A phase II study of preradiotherapy chemotherapy followed by hyperfractionated radiotherapy for newly diagnosed high-risk medulloblastoma/primitive neuroectodermal tumor: a report from the Children's Oncology Group (CCG 9931).

PURPOSE: To verify feasibility and monitor progression-free survival and overall survival in children with high-risk medulloblastoma and noncerebellar primitive neuroectodermal tumors (PNETs) treated in a Phase II study with preradiotherapy chemotherapy (CHT) followed by high-dose, hyperfractionated craniospinal radiotherapy (CSRT). METHODS AND MATERIALS: Eligibility criteria included age >3 years at diagnosis, medulloblastoma with either high M stage and/or >1.5 cm(2) postoperative residual disease, and all patients with noncerebellar PNET. Treatment was initiated with five alternating monthly cycles of CHT (A [cisplatin, cyclophosphamide, etoposide, and vincristine], B [carboplatin and etoposide], A, B, and A) followed by hyperfractionated CSRT (40 Gy) with a boost to the primary tumor (72 Gy) given in twice-daily 1-Gy fractions. RESULTS: The valid study group consisted of 124 patients whose median age at diagnosis was 7.8 years. Eighty-four patients (68%) completed the entire protocol according to study guidelines (within 9 months), and the median time to complete CSRT was 1.6 months. Major reasons for failure to complete CHT included progressive disease (17%) and toxic death (2.4%). The 5-year progression-free survival and overall survival rates were 43% +/- 5% and 52% +/- 5%, respectively. No significant differences were detected in subset analysis related to response to CHT, site of primary tumor, postoperative residual disease, or M stage. CONCLUSIONS: The feasibility of this intensive multimodality protocol was confirmed, and response to pre-RT CHT did not impact on survival. Survival data from this protocol can not be compared with data from other studies, given the protocol design.

Patterns of treatment failure in infants with primitive neuroectodermal tumors who were treated on CCG-921: a phase III combined modality study.

PURPOSE: To analyze patterns of treatment failure in infants with primitive neuroectodermal tumors (PNETs) who were treated primarily with chemotherapy in a large multi-institutional study. MATERIALS AND METHODS: Sixty-five prospectively staged patients with PNET confirmed by central pathology review, who were 18 months or younger were treated on Children's Cancer Group Study 921 (CCG-921) primarily with chemotherapy. Forty-six patients had posterior fossa (PF) primary tumors and 19 patients had supratentorial (ST) primaries. Patterns of sites of initial treatment failure were analyzed and compared to failure patterns of 180 older children who had PF-PNETs, and 44 older children with ST-PNETs who were treated on the same protocol. RESULTS: The entire cohort of younger patients fared much worse than those older than 18 months. Cumulative 5-year relapse incidence (+/-SE) for younger patients with PF-PNETs was 64.5 +/- 8.9% for patients without metastases (M0) compared to 71.4 +/- 13.4% for patients with metastases (M+). The cumulative 5-year relapse incidences for younger patients with ST-PNETs were 64.3 +/- 13.7% for M0 patients compared to 100 +/- 33.3% for M+ patients. Relapses in these patients occurred within 2 years. The overall treatment failure rate was significantly higher for younger compared to older patients with PF-PNET and ST-PNET. There was no statistically significant difference in relapse patterns between patients with PF primary tumors and ST primaries when stratified by stage. There was no statistically significant difference in relapse patterns between M0 and M+ patients. All patients had a high risk of recurrence at primary tumor site. Younger patients who had PF primary tumors without metastasis at presentation were significantly more likely to relapse in PF than older patients. Younger patients were at significant risk of relapse in the spine, but none had it as the sole site of first relapse. CONCLUSIONS: Despite aggressive chemotherapy, younger children with PNETs have high rates of treatment failure and fare worse than high-risk, older patients with PF-PNETs, indicating the need to maximize local, regional, and systemic therapies.

Recurrent central nervous system medulloepithelioma: response and outcome following marrow-ablative chemotherapy with stem cell rescue.

Medulloepithelioma is a rare primitive neuroectodermal tumor of the central nervous system usually developing in childhood, displaying highly malignant behavior, with early progression or recurrence. Once a recurrence develops, death reportedly follows with invariable rapidity. The purpose of this study was to evaluate the efficacy of high-dose, marrow-ablative chemotherapy with autologous hemopoietic stem cell rescue in the treatment of recurrent central nervous system medulloepithelioma. Three young children with recurrent central nervous system medulloepithelioma received high-dose marrow-ablative chemotherapy with thiotepa and etoposide either alone (one patient) or with the addition of carboplatin (two patients). This was followed by irradiation only in one patient. One child with residual radiographic tumor at the time of treatment could be evaluated for response and showed complete resolution of leptomeningeal disease after receiving marrow-ablative chemotherapy. Two children developed tumor recurrence at 2.0 and 5.5 months after receiving marrow-ablative chemotherapy. The third child continues free of tumor beyond 12 years from treatment. The authors' experience with marrow-ablative chemotherapy and autologous hemopoietic stem cell rescue suggests that this treatment strategy might be beneficially incorporated into the initial treatment approach for young children with medulloepithelioma.

INI1 protein expression distinguishes atypical teratoid/rhabdoid tumor from choroid plexus carcinoma.

Central nervous system atypical teratoid/rhabdoid tumor (AT/RT) and choroid plexus carcinoma (CPC) are rare, highly malignant tumors that predominantly arise in infants and young children. Overlapping clinical, histologic, ultrastructural, or immunophenotypic features may obscure the diagnosis in some cases. AT/RT is characterized by deletions and/or mutations of the INI1 tumor-suppressor gene on chromosome band 22q11.2. We have recently developed an INI1 immunohistochemical staining assay. Negative staining of tumor cells resulting from inactivation of the INI1 gene is a consistent feature of AT/RT. Mutations of INI1 in some CPCs have been reported. The purpose of the present study was to determine if immunohistochemical staining with an INI1 antibody would provide a sensitive means of distinguishing between CPC and AT/RT. We examined 28 tumors with a submitted diagnosis of CPC. Twenty-one CPCs showed retained expression of INI1 and seven tumors showed loss of INI1 expression. Cytogenetic, FISH, and/or INI1 mutation results were also available for 13 tumors. In three of the seven cases, monosomy 22 was the only cytogenetic abnormality, suggestive of AT/RT. However, monosomy 22 was also identified in 3 tumors with complex karyotypes that retained INI1 expression. The 7 tumors that were immunonegative for INI1 had features that were consistent with AT/RT. Immunostaining for INI1 protein is retained in the majority of CPC and is lost in AT/RT. This expression pattern seems to better define the 2 groups of tumors than does light or electron microscopy, routine immunohistochemistry, or cytogenetic analysis alone.

Losses of chromosomes 1p and 19q are rare in pediatric oligodendrogliomas.

Pediatric oligodendrogliomas are rare neoplasms and have not been characterized extensively either pathologically or genetically. Given the recent interest in the significance of chromosomal losses in predicting the clinical course and in establishing uniform diagnoses of adult oligodendrogliomas, we reviewed the pathological and clinical features of a series of pediatric oligodendrogliomas and determined their 1p and 19q status using fluorescence in situ hybridization. Of 19 tumors originally diagnosed as oligodendroglioma, 7 were oligodendroglioma, 3 were anaplastic oligodendroglioma, 3 were oligoastrocytoma, and 6 were reclassified. Only one tumor, an anaplastic oligodendroglioma, had 1p loss; none had 19q loss. The single patient whose tumor had 1p loss did not have a particularly favorable clinical course. These results suggest that pediatric oligodendrogliomas arise by molecular alterations distinct from adult oligodendrogliomas, and such molecular alterations do not hold immediate promise as an adjunct to the diagnosis of pediatric oligodendrogliomas.

Patterns of failure in supratentorial primitive neuroectodermal tumors treated in Children's Cancer Group Study 921, a phase III combined modality study.

PURPOSE: To analyze the patterns of failure in patients with supratentorial primitive neuroectodermal tumors (ST-PNETs) treated with combined modality therapy in a large, randomized, multi-institutional study. METHODS AND MATERIALS: A total of 44 prospectively staged patients with ST-PNET confirmed by central pathology review were treated in the Children's Cancer Group Study 921, which compared two chemoradiotherapy regimens. The patterns of initial sites of failure were analyzed. These were compared with the failure patterns of 188 children with posterior fossa (PF) PNETs treated in the same protocol. RESULTS: The major determinant for progression-free survival was the initial metastatic stage. The 3-year progression-free survival for M0 patients was 53% +/- 8.5% compared with 14% +/- 9.4% for M+ patients. The cumulative 5-year relapse incidence was 71.4% +/- 21% for M+ patients compared with 47.5% +/- 8.6% for M0 patients. The overall failure rate for both M0 and M+ ST-PNETs was greater than that for PF-PNETs (47.5% +/- 8.6% vs. 29.3% +/- 4.7% for M0 and 71.4% +/- 21% vs. 48.4% +/- 5.5% for M+). Failure at the primary site, either as the sole site or as a component of initial failure, was also seen more frequently in ST-PNETs than in PF-PNETs. For M0 patients, the 5-year local failure rate as a component of initial failure was 42.0% +/- 8.5% for ST-PNETs compared with 17.7% +/- 3.9% for PF-PNETs. For patients with primary tumors either in the ST or PF, the 5-year spinal axis failure rate as a component of initial failure was not significantly different statistically when compared by M stage. For M+ patients, the 5-year spinal axis failure rate as a component of initial failure was 42.9% +/- 22.8% for ST-PNETs and 34.6% +/- 5.2% for PF-PNETs. CONCLUSION: Despite aggressive combined modality therapy, ST-PNETs had high rates of failure, with M+ patients faring especially poorly. Both local and spinal failure rates remained high, indicating the need to maximize both local and regional/systemic therapies. Overall, these patients fared worse than those with high-risk PF-PNETs in terms of progression-free survival and failure rates.

Near complete surgical resection predicts a favorable outcome in pediatric patients with nonbrainstem, malignant gliomas: results from a single center in the magnetic resonance imaging era.

BACKGROUND: Because few reports on outcome in patients with pediatric malignant gliomas during the magnetic resonance imaging era were available, the authors studied the outcomes of children with these tumors at their institution. METHODS: The medical records of 39 patients with nonbrainstem, malignant gliomas who were treated at the Hospital of the University of Pennsylvania/Children's Hospital of Philadelphia between February 1, 1989 and December 31, 2000 were reviewed retrospectively. Magnetic resonance imaging was used to assess tumors at presentation and at follow-up. Progression-free survival (PFS) and overall survival (OS) were determined using the Kaplan-Meier method. Univariate and multivariate analyses were performed using a Cox proportional hazards model. RESULTS: The median follow-up for the 14 surviving patients was 47.6 months. The median PFS for all patients was 12.2 months, and the median OS for all patients was 21.3 months. The extent of surgery was the strongest prognostic factor for predicting outcomes in these patients, with a median survival of 122.2 months in patients who underwent macroscopic total resection compared with 14.1 months in patients who had significant residual disease after surgery. In univariate analyses, other than the extent of surgery, only the absence of visual symptoms at diagnosis significantly predicted improved OS. Local control was improved for patients who underwent better resection and had smaller tumors. In multivariate analyses, although the extent of surgery continued to predict outcomes significantly, histologic grade, which was not significant in the univariate analysis, also was significant. CONCLUSIONS: Children with malignant gliomas appeared to fare better than their adult counterparts. Because the extent of resection was one of the strongest predictors of outcome, the authors concluded that the optimal therapy for these patients would include the maximal possible resection.

Central nervous system atypical teratoid/rhabdoid tumor: results of therapy in children enrolled in a registry.

PURPOSE: Atypical teratoid/rhabdoid tumor (AT/RT) of the CNS is an extremely rare and aggressive tumor of early childhood. The poor outcome with conventional infant brain tumor therapy has resulted in a lack of clear treatment guidelines. A registry has been established to create an outcomes database and to facilitate biology studies for this tumor. MATERIALS AND METHODS: A standardized data sheet was provided to treating physicians listing the reports that were to be sent to the registry for abstraction. Follow-up information was sought twice yearly. RESULTS: Information was complete for 42 patients. Median age at diagnosis was 24 months. Nine patients (21%) had disseminated disease at diagnosis. Sixteen tumors were infratentorial; 26 were supratentorial. Twenty patients (48%) received a primary complete resection. Primary therapy included chemotherapy in all patients, radiotherapy in 13 patients (31%), stem-cell rescue in 13 patients (31%), and intrathecal chemotherapy in 16 patients (38%). Recurrent or progressive disease was reported in nine and 19 patients, respectively. Twenty-seven patients (64%) are dead of disease (3 to 62 months from diagnosis) and one patient died of toxicity. Fourteen patients (33%) show no evidence of disease (9.5 to 96 months from diagnosis). The median survival is 16.75 months and the median event-free survival is 10 months. CONCLUSION: Aggressive therapy has prolonged the natural history in a subset of children. Prospective multi-institutional and national clinical trials designed specifically for AT/RT are needed. Enrollment onto the AT/RT registry should be continued.

Technical communication: rationale and technique for examination of nervous system in suspected infant victims of abuse.

Most victims of fatal child abuse are under the age of 2 years and have a fairly typical pattern of injuries that involve the brain and spinal cord. Documenting these injuries in a systematic fashion is of paramount importance in establishing the cause and manner of death. Although the importance of recognizing these injuries is widely understood, there are few guidelines for the optimal examination of the central nervous system to document these changes. A standard procedure for postmortem dissection of the brain and spinal cord that preserves the anatomy of the cervicomedullary junction is outlined. Changes in the cervicomedullary junction and spinal cord are an underappreciated marker for shaking injury in children. This technique, along with examination of the eyes and optic nerves, will optimally identify the injuries associated with shaking injuries. A standard series of histologic sections are also outlined to document the corresponding microscopic changes.

Immunohistochemical analysis of hSNF5/INI1 in pediatric CNS neoplasms.

Atypical teratoid/rhabdoid tumor (AT/RT) may be misdiagnosed as primitive neuroectodermal tumor/medulloblastoma (PNET) and occasionally as other tumors. Molecular genetic analysis of AT/RT demonstrates deletion and mutation of the hSNF5/INI1 gene in most cases, with decreased or absent expression at the RNA or protein level. Immunohistochemistry with an antibody to INI1 was performed to determine whether this would be a sensitive and specific means of assessing INI1 loss in pediatric brain tumors. Fifty-three tumors consisting of 20 AT/RTs, 10 PNETs, and 23 other central nervous system tumors were examined. No nuclear staining was found in all 20 AT/RTs. Most other central nervous system tumors demonstrated nuclear staining. Eight cases in which classification as AT/RT or PNET was difficult were also examined. Seven cases had no chromosome 22 deletion or INI1 mutation; INI1 antibody showed nuclear staining in these cases. One case was a recurrent tumor with features consistent with an AT/RT. INI1 immunostaining was negative in this case, and a mutation in INI1 was subsequently identified. Immunohistochemical staining with an INI1 antibody correlates with molecular findings in AT/RT and may be useful in confirming the histologic diagnosis. INI1 immunostaining may have particular utility in the analysis of tumors with indeterminate histologic features or atypical immunophenotypic profiles.

Double immunolabeling of central nervous system atypical teratoid/rhabdoid tumors.

The central nervous system atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant tumor with a heterogeneous immunohistochemical profile and with some morphologic similarity to central nervous system primitive neuroectodermal tumors (PNET). Although several studies have investigated double immunolabeling in PNET, we are aware of no studies of double labeling of ATRT. A total of 10 ATRT from surgical and consultation materials at the Children's Hospital of Philadelphia were selected and stained for a variety of antigens using indirect immunofluorescence to detect single and double labeling. Most tumor cells showed only single labeling; rare cells showed double labeling as follows: 70% of tumors coexpressed (VIM) and glial fibrillary acidic protein (GFAP), 30% smooth muscle actin and GFAP, 20% epithelial membrane antigen (EMA) and VIM, 20% EMA/GFAP, and 20% EMA/SMA. These results are discussed in view of current debates over the histogenesis of CNS PNET and ATRT, and in reference to the classification of rhabdoid tumors as an entity or phenotype.

