Cerebellar Pilocytic Astrocytoma Research Articles

QLTI-02. THE ROLE OF REOPERATION IN PAEDIATRIC PILOCYTIC ASTROCYTOMA

Abstract INTRO Cerebellar pilocytic astrocytomas (cPAs) in childhood have long been recognized to have a good prognosis after total resection, but the outcome after incomplete resective surgery remains largely unpredictable, with the incidence of radiological progressive disease ranging from 18-100%. It has been traditionally thought that gross-total resection was required for long-term survival, and small residuals were classically resected in a subsequent operation. OBJECTIVE To determine the role of reoperation in residual or recurrent cerebellar pilocytic astrocytoma. METHODS The authors analyzed their pediatric low-grade clioma (PLGG) database for cases treated between 1985-2020 and filtered for intracranial PAs, to determine what clinical or radiological factors precipitated revisional resective surgery in their single quaternary care center cohort. RESULTS Using the PLGG database, 283 patients <18 years of age were identified to have a histopathological diagnosis or intracranial PA between 1985-2020, of which, 200 were within the cerebellum (70.7%). The majority of patients with cPA were between 1 and 10 years of age (n=145, 72.5%) without gender preponderance (M/F=99:101) usually presenting with 1 lesion (n=197, 98.5%). Gross total resection was achieved in 74.5% (n=149) of initial surgeries for cPA. In patients with subtotal resection, the mean largest diameter of the postoperative residual tumor was 1.06cm (range 0-2.95cm). Seven patients with subtotal resection did not require a second resective intervention. In 31 patients the neuro-oncology multi-disciplinary team recommended a second resection at a mean time interval of 22.9 months (range 0.13-81.6 months) from the initial surgery. Proportionally, the children who underwent multiple resections were also more likely to receive adjuvant chemo/radiotherapy. Functionally, the children in the multiple operation cohort experienced more complications of therapy including ongoing endocrinopathy, treatment-associated hearing deficit, and neuro-cognitive deficits. CONCLUSION Residual disease in cPA should be maintained under clinico-radiological surveillance postoperatively with adoption of a more conservative approach when residual disease is not significantly changing over time.

LGG-28. THE ROLE OF REOPERATION IN PEDIATRIC CEREBELLAR PILOCYTIC ASTROCYTOMA

Abstract BACKGROUND Cerebellar pilocytic astrocytomas (cPAs) in childhood have long been recognized to have a good prognosis after total resection but the outcome after incomplete resective surgery remains largely unpredictable with the incidence of radiological progressive disease ranging from 18-100%. Traditionally thought that GTR was required for long-term survival, small residuals were classically resected in a subsequent operation. METHODS We analyzed our Pediatric Low-Grade Glioma (PLGG) database, between 1985 and 2020, and filtered for intracranial pilocytic astrocytomas to determine what clinical or radiological factors precipitated revisional resective surgery in our single quaternary center cohort. RESULTS Using our Pediatric Low-Grade Glioma (PLGG) database, 283 patients were identified to have a histopathological diagnosis of intracranial pilocytic astrocytoma between 1985-2020 of which 202 were within the cerebellum (68.2%). The majority of patients with cerebellar PA were between 1-10 years of age (n=147, 73.5%) without gender predominance (M:F=99:101), usually presenting with 1 lesion (n=197, 98.5%). Gross total resection (GTR) was achieved in 74.5% (n=149) of initial surgeries for cerebellar PA. In patients with NTR or STR, the mean largest diameter of the post-operative residual was 1.1cm (0.2-3.7cm). Seven patients with STR did not require a second resective intervention. In 31 patients the neuro-oncology multidisciplinary team (MDT) recommended a second surgical resection at a mean time interval of 22.9 months (0.13-81.6 months) from the initial surgery. Proportionally, the children who underwent multiple resections were also more likely to receive adjuvant chemo/radiotherapy. Functionally, the children in the multiple operation cohort experienced more complications of therapy including ongoing endocrinopathy, treatment-associated hearing deficit, and neurocognitive deficits. CONCLUSION Residual disease in cPA should be maintained under clinocoradiological surveillance post-operatively with adoption of a more conservative approach when residual disease is not significantly changing over time.

The role of reoperation in pediatric cerebellar pilocytic astrocytoma.

