Antonella Cacchione

Wernicke Encephalopathy in Pediatric Neuro-oncology: Presentation of 2 Cases and Review of Literature

Wernicke encephalopathy represents a well-known entity characterized by a set of cognitive and neurologic alterations. Wernicke encephalopathy is rare and under-recognized in childhood and may be fatal. Few cases have been documented in pediatric oncology. We report on 2 Wernicke encephalopathy cases that occurred in children having a brain tumor. The diagnosis of Wernicke encephalopathy was suggested by clinical manifestations associated with the typical radiologic findings and a laboratory evidence of thiamine deficiency. No large series have been published to support the evidence that pediatric malignancies represent a demonstrated factor of increased risk to develop a Wernicke encephalopathy. Moreover, the diagnosis may be even more difficult in brain tumors, considering the overlapping symptoms and the risk of encephalopathy related to both the disease and the treatment. Wernicke encephalopathy should be considered in all children with cancer presenting a neurologic deterioration, mainly in brain tumors. An early diagnosis is imperative for a prompt therapy that might prevent or minimize the irreversible brain damage related to this condition.

Hyper-activation of Notch3 amplifies the proliferative potential of rhabdomyosarcoma cells.

Rhabdomyosarcoma (RMS) is a pediatric myogenic-derived soft tissue sarcoma that includes two major histopathological subtypes: embryonal and alveolar. The majority of alveolar RMS expresses PAX3-FOXO1 fusion oncoprotein, associated with the worst prognosis. RMS cells show myogenic markers expression but are unable to terminally differentiate. The Notch signaling pathway is a master player during myogenesis, with Notch1 activation sustaining myoblast expansion and Notch3 activation inhibiting myoblast fusion and differentiation. Accordingly, Notch1 signaling is up-regulated and activated in embryonal RMS samples and supports the proliferation of tumor cells. However, it is unable to control their differentiation properties. We previously reported that Notch3 is activated in RMS cell lines, of both alveolar and embryonal subtype, and acts by inhibiting differentiation. Moreover, Notch3 depletion reduces PAX3-FOXO1 alveolar RMS tumor growth in vivo. However, whether Notch3 activation also sustains the proliferation of RMS cells remained unclear. To address this question, we forced the expression of the activated form of Notch3, Notch3IC, in the RH30 and RH41 PAX3-FOXO1-positive alveolar and in the RD embryonal RMS cell lines and studied the proliferation of these cells. We show that, in all three cell lines tested, Notch3IC over-expression stimulates in vitro cell proliferation and prevents the effects of pharmacological Notch inhibition. Furthermore, Notch3IC further increases RH30 cell growth in vivo. Interestingly, knockdown of Notch canonical ligands JAG1 or DLL1 in RMS cell lines decreases Notch3 activity and reduces cell proliferation. Finally, the expression of Notch3IC and its target gene HES1 correlates with that of the proliferative marker Ki67 in a small cohort of primary PAX-FOXO1 alveolar RMS samples. These results strongly suggest that high levels of Notch3 activation increase the proliferative potential of RMS cells.

IDO1 involvement in mTOR pathway: a molecular mechanism of resistance to mTOR targeting in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children. Despite therapeutic advancements, high-risk groups still present significant mortality. A deeper knowledge of the signaling pathways contributing to MB formation and aggressiveness would help develop new successful therapies. The target of rapamycin, mTOR signaling, is known to be involved in MB and is already targetable in the clinical setting. Furthermore, mTOR is a master metabolic regulator able to control cell growth versus autophagy decisions in conditions of amino-acid deprivation that can be due to IDO1 enzymatic activity. IDO1 has been also implicated in the regulation of inflammation, as well as of T cell-mediated immune responses, in a variety of pathological conditions, including brain tumors. In particular, IDO1 induces expansion of regulatory T-cells (Treg), preventing immune response against tumor cells. Analysis of 27 MB tissue specimens for the expression of both mTOR and IDO1 showed their widespread expression in all samples. Testing their cooperation in vitro, a significant involvement of IDO1 in mTOR immunogenic pathway was found, able to counteract the aim of rapamycin treatment. In MB cell lines, inhibition of mTOR strongly induced IDO1 expression and activity, corroborating its ability to recruit Treg cells in the tumor microenvironment. The mTOR/IDO1 cross talk was found to be strictly specific of MB cells. We demonstrated that mTOR pathway cross talks with IDO1 pathway to promote MB immune escape, possibly contributing to failure of mTOR- targeted therapy.

Behavioral disorders as unusual presentation of pediatric extraventricular neurocytoma: report on two cases and review of the literature

BackgroundExtraventricular neurocytomas (EVNs) are rare parenchymal brain tumors, distinct from central neurocytomas that are typically located within the supratentorial ventricular system. Seizures and headache represent the most common symptoms of extraventricular neurocytomas in the cerebral hemisphere both in adult and pediatric population.Case presentationWe describe two cases of pediatric EVN with clinical onset characterized by behavioral and attention deficit/ hyperactivity disorders. The association between behavioral/attention disorders in childhood and the presence of a frontal neurocytoma has never been described before. Furthermore, inappropriate levels of inattention, hyperactivity and impulsivity are common among the neurobehavioral and developmental disorders in childhood. We reviewed 43 pediatric cases of extraventricular neurocytoma included in the PubMed database and their clinical presentation, and we never found this unusual relationship.ConclusionIn childhood, the attention/hyperactivity disorders seem to be often over-diagnosed. When these deficits are more subtle and do not well-fit in a specific neurocognitive disorder, the clinicians should have a suspicion that they might mask the clinical features of a frontal lesion. This paper is focused on the clinical presentation of the extraventricular neurocytoma and the possible organic etiology of an attention and hyperactivity deficit.

Robot-Assisted Stereotactic Biopsy of Diffuse Intrinsic Pontine Glioma: A Single-Center Experience

BACKGROUND Diffuse intrinsic pontine glioma (DIPG) is a childhood tumor with a dismal prognosis. Emerging molecular signatures have paved the way for stereotactic biopsy in selected centers. We present our experience in DIPG stereotactic needle biopsy using the Robotic Stereotactic-Assisted system (ROSA) in a series of consecutive pediatric patients. METHODS All stereotactic biopsy procedures for DIPG performed during the last year at our institution were considered. All procedures were carried out using the ROSA surgical assistant through a precoronary approach. All children underwent a postoperative computed tomography scan to document possible surgical complications and confirm the site of biopsy. Postoperative clinical changes were recorded to test morbidity of the procedure. RESULTS In the last year, we performed 7 pontine needle biopsies. Specimens were diagnostic and useful for molecular analysis in all cases. No surgical complications were observed. One child showed a transient neurologic worsening related to the biopsy that resolved within 2 weeks. The combination of the precoronary approach and use of the stereotactic ROSA system allowed single-session surgeries in all cases. CONCLUSIONS Pontine biopsy for DIPG is a safe procedure in selected centers. The advantages of the single-session procedure we described might be of particular interest in the pediatric setting.

Magnetic resonance imaging patterns of treatment-related toxicity in the pediatric brain: an update and review of the literature

Treatment-related neurotoxicity is a potentially life-threatening clinical condition that can represent a diagnostic challenge. Differentiating diagnoses between therapy-associated brain injury and recurrent disease can be difficult, and the immediate recognition of neurotoxicity is crucial to providing correct therapeutic management, ensuring damage reversibility. For these purposes, the knowledge of clinical timing and specific treatment protocols is extremely important for interpreting MRI patterns. Neuroradiologic findings are heterogeneous and sometimes overlapping, representing the compounding effect of the different treatments. Moreover, MRI patterns can be acute, subacute or delayed and involve different brain regions, depending on (1) the mechanism of action of the specific medication and (2) which brain regions are selectively vulnerable to specific toxic effects. This review illustrates the most common radiologic appearance of radiotherapy, chemotherapy and medication-associated brain injury in children, with special focus on the application of advanced MRI techniques (diffusion, perfusion and proton spectroscopy) in the diagnosis of the underlying processes leading to brain toxicity.

Growth hormone excess in children with neurofibromatosis type-1 and optic glioma

In children with neurofibromatosis type 1 (NF1) and optic pathways glioma (OPG), growth hormone (GH) excess has been rarely reported and mainly associated to central precocious puberty. The aim of our study is to evaluate the prevalence of GH excess, the association with central precocious puberty, the relation with tumor site and the evolution over time in a large cohort of children with NF1 and OPG. Sixty‐four NF1 children with OPG were evaluated. Patients with stature and/or height velocity >2 SD for age were studied for GH secretion. Seven out of 64 children (10.9%) with NF1 and optic pathways glioma showed GH excess, isolated in 5 cases and associated to central precocious puberty in 2. All the children with GH excess had a tumor involving the chiasma. Children with GH excess underwent medical treatment with lanreotide and a minimum clinical/biochemical follow up of 2 years is reported. The present study demonstrates that GH excess should be considered as a relative frequent endocrine manifestation in NF1 patients, similarly to central precocious puberty. Therefore, these patients should undergo frequent accurate auxologic evaluations. On the other hand, an increase in height velocity in children with NF1, even despite normal ophthalmological exams, can suggest the presence of OPG and therefore represents an indication to perform brain MRI.

A dedicated protocol and environment for central venous catheter removal in pediatric patients affected by onco-hematological diseases

Purpose The removal of long-term central venous catheters (CVCs) is not performed according to evidence-based guidelines, thus conveying the message that it is a procedure of secondary importance. Our study aims at comparing the experience at Bambino Gesù Pediatric Hospital before and after the implementation of a dedicated protocol and the identification of a specific area to perform such a procedure under the so-called nonoperating room anesthesia (NORA). Methods Starting on January 1, 2010, an appropriate protocol regarding long-term CVC removal was applied. Then, data from all patients who underwent CVC removal under NORA regimen were compared with patients who have undergone the same procedure before the beginning of such protocol in terms of complication rate, duration of procedure, and costs. Results Between January 2010 and December 2012, 266 patients were evaluated for long-term CVC removal under a NORA regimen. Of these, 194 underwent the procedure. In the period from January 2007 to December 2009, 60 out of 82 patients scheduled for elective removal of long-term CVC in the operating theatre were eligible for this study. Median procedure time was 7 min for removal in NORA and 10 min for the operating theatre (p=0.016); no complications occurred. Conclusion Long-term CVC removal is an often-neglected procedure, carrying a small, but definite rate of complications. Our study shows that CVC removal performed in NORA regimen is safe and feasible, also allowing multiple procedures in the same session with prompt management of possible complications and reduction of the anxiety and pain associated with the procedure.

Anomalous vascularization in a Wnt medulloblastoma: a case report.

BackgroundMedulloblastoma is the most common malignant brain tumor in children. To date only few cases of medulloblastoma with hemorrhages have been reported in the literature. Although some studies speculate on the pathogenesis of this anomalous increased vascularization in medulloblastoma, the specific mechanism is still far from clearly understood. A correlation between molecular medulloblastoma subgroups and hemorrhagic features has not been reported, although recent preliminary studies described that WNT-subtype tumors display increased vascularization and hemorrhaging.Case presentationHerein, we describe a child with a Wnt-medulloblastoma presenting as cerebellar-vermian hemorrhagic lesion. Brain magnetic resonance imaging (MRI) showed the presence of a midline posterior fossa mass with a cystic hemorrhagic component. The differential diagnosis based on imaging included cavernous hemangioma, arteriovenous malformation and traumatic lesion. At surgery, the tumor appeared richly vascularized as documented by the preoperative angiography.ConclusionsThe case we present showed that Wnt medulloblastoma may be associated with anomalous vascularization. Further studies are needed to elucidate if there is a link between the hypervascularization and the Wnt/β-catenin signaling activation and if this abnormal vasculature might influence drug penetration contributing to good prognosis of this medulloblastoma subgroup.

MRI features as a helpful tool to predict the molecular subgroups of medulloblastoma: state of the art

Medulloblastoma is the most common malignant pediatric brain tumor. Medulloblastoma should not be viewed as a single disease, but as a heterogeneous mixture of various subgroups with distinct characteristics. Based on genomic profiles, four distinct molecular subgroups are identified: Wingless (WNT), Sonic Hedgehog (SHH), Group 3 and Group 4. Each of these subgroups are associated with specific genetic aberrations, typical age of onset as well as survival prognosis. Magnetic resonance imaging (MRI) is performed for all patients with brain tumors, and has a key role in the diagnosis, surgical guidance and follow up of patients with medulloblastoma. Several studies indicate MRI as a promising tool for early detection of medulloblastoma subgroups. The early identification of the subgroup can influence the extent of surgical resection, radiotherapy and chemotherapy targeted treatments. In this article, we review the state of the art in MRI-facilitated medulloblastoma subgrouping, with a summary of the main MRI features in medulloblastoma and a brief discussion on molecular characterization of medulloblastoma subgroups. The main focus of the article is MRI features that correlate with medulloblastoma subtypes, as well as features suggestive of molecular subgroups. Finally, we briefly discuss the latest trends in MRI studies and latest developments in molecular characterization.