Abstract 4361: Retinoblastoma (RB) genomic progression analysis using Tissue Microarrays (TMA) comprising 121 RB patient tumors

Retinoblastoma is the second most common childhood intraocular malignancy and development of the tumor is initiated by bi-allelic loss of the RB1 gene. Bi-allelic RB1 loss may not always directly lead to malignant retinoblastoma, rather other genetic changes are likely involved. Subsequent mutational events, specifically gain and loss of chromosomal regions harboring key oncogenes and tumor suppressor genes, appear to underlie the progression of precursor lesions such as retinoma to retinoblastoma. Research thus far has implicated several cytogenetic aberrations in this sequence of molecular events, the two most recurrent and notable being the augmented copy number status of KIF14 and MDM4 on 1q and of DEK and E2F3 on 6p. A small subset of retinoblastoma also exhibits high-level amplification of the MYCN gene on chromosome 2p. KIF14, MDM4, DEK, E2F3 and MYCN have been widely characterized as oncogenes in a variety of cancers. The functional roles of the proteins encoded by these genes would also confer tumor cells manifesting these genomic changes with a selective survival and proliferative advantage. Our project is testing the hypothesis that 1q and 6p gain and 2p amplification - defined by extra copies of KIF14 and MDM4, DEK and E2F3 and MYCN respectively - are associated with clinical parameters of progression. The study comprises formalin-fixed paraffin-embedded fluorescence in situ hybridization (FFPE-FISH) analysis of pre-constructed tissue microarrays comprising 121 patient tumours, in order to determine the genomic copy number status of the five aforementioned genes. Results show 1q gain (3-10 copies) in 102/121 (84%), 6p gain in 115/121 (95%), MYCN gain in 14/121 (12%) and MYCN amplification (>10 copies) in 16/121 (14%) patient tumors. Assessment of potential correlations between the copy number status of these genes and clinical variables of disease progression include patient age, pathology at the time of diagnosis, optic nerve invasion, choroid involvement, laterality of the disease, number of tumor foci present at the time of diagnosis and histopathological parameters. To our knowledge, there has been no recent study associating genomic change of these five genes with clinical parameters of progression in a sample size of statistical significance. The large cohort and consequent statistical power of our results will facilitate a better understanding of the biological role of these genes in the progression from retinoma to retinoblastoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4361.

Ventriculocystostomy and endoscopic third ventriculostomy/shunt placement in the management of hydrocephalus secondary to giant retrocerebellar cysts in infancy

Hydrocephalus secondary to giant retrocerebellar cysts in infancy is a challenging condition and many treatment options exist. The authors report on 3 consecutive cases involving infants under the age of 6 months treated successfully with ventriculocystostomy in combination with direct hydrocephalus treatment (endoscopic third ventriculostomy or shunt placement). They describe the operative procedure, the surgical morbidity, and outcome in each case and review the literature regarding surgical approaches to this condition.

Retinoblastoma CSF metastasis cured by multimodality chemotherapy without radiation

OBJECTIVE

Cerebrospinal fluid (CSF) metastasis is the most difficult type of retinoblastoma metastasis to cure, even with bone marrow transplant. Most metastatic retinoblastoma cells express P-glycoprotein causing multidrug resistance (MDR). P-glycoprotein-rich blood vessels form blood-brain and blood-eye barriers, inhibit drug entry into central nervous system (CNS) and eyes. High-dose craniospinal radiation is too morbid for treatment of young children. To cure CSF metastasis without radiation, we designed an intensive multimodality chemotherapy regimen.

METHOD

After left eye enucleation, a 4-month-old boy with bilateral International Intraocular Retinoblastoma Classification Group E eyes and CSF metastasis was treated with 7-cycle high-dose carboplatin and etoposide, standard-dose vincristine, and high-dose/short-infusion cyclosporine to inhibit P-glycoprotein. Intraventricular drugs, non-substrate of P-glycoprotein (cytarabine), or less susceptible to MDR (topotecan), contributed to treatment of the metastasis. On achieving complete response, he was consolidated with supralethal-dosage carboplatin, etoposide, and cyclophosphamide, and his bone marrow rescued with autologous cord blood stem cells.

RESULTS

Following 1-cycle systemic chemotherapy and 2-dose intraventricular chemotherapy, the CSF metastasis cleared. The right eye tumor regressed completely. The patient remains in remission 8.3 years after diagnosis and 7.8 years post-transplant.

CONCLUSION

Intensive multimodality chemotherapy can cure CSF metastasis in retinoblastoma without incurring extreme morbidity from craniospinal radiation.

Identification of a novel mutation in GYS1 (muscle-specific glycogen synthase) resulting in sudden cardiac death, that is diagnosable from skin fibroblasts

We report here the identification of a patient with muscle-specific glycogen synthase deficiency. The 8-year-old patient showed no prior signs of distress before collapsing during a bout of exercise, resulting in death. Initial post-mortem analysis of tissues suggested death was due to metabolic complications of mitochondrial myopathy, but upon further examination it was found that the anomalies were indicative of mitochondrial proliferation and oxidative compensation. A homozygous two base pair deletion was identified in exon 2 of GYS1, and the parents and sibling were confirmed as heterozygous carriers of the deletion. This case highlights the importance of differentiating between mitochondrial compensatory phenomena and true mitochondrial disease, and suggests that GYS1 deficiency could be a common cause of sudden cardiac death in children. Children with abnormal cardiac responses to increased workloads as well as those with defined myocardial disease should therefore be tested for GYS1 deficiency.

Changing ictal-onset EEG patterns in children with cortical dysplasia

PURPOSE

Cortical dysplasia (CD) is intrinsically epileptogenic. We hypothesize that CDs clinically emerging in the early developing brain tend to extend into multifocal or larger epileptic networks to pronounce intractability in contrast to CDs which clinically emerge at a later age.

METHODS

We evaluated the spatial and temporal profiles of ictal-onset EEG patterns in children with histopathologically confirmed CD. We designated Group A as children with changing ictal-onset EEG patterns over time, and Group B without change. We compared seizure profiles, consecutive scalp video-EEGs (VEEGs), MRI, MEG, and surgical outcomes.

RESULTS

We found 14 children consisting of 10 Group A patients (7 girls) and 4 Group B patients (all boys). Eight (80%) Group A patients had their seizure onset <5 years while all Group B patients had seizure onset >or=5 years (p<.05). Changes of ictal onset EEG pattern in Group A consisted of bilateral (4 patients), extending (2); extending and bilateral (2); and generalized (2). We saw MRI lesions (6) and single clustered MEG spike sources (MEGSSs) in (5). Six patients underwent surgery before 15 years of age, and 4 of them attained seizure freedom. All 4 Group B patients had MRI lesions and single clustered MEGSSs. Three patients underwent surgery after 15 years of age. All 4 patients attained seizure freedom.

CONCLUSION

Ictal-onset EEG patterns change over time in children with early seizure onset and intractable epilepsy caused by CD. Younger epileptic children with CD more frequently have multifocal epileptogenic foci or larger epileptogenic foci. Early resection of CD, guided by MRI, MEG, and intracranial video EEG, resulted in seizure freedom despite changes in ictal-onset EEG patterns.

High-grade primary diffuse leptomeningeal gliomatosis in a child with neurofibromatosis Type 1

The authors report on a child with known neurofibromatosis Type 1 who developed high-grade diffuse leptomeningeal gliomatosis, without a known primary glioma. To the authors' knowledge, this is the first report of the coexistence of these conditions in a child.

Trilateral retinoblastoma with pituitary-hypothalamic dysfunction

Trilateral retinoblastoma is characterized by retinal tumors in one or both eyes, as well as tumors of the pineal gland or parasellar region of the brain. Here we describe a 4-month-old girl, presenting with pituitary dysfunction, hypothalamic overgrowth syndrome and central blindness, in addition to suprasellar and bilateral retinal tumors. Biopsy of the suprasellar tumor confirmed the diagnosis of trilateral retinoblastoma. After biopsy, cerebrospinal fluid (CSF) metastasis was discovered. Overgrowth persisted, but blindness and pituitary dysfunction resolved when the suprasellar tumor and CSF metastasis responded to cyclosporine-modulated systemic chemotherapy with intraventricular chemotherapy, consolidated with marrow-ablative chemotherapy and stem cell rescue of the bone marrow. Twenty months after diagnosis and 12 months after transplant, an unusual pattern of tumor recurrence was observed along the catheter of the Ommaya reservoir used for delivering intraventricular chemotherapy, which was also at the site of the previous suprasellar needle biopsy. Salvage therapy consisted of resection, stereotactic radiation, and further systemic and intraventricular chemotherapy. At 25 months after diagnosis, the patient was developing well and seeing better. However, she died 32 months after diagnosis despite the salvage therapy. This case highlights the possibility of tumor dissemination after needle biopsy of a suprasellar tumor. Biopsy may be avoided if a characteristic clinicoradiological picture of trilateral retinoblastoma is recognized. We recommend that if a pineal or suprasellar tumor is observed in a child, the eyes should be examined for retinoblastoma, thereby avoiding biopsies of the intracranial tumor, which may track difficult-to-treat tumor cells through the brain, and disseminate tumor cells into the CSF.

Rhombencephalosynapsis: prenatal imaging and autopsy findings

OBJECTIVES

Rhombencephalosynapsis is a rare, but increasingly recognized, brain malformation characterized by congenital fusion of the cerebellar hemispheres and absence of the vermis. Rhombencephalosynapsis is associated with significant developmental delay, seizures and involuntary head movements. We report four cases, with correlation of prenatal and postnatal imaging and autopsy findings.

METHODS

Over a 2-year period, four cases of rhombencephalosynapsis were diagnosed in the perinatal period, three in one center and one in another center. The clinical cases were reviewed, and correlation was made between the prenatal and postnatal imaging and autopsy findings where available.

RESULTS

All cases presented initially with ventriculomegaly on prenatal ultrasound examination. Subsequent magnetic resonance imaging (MRI) established the diagnosis in two cases and postnatal MRI established the diagnosis in a further two cases. Autopsy was available and confirmed the diagnosis in two cases. In one case the pregnancy was terminated, two infants died in the neonatal period and one died in infancy.

CONCLUSIONS

The cases in this perinatal series of rhombencephalosynapsis showed a very poor prognosis. The presence of ventriculomegaly on prenatal ultrasound imaging should alert the physician to consider rhombencephalosynapsis in the differential diagnosis. MRI appears to be the imaging modality of choice in establishing the diagnosis.

Tubular aggregate myopathy associated with retinal degeneration

CASE REPORT

We report a case of congenital tubular aggregate myopathy associated with retinal degeneration.

COMMENTS

Bilateral, asymmetric retinal degeneration developed in a 37-year-old woman with a history of congenital tubular aggregate myopathy. The major pathological feature was the presence of tubular aggregates, believed to arise from the sarcoplasmic reticulum, which are present in skeletal muscles only. The abnormal functioning of the smooth muscles of the pupillary dilator, together with retinal degeneration in our patient, suggests that tubular aggregates may represent a more generalized disequilibrium of intracellular calcium homeostasis that may not be confined to skeletal muscles.

Loss of RB1 induces non-proliferative retinoma: increasing genomic instability correlates with progression to retinoblastoma

Retinoblastoma clinical observations revealed the role of tumor suppressor genes in human cancer, Knudson's 'two-hit' model of cancer induction. We now demonstrate that loss of both RB1 tumor suppressor gene alleles initiates quiescent RB1(-/-) retinomas with low level genomic instability and high expression of the senescence-associated proteins p16(INK4a) and p130. Although retinomas can remain unchanged throughout life, highly proliferative, clonal and aneuploid retinoblastomas commonly emerge, exhibiting altered gene copy number and expression of oncogenes (MYCN, E2F3, DEK, KIF14 and MDM4) and tumor suppressor genes (CDH11, p75(NTR)) and reduced expression of p16(INK4a) and p130. We suggest that RB1 inactivation in developing retina induces genomic instability, but senescence can block transformation at the stage of retinoma. However, stable retinoma is rarely clinically observed because progressive genomic instability commonly leads to highly proliferative retinoblastoma.

The Fetal Cerebellar Vermis

Fetal magnetic resonance provides a new tool in the imaging of the posterior fossa and is proving useful in cases that are difficult to assess sonographically by allowing further assessment of the fourth ventricle, cisterna magna, and vermian growth and development. We describe various criteria with which to evaluate vermian growth, including vermian biometry and the relationship between the superior and inferior lobes. We demonstrate 2 markers of normal vermian development: the primary fissure and fastigial point. We illustrate the tegmento-vermian angle, "closure" of the fourth ventricle, and communication of the fourth ventricle with the basal cisterns during development and in several disorders. We correlate those features with the expected embryological course of development and illustrate identification of these features and associated abnormalities of the posterior fossa, brain stem, and central nervous system in mid-trimester scans of fetuses with abnormal development. Correlation with contemporaneous ultrasound examinations is demonstrated.

West Nile virus-induced neuroinflammation: glial infection and capsid protein-mediated neurovirulence

West Nile virus (WNV) infection causes neurological disease at all levels of the neural axis, accompanied by neuroinflammation and neuronal loss, although the underlying mechanisms remain uncertain. Given the substantial activation of neuroinflammatory pathways observed in WNV infection, we hypothesized that WNV-mediated neuroinflammation and cell death occurred through WNV infection of both glia and neurons, which was driven in part by WNV capsid protein expression. Analysis of autopsied neural tissues from humans with WNV encephalomyelitis (WNVE) revealed WNV infection of both neurons and glia. Upregulation of proinflammatory genes, CXCL10, interleukin-1beta, and indolamine-2',3'-deoxygenase with concurrent suppression of the protective astrocyte-specific endoplasmic reticulum stress sensor gene, OASIS (for old astrocyte specifically induced substance), was evident in WNVE patients compared to non-WNVE controls. These findings were supported by increased ex vivo expression of these proinflammatory genes in glia infected by WNV-NY99. WNV infection caused endoplasmic reticulum stress gene induction and apoptosis in neurons but did not affect glial viability. WNV-infected astrocytic cells secreted cytotoxic factors, which caused neuronal apoptosis. The expression of the WNV-NY99 capsid protein in neurons and glia by a Sindbis virus-derived vector (SINrep5-WNVc) caused neuronal death and the release of neurotoxic factors by infected astrocytes, coupled with proinflammatory gene induction and suppression of OASIS. Striatal implantation of SINrep5-WNV(C) induced neuroinflammation in rats, together with the induction of CXCL10 and diminished OASIS expression, compared to controls. Moreover, magnetic resonance neuroimaging showed edema and tissue injury in the vicinity of the SINrep5-WNVc implantation site compared to controls, which was complemented by neurobehavioral abnormalities in the SINrep5-WNVc-implanted animals. These studies underscore the important interactions between the WNV capsid protein and neuroinflammation in the pathogenesis of WNV-induced neurological disorders.

Upregulation of Hypoxia-Inducible Factor (HIF)-1α and HIF-2α in Leptomeningeal Vascular Malformations of Sturge-Weber Syndrome

Cutaneous and leptomeningeal vascular malformations are hallmarks of the Sturge-Weber Syndrome (SWS), resulting in chronic ischemic tissue damage. The mechanisms underlying the pathobiology of these progressive lesions are unknown. Aberrant expression of angiogenic factors has been implicated in the genesis and maintenance of vascular malformations. To assess the role of angiogenesis in SWS vascular lesions we determined the expression of key angiogenic factors by immunohistochemistry and in situ hybridization in 8 SWS patients (age: 8 months to 18 years). We observed increased expression of vascular endothelial growth factor (VEGF), its cognate receptors VEGFR-1, VEGFR-2, and neuropilin (NP)-1 as well as Tie2 in leptomeningeal SWS blood vessels. Intriguingly, these factors are known to be transcriptionally induced by hypoxia-inducible factor (HIF). The HIF system has emerged as the key regulatory system of responses to hypoxia. Immunohistochemical analysis demonstrated markedly elevated nuclear HIF-1alpha and HIF-2alpha protein levels in SWS vessels. Concomitantly, SWS vessels revealed signs of enhanced endothelial cell (EC) turnover as evidenced by increased EC proliferation and apoptosis. Thus, in terms of angiogenesis, vascular malformations in SWS are not static lesions but constitute dynamic structures. Our observation of a dysregulated HIF-alpha expression in SWS vessels are in agreement with recent findings that EC-specific HIF activation provides a setting which supports and sustains angiogenesis and could be of potential use for developing therapeutic strategies to treat these currently incurable lesions.

Prenatal detection of microtia by MRI in a fetus with trisomy 22

Trisomy 22 is a rare chromosomal abnormality infrequently detected prenatally. External ear abnormalities, in particular microtia, are often associated with trisomy 22, but prenatal detection of microtia has not been reported in association with trisomy 22. We report a fetus with trisomy 22, with fetal MRI findings of microtia, craniofacial dysmorphism, and polygyria. Fetal MRI is a useful tool for auricular assessment and might have utility in the prenatal detection of chromosomal abnormalities, especially among fetuses with structural anomalies.

Massive Congenital Orbital Teratoma

Orbital teratomas are rare embryonic tumors composed of a wide diversity of tissues derived from the three germinal layers. The presenting features include, a healthy newborn with extreme unilateral proptosis; marked stretching of the eyelids over a tense, fluctuating mass, with elongation of the palpebral fissure; enlargement of the bony orbit (two to three times normal size) with subsequent nasal and malar deformities; and transillumination of all or part of the orbital mass. Commonly the eye is normally developed but often vision is not preserved either due to exposure or secondary optic atrophy. The objective in the management of orbital teratoma is to save the eye to encourage orbitofacial development, maintain cosmesis and retain some vision. We report a case of massive congenital orbital teratoma successfully removed by an eyelid-sparing exenteration technique.

Cavernous sinus thrombosis presenting with diplopia in an allogeneic bone marrow transplant recipient

Although neurological complications are common in patients undergoing allogeneic bone marrow transplant (alloBMT), cavernous sinus thrombosis (CST) has rarely been described. An allograft recipient is described who presented with diplopia and developed CST in the early post-transplant period likely caused by a filamentous fungus. Clinical course and serial radiological studies of this patient are described and correlated with autopsy findings.

Neurological manifestations of West Nile virus infection

BACKGROUND

Over the past four years, West Nile virus (WNV) has become a significant health issue in North America. In 2002, WNV infection made its first appearance in the human population in Canada.

METHODS

Patients who presented to the University Health Network and Mount Sinai Hospital in Toronto with neurological disease attributed to WNV infection were identified and followed by the neurology service. Clinical features and results of laboratory, electrodiagnostic, radiological and pathological studies are presented.

RESULTS

In August and September 2002, 26 patients were admitted with WNV infection; 14 presented with neurological illness. Encephalitis was the most common presentation (11 patients). Eleven patients developed neuromuscular disease; two at presentation and nine after encephalitis. While the majority had a motor process that localized to the anterior horn cell and/or motor neuron, two patients had evidence of a demyelinating neuropathy and one a sensorimotor axonal neuropathy. Less common manifestations included rhombencephalitis, ataxia, myelopathy and parkinsonism. Death occurred in four patients; two > 75 years of age, and two who were immunocompromised.

CONCLUSIONS

The most common neurological manifestation of WNV infection was encephalitis with subsequent neuromuscular involvement. The diversity of clinical and pathological findings, however, suggests widespread involvement of the central and peripheral nervous system. A poorer prognosis for neurological recovery and overall survival was seen in older and immunocompromised patients.

The effects of toluene on the central nervous system

In recent decades the organic solvent toluene (methylbenzene) has emerged as one of the best-studied neurotoxins. Long-term and intense exposure to toluene vapors in humans who abuse spray paint and related substances has led to the recognition that toluene has a severe impact on central nervous system myelin. Chronic toluene abuse produces a devastating neurological disorder, of which dementia is the most disabling component. The clinical syndrome, toluene leukoencephalopathy, can be detected by a combination of characteristic symptoms and signs, detailed neurobehavioral evaluation, and brain magnetic resonance imaging. In this paper, we consider the impact of toluene abuse on our society, describe the specific neurobehavioral deficits in toluene leukoencephalopathy, review the spectrum of neuroimaging findings in patients with this disorder, summarize the teratogenic effects of toluene in both humans and animal models, and offer possible explanations for the range of neuropathological damage seen in brains of individuals who chronically abuse toluene.

Determining the position and size of the subthalamic nucleus based on magnetic resonance imaging results in patients with advanced Parkinson disease

Object. The subthalamic nucleus (STN) is a target in surgery for Parkinson disease, but its location according to brain atlases compared with its position on an individual patient's magnetic resonance (MR) images is incompletely understood. In this study both the size and location of the STN based on MR images were compared with those on the Talairach and Tournoux, and Schaltenbrand and Wahren atlases.

Methods. The position of the STN relative to the midcommissural point was evaluated on 18 T2-weighted MR images (2-mm slices). Of 35 evaluable STNs, the most anterior, posterior, medial, and lateral borders were determined from axial images, dorsal and ventral borders from coronal images. These methods were validated using histological measurements in one case in which a postmortem examination was performed.

The mean length of the anterior commissure—posterior commissure was 25.8 mm. Subthalamic nucleus borders derived from MR imaging were highly variable: anterior, 4.1 to −3.7 mm relative to the midcommissural point; posterior, 4.2 to 10 mm behind the midcommissural point; medial, 7.9 to 12.1 mm from the midline; lateral, 12.3 to 15.4 mm from the midline; dorsal, 0.2 to 4.2 mm below the intercommissural plane; and ventral, 5.7 to 9.9 mm below the intercommissural plane.

The position of the anterior border on MR images was more posterior, and the medial border more lateral, than its position in the brain atlases. The STN was smaller on MR images compared with its size in atlases in the anteroposterior (mean 5.9 mm), mediolateral (3.7 mm), and dorsoventral (5 mm) dimensions.

Conclusions. The size and position of the STN are highly variable, appearing to be smaller and situated more posterior and lateral on MR images than in atlases. Care must be taken in relying on coordinates relative to the commissures for targeting of the STN.

Benign hereditary chorea: clinical, genetic, and pathological findings

Benign hereditary chorea is an autosomal dominant disorder presenting with childhood-onset chorea, no dementia, and little or no progression. We present a family with typical clinical features of benign hereditary chorea. Pathological investigation of the brain of an affected family member who died of an unrelated condition showed no significant gross or histological abnormalities. Genetic evaluation showed a novel single nucleotide substitution of intron 2 of the TITF-1 gene (also referred to as TTF, NKX2.1, and T/ebp) on chromosome 14 which is predicted to have drastic consequences on the maturation processes of TITF-1.

West Nile virus infection in 2002: morbidity and mortality among patients admitted to hospital in southcentral Ontario

BACKGROUND

In August and September 2002 an outbreak of West Nile virus (WNV) infection occurred in southern Ontario. We encountered a number of seriously ill patients at our hospitals. In this article we document the clinical characteristics of these cases.

METHODS

We conducted a retrospective chart review of patients who came to the attention of infectious disease or neurology consultants or the microbiology laboratories at 7 hospitals in the municipalities of Toronto, Peel and Halton, Ont. Patients were included if they had been admitted to hospital or stayed overnight in the emergency department, had serological evidence of WNV infection and had clinical evidence of WNV fever, aseptic meningitis, encephalomyelitis or motor neuronopathy.

RESULTS

In all, 64 patients met the inclusion criteria; 57 had encephalitis or neuromuscular weakness or both, 5 had aseptic meningitis, and 2 had WNV fever. The mean age was 61 years (range 26-87). The patients were predominantly active, middle-aged or elderly people living independently in the community. Seven patients were immunocompromised A febrile prodromal illness preceded the neurological symptoms in almost all cases. The most common neurological abnormality was decreased level of consciousness; this frequently evolved to severe lower motor neuron neuromuscular weakness. Ataxia and swallowing disorders were frequent and important problems. Sixteen patients (25%) required intubation and mechanical ventilation because of a decreased level of consciousness, inability to clear secretions or respiratory muscle weakness; 9 others had disabling muscle weakness of one or more limbs. Ten patients died. The study patients were in hospital a total of 1856 patient-days, including 532 patient-days in an intensive care unit. Only 28% (13/47) of the patients who survived encephalitis or neuromuscular weakness, or both, were discharged home without additional support. Slow turnaround time for serological test results resulted in delayed diagnosis.

INTERPRETATION

The 2002 WNV infection outbreak in Ontario caused serious morbidity and mortality in the subset of patients who had encephalitis or neuromuscular weakness severe enough to require hospital admission.