Prognostic limitations of the Daumas-Duport grading scheme in infratentorial neuroglial tumors in children.

The Daumas-Duport grading scheme (DDGS) utilizes four histologic features in an additive method (grade 1 if none present, grade 2 if only one is present, etc.). Its efficacy in achieving prognostically homogeneous groups of childhood infratentorial neuroglial tumors and its concordance with World Health Organization (WHO) diagnoses has not been evaluated. We investigated these questions using the Childhood Brain Tumor Consortium (CBTC) database of 1241 neuroglial tumors limited to the infratentorial compartment. We calculated survival function estimates for various DDGS grades as well as the histologic features within each grade. The feature of endothelial prominence improved survival expectation, whereas the remaining three features of nuclear atypia, mitoses, and necrosis were associated with worsened survival. Survival estimates for tumors with DDGS grades 2 and 3 did not differ. Some grades contained feature subsets with significantly different survival distributions. The survival distributions of DDGS grade 1, DDGS grade 2 with only endothelial prominence, and DDGS grade 3 with nuclear atypia and endothelial prominence were not significantly different. DDGS grade within WHO diagnoses had no significant effect on survival expectation. We conclude that grading by summation of only four histologic features, as in the DDGS, is inappropriate for assessment of childhood neuroglial tumors. A classification scheme considering the complete histologic content is more likely to provide clinically useful diagnoses. Such a scheme, based on the CBTC database is available. This scheme uses 26 histologic features identified as reliable in read-reread studies.

Craniospinal radiation in the treatment of biopsy-proven intracranial germinomas: twenty-five years' experience in a single center.

PURPOSE: The optimal treatment for intracranial germinomas remains controversial. We report on our 25-year experience using craniospinal irradiation (CSI) for this disease. METHODS AND MATERIALS: Between September 1976 and May 2001, 39 patients with biopsy-proven intracranial germinomas seen at the Children's Hospital of Philadelphia/Hospital of the University of Pennsylvania received CSI. Thirteen of 36 patients (36%) had evidence of spinal dissemination. Median doses to the whole brain, primary site, and spine were 36 Gy (range, 18-44.2 Gy), 50.4 Gy (range, 44-55.8 Gy), and 30.6 Gy (range, 18-40 Gy), respectively. RESULTS: With a median follow-up of 7.1 years (range: 1.5-20.2 years), there have been no documented relapses. This includes 5 patients without spinal dissemination who received 18-19.8 Gy to the craniospinal axis; for these patients, the median length of follow-up was 5.5 years (range, 1.3-6.8 years). One patient, who had no evidence of disease 12.9 years after CSI, died of unknown causes 4 months later. CONCLUSIONS: Our treatment of intracranial germinomas with CSI has yielded outstanding results with no known relapses during a long follow-up period. These results must be considered when evaluating other approaches, such as chemotherapy only or local field irradiation.

Surgery with or without radiation therapy in the management of craniopharyngiomas in children and young adults.

PURPOSE: The optimal management of craniopharyngiomas remains controversial, especially in children and young adults. This study reports a single institution's experience with such patients. METHODS AND MATERIALS: Between 1974 and 2001, 76 patients were treated for craniopharyngioma at the Children's Hospital of Philadelphia and the Hospital of University of Pennsylvania (HUP). Of these, 75 patients (97%) were evaluable with long-term follow-up. Although all patients underwent attempted gross total resection, 27 had documentation of less than total resection with 18 of these patients receiving immediate postoperative radiotherapy (RT). An additional 22 patients received RT at HUP after failing surgery alone. RESULTS: Median follow-up for all patients was 7.6 years. The 10-year actuarial overall survival, relapse-free survival, and local control (LC) rates for all patients were 85%, 48%, and 53%, respectively. When comparing the 57 patients treated with surgery alone to the 18 treated with subtotal resection (STR) followed by RT, a significant difference in LC rates at 10 years (42% vs. 84%, respectively; p = 0.004) was noted. However, no statistically significant difference in overall survival was found between the two groups, because RT was highly effective as salvage therapy. Twenty-two patients at HUP treated with RT after relapse had a 10-year ultimate LC rate comparable to that of patients who received RT immediately after STR. CONCLUSION: RT given either immediately after STR or at relapse is effective in controlling craniopharyngiomas.

Loss of caspase-8 protein expression correlates with unfavorable survival outcome in childhood medulloblastoma.

PURPOSE: Escaping apoptosis is a hallmark of cancer. In medulloblastoma (MB) cell lines, resistance to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis was recently shown to correlate with loss of caspase-8 mRNA expression, because of aberrant gene methylation (M. A. Grotzer et al., Oncogene, 19: 4604-4610, 2000). Loss of caspase-8 mRNA expression has been demonstrated in a subset of primary MB (T. J. Zuzak et al., Eur. J. Cancer, 38: 83-91, 2002). In this study, we analyzed primary MB samples to test whether loss of caspases correlates with survival outcome. EXPERIMENTAL DESIGN: We used immunohistochemistry to analyze the protein expression of the key initiator caspase-8 and caspase-9 in paraffin-embedded tumor samples from 77 well characterized MB patients and compared the expression levels of caspase-8 and caspase-9 with apoptosis indices, clinical variables, and survival outcomes. RESULTS: Weak expression of caspase-8 and caspase-9 was found in 16 and 24% of the MB samples evaluated, respectively. Weak expression of caspase-8 was an independent significant prognostic factor for unfavorable progression-free survival outcome and was more predictive than standard clinical factors. In contrast, caspase-9 expression was not a prognostic factor. Treatment of caspase-8-deficient MB cells with IFN-gamma resulted in dose-dependent restoration of caspase-8 mRNA and protein expression and restoration of tumor necrosis factor-related apoptosis-inducing ligand sensitivity. CONCLUSIONS: Loss of initiator caspase-8 is associated with an unfavorable survival outcome. Restoration of caspase-8 (e.g., by treatment with IFN-gamma) might, therefore, represent a novel experimental therapy in childhood MB.

In vivo pyruvate detected by MR spectroscopy in neonatal pyruvate dehydrogenase deficiency.

We present a unique finding of an elevated level of pyruvate at 2.37 ppm revealed by in vivo MR spectroscopy of a female neonate. Low fibroblast pyruvate dehydrogenase (PDH) complex activity subsequently confirmed a diagnosis of PDH deficiency. Abnormalities of brain development consistent with PDH deficiency were also evident on fetal and postnatal MR images. To our knowledge, this is the first report of pyruvate being shown in vivo in a child and the first report of MR spectroscopy aiding in the diagnosis of inborn error in pyruvate metabolism before confirmation by conventional enzymatic testing. This finding has potential implications for earlier diagnosis in patients with defects in mitochondrial metabolism.

Expression of alpha-, beta-, and gamma-synuclein in glial tumors and medulloblastomas.

alpha-, beta- and gamma-synuclein are highly homologous proteins that are found predominantly in neurons. Abnormal accumulation of synucleins has been associated with diseases of the central nervous system particularly Parkinson's disease. Immunoreactivity of alpha-synuclein is demonstrated in brain tumors with neuronal differentiation and in schwannomas, whereas gamma-synuclein has been demonstrated in breast and ovarian carcinomas. The immunoreactivity of synucleins has not been described in glial tumors. Immunoreactivity of synucleins in glial cells in culture and in pathological conditions, however, suggests that synucleins may be expressed by glial tumors. We studied the expression of alpha-, beta-, and gamma-synuclein in 84 human brain tumors (24 ependymomas, 31 astrocytomas, 8 oligodendrogliomas, and 21 medulloblastomas) by immunohistochemistry. Our study demonstrates immunoreactivity for gamma-synuclein in high-grade glial tumors; immunoreactivity is found in all anaplastic ependymomas but in only 33% of ependymomas and 16% of myxopapillary ependymomas. Immunoreactivity for gamma-synuclein is noted in 63% of glioblastomas but not in other astrocytic tumors. Of medulloblastomas, 76% have immunoreactivity for either alpha- or beta-synuclein or both; no immunoreactivity for gamma-synuclein is seen in medulloblastomas.

Correction of hindbrain herniation and anatomy of the vermis after in utero repair of myelomeningocele in sheep.

BACKGROUND/PURPOSE: In utero repair of myelomeningocele (MMC) in humans spares distal neurologic function, reverses the hindbrain herniation component of the Arnold-Chiari II malformation (ACM), and reduces the rate of postnatal shunt placement. The authors hypothesized that extravasation of cerebrospinal fluid (CSF) from the lumbar spinal cord results in herniation. This hypothesis was tested by assessing the impact of a spinal cord myelotomy on hindbrain anatomy in fetal sheep. METHODS: A MMC lesion was created surgically in 34 fetal sheep at 75 days' gestation by excision of the L1-L5 lamina, the exposed dura, and surrounding tissues. A lumbar level myelotomy was performed in 28 of the 34 fetuses to open the central canal of the spinal cord to enhance egress of CSF through the MMC defect and potentially induce hindbrain herniation. At 102 days' gestation, a repair of the MMC lesion was performed in 14 fetuses with a myelotomy. Fetuses underwent autopsy at 102, 114, 120, or 140 days' gestation. Control animals underwent 2 unrelated fetal surgical procedures at approximately 70 and 110 days' gestation. The incidence of hindbrain herniation, ventricular size, biparietal diameter, brain weight, and brain anatomy were compared between the different animal groups. RESULTS: After MMC creation, significant cerebellar tonsillar herniation was observed in 85% of fetuses that underwent creation of a myelotomy; none of the lambs without a myelotomy (n = 6) had hindbrain herniation. At autopsy, cerebellar tonsillar herniation was present at the time of MMC repair (102 days' gestation), 2 weeks after MMC repair, but was reversed 3 weeks post-MMC repair. At birth, tonsillar herniation was absent, and hindbrain anatomy was restored in 88% of the fetuses with a myelotomy that underwent fetal MMC repair. No significant differences in brain weight and ventricular size was observed between animals with and without MMC repair. CONCLUSIONS: Adding a myelotomy to the sheep model of MMC leads to hindbrain herniation that is similar to that observed in the human ACM. These experiments support the hypothesis that leakage of CSF through the exposed central canal alters the normal CSF hydrodynamics, resulting in cerebellar tonsillar herniation. Fetal MMC repair reverses hindbrain herniation and restores gross anatomy of the vermis.

Alterations of the hSNF5/INI1 gene in central nervous system atypical teratoid/rhabdoid tumors and renal and extrarenal rhabdoid tumors.

Germ-line and acquired mutations of the hSNF5/INI1 tumor suppressor gene have been reported in central nervous system (CNS), renal, and soft-tissue rhabdoid tumors. The present study was designed to compare the types of INI1 alterations among tumors from diverse anatomical sites and identify mutation hot spots. Fluorescence in situ hybridization and PCR-based microsatellite, heteroduplex, and sequence analysis were used to characterize chromosome 22 deletions and INI1 mutations among 100 primary rhabdoid tumors. Deletions and/or mutations of INI1 were detected in 75 patients, including 42 children with atypical teratoid/rhabdoid tumors of the brain or spinal cord and 6 children with a brain and a renal or soft-tissue tumor. Nineteen tumors arose in the kidney (in one child, bilaterally) and eight tumors were extra-renal. Homozygous deletions detected by fluorescence in situ hybridization were most often seen in CNS and extra-renal rhabdoid tumors, whereas truncating mutations were detected in a high percentage of CNS and kidney tumors. The highest frequencies of INI1 mutations for kidney tumors were seen in exons 2, 6, and 7, compared with exons 5 and 9 for CNS tumors. Two potential hot-spot mutations for CNS atypical teratoid/rhabdoid tumors were noted, including a C-to-T transition in codon 201 in exon 5 and a cytosine deletion in exon 9. Germ-line mutations were noted in 10 children, including 4 patients with two primary tumors. The majority of rhabdoid tumors from all sites contained deletions and/or mutations of the INI1 gene. Specific mutations were nonrandomly associated with anatomical site.