632+), of 5.3%. For astrocytoma vs medulloblastoma and astrocytoma vs medulloblastoma vs ependymoma classification, the e(B.632+) was 6.9% and 7.1%, respectively. The study showed that (1)H MRS detects key differences in the metabolite profiles for the main types of childhood cerebellar tumours and that discriminant analysis of metabolite profiles is a promising tool for classification. The findings warrant confirmation by larger multi-centre studies.

Short echo time 1 H magnetic resonance spectroscopy of childhood brain tumours.

AIMS: To explore short echo time (30 ms) 1 H magnetic resonance spectroscopy (MRS) in children with brain tumours and determine the contributions to the characterization of these tumours of the metabolites inositol/myoinositol and glutamate/glutamine, which are not visible at long echo times (135 or 270 ms). METHODS: Over a 12-month period 86 single-voxel MRS investigations were performed on 59 children with various brain tumours on a Siemens Symphony 1.5-T Magnetom using point-resolved spectroscopy and echo time of 30 ms. RESULTS: The procedure was well tolerated, and good-quality data were obtained. N-Acetyl aspartate (NAA)/Choline (Cho) and creatine (Cr)/Cho concentration ratios were significantly (p<0.001) lower in tumour (0.95 and 1.63, respectively) compared with non-involved brain (3.68 and 3.98, respectively) in all histological types. Inositol/Myoinositol (Inos)/Cho ratios were significantly (p<0.05) lower in untreated tumours (1.91) than in treated tumours (3.93) and in non-involved brain (3.32). Inos/Cho ratios were high in diffuse pontine gliomas and low in medulloblastomas and supratentorial primitive neuroectodermal tumours (p<0.01). Glutamate/Glutamine (Glut)/Cho ratios were high in grade 1 astrocytomas (6.4) and unbiopsied optic gliomas (9.84) but low in diffuse pontine gliomas (2.44). Lipids and macromolecules were present in most tumours but in low quantities in non-involved brain. CONCLUSION: Good-quality short echo time MRS data can be collected routinely on children with brain tumours. Inos and Glut levels show greater variability between tumour types than NAA, Cho and Cr present at long echo times, providing improved tumour characterization. Inos/Cho levels differ between untreated and treated tumours and may be useful for treatment monitoring.

The development of functional imaging in the diagnosis, management and understanding of childhood brain tumours.

Imaging plays a fundamental role in the management of children with brain tumours. A series of new techniques, commonly grouped under the heading functional imaging, promise to give information on the properties and biological characteristics of tissues thereby adding to the structural information available from current imaging. The EPSRC funded a workshop to bring together clinicians from the UK Children's Cancer Study Group and scientific experts in the field to identify clinical problems in childhood brain tumours that may be addressed by functional imaging and to develop a clinical test bed for applying, evaluating and developing this new technology. The presentations and discussion sessions from the workshop are summarised and a review of the current 'state of the art' for this rapidly developing area provided. A key output of the workshop was agreement on a series of hypotheses which can be tested in carefully designed clinical studies.

Relationship of endocrinopathy to iron chelation status in young patients with thalassaemia major.

Disturbances of growth and development in patients with thalassaemia receiving hypertransfusion programmes are well recognised and are most likely to be due to iron overload. The extent of endocrine dysfunction was investigated in a group of 18 patients thought to have been treated by acceptable modern standards, 11 of whom could be considered as well chelated. Assessment of growth and puberty showed a wide variation in height SD scores with five patients having significantly short stature. Most patients are progressing through puberty normally with the exception of two boys with marked pubertal delay. The most prominent finding was that growth hormone responses to glucagon stimulation were significantly impaired in all of the patients with iron overload. Basal endocrine assessment showed primary hypothyroidism in two patients aged 16.8 and 12.9 years with plasma thyroxine-concentrations of 86 and 59 nmol/l (normal range 65-165 nmol/l) and plasma thyroid stimulating hormone 10.2 and 30.3 mU/l (normal range 0.5-5 mU/l). One patient had diabetes mellitus. These results show that even when ideal management is sought a significant amount of endocrine damage occurs; surveillance of these patients is thus essential.

Perlman and Wiedemann-Beckwith syndromes: two distinct conditions associated with Wilms' tumour.

Though children with Perlman and Wiedemann-Beckwith syndromes have a number of features in common, the two conditions are probably separate entities. The distinction may not always be easy, however, partly because of the extreme rarity of Perlman syndrome, only nine cases of which have been reported so far. We report two siblings, initially diagnosed as having Wiedemann-Beckwith syndrome, in whom the correct diagnosis of Perlman syndrome was made only after an autopsy on the second child. By comparing and contrasting the features of Perlman and Wiedemann-Beckwith syndromes in this report we hope to make it easier to distinguish the two conditions.