Cerebellar pilocytic astrocytomas (cPAs) in childhood have long been recognized to have a good prognosis after total resection, but the outcome after incomplete resective surgery remains largely unpredictable, with the incidence of radiological progressive disease ranging from 18% to 100%. It has been traditionally thought that gross-total resection was required for long-term survival, and small residuals were classically resected in a subsequent operation. The authors analyzed their pediatric low-grade glioma (PLGG) database for cases treated between 1985 and 2020 and filtered for intracranial PAs, to determine what clinical or radiological factors precipitated revisional resective surgery in their single quaternary care center cohort. Using the pediatric low-grade glioma database, 283 patients were identified to have a histopathological diagnosis of intracranial PA between 1985 and 2020, of which 200 lesions were within the cerebellum (70.7%). The majority of patients with cPA were between 1 and 10 years of age (n = 145, 72.5%) without gender predominance (M/F = 99:101), usually presenting with 1 lesion (n = 197, 98.5%). Gross-total resection was achieved in 74.5% (n = 149) of initial surgeries for cPA. In patients with subtotal resection, the mean largest diameter of the postoperative residual tumor was 1.06 cm (range 0-2.95 cm). Seven patients with subtotal resection did not require a second resective intervention. In 31 patients the neuro-oncology multidisciplinary team recommended a second resection at a mean time interval of 22.9 months (range 0.13-81.6 months) from the initial surgery. Proportionally, the children who underwent multiple resections were also more likely to receive adjuvant chemo/radiotherapy. Functionally, the children in the multiple operation cohort experienced more complications of therapy including ongoing endocrinopathy, treatment-associated hearing deficit, and neurocognitive deficits. Residual disease in cPA should be maintained under clinicocoradiological surveillance postoperatively with adoption of a more conservative approach when residual disease is not significantly changing over time.

Intra-axial Hepatic Cerebrospinal Fluid Pseudocyst: An Unusual Complication of Ventriculoperitoneal Shunt Placement

Intra-abdominal Cerebrospinal Fluid (CSF) pseudocysts are a well-known and potentially serious complication of Ventriculoperitoneal (VP) shunt placement. These cysts are often found within the peritoneal cavity or along the serosal surface of solid organs. Here, we present an unusual case of an intrahepatic CSF pseudocyst in a 14-year-old female patient with a VP shunt placed three years ago, following the excision of a cerebellar pilocytic astrocytoma. The child presented with complaints of right hypochondriac pain and tenderness for one month. On ultrasound of the abdomen, the right lobe of the liver showed a complex anechoic cystic collection with multiple thick internal septations. A Contrast-enhanced Computed Tomography (CECT) examination revealed a well-defined hypodense collection in segments IV and V of the liver with a VP shunt tube within. Based on clinical and imaging features, differentials of intra-axial intrahepatic CSF pseudocyst, complex hepatic cyst, peri-shunt hemorrhagic cyst, and biliary cystadenoma were considered. Aspiration of the cyst revealed clear, colourless, non purulent, non sanguineous fluid which tested positive for beta-2-transferrin, confirming the collection to be a CSF pseudocyst. An elective laparoscopic cyst excision with shunt revision was performed with no recurrence on follow-up. The present case highlights the uncommon occurrence of intrahepatic CSF pseudocysts post-VP shunt, necessitating meticulous diagnostic evaluation. Successful laparoscopic excision and shunt revision underscore the efficacy of tailored interventions. This contribution enhances the understanding of atypical complications in VP shunt recipients, guiding clinicians and radiologists in both diagnosis and management.

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The paper describes the case of a 3-year-old girl presenting with worsening and severe headache initially attributed to astigmatism that was finally diagnosed as cerebellar pilocytic astrocytoma.

Infiltration in Pilocytic Astrocytoma: A Diagnostic Pitfall.

Glioma can be classified according to its infiltrative capacity into circumscribed and "diffuse"/infiltrative glioma. Pilocytic astrocytoma is typically grouped under the circumscribed astrocytic glioma in the 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors. The distinction of pilocytic astrocytoma from diffuse glioma is fundamental as it could be the difference between CNS WHO grade 1 and grade 4 glioma. This study aims to determine the infiltrative nature of pilocytic astrocytoma in different brain locations. All cases diagnosed as "pilocytic astrocytoma" were retrieved from 2008 to 2021. The clinical information (age, sex, location of the tumor), pathological description, and performed immunostaining were obtained from the pathological reports. The available pathological slides were retrieved and examined for the following features: diagnosis, infiltrative vs. circumscribed tumor, and immunostaining characteristics. There were 20 males and 19 females aged 17 months to 31 years. The diagnosis of pilocytic astrocytoma was confirmed in 38/39 cases, and in one case, the diagnosis changed to a dysembryoplastic neuroepithelial tumor. Histological infiltration is defined as the presence of neoplastic cells among the nonneoplastic brain parenchyma. Twenty cases were well-circumscribed with no evidence of infiltration histologically, while 18/38 cases showed apparent infiltration into adjacent brain tissue. The infiltration was not restricted to cerebellar pilocytic astrocytoma (12/24, 50%) but was also present in 3/7 supratentorial, single brainstem, and single spinal cord cases. In conclusion, cases with typical morphological features of pilocytic astrocytoma could show areas of brain infiltration, which should not affect the certainty of the diagnosis.

Novel Use of the Aurora Surgiscope System for Minimally Invasive Resection of Intraparenchymal Lesions: A Case Series.

Minimally invasive surgery (MIS) for intracranial pathology minimizes surgical morbidity but can come at the cost of operator ergonomics and technical surgical success. Here, the authors present a case series to report the first use of a novel 15-mm tubular retraction system with integrated lighting and visualization capabilities for MIS access to intracranial lesions. To demonstrate feasibility and effectiveness of the 15-mm Aurora Surgiscope (Integra Lifesciences) for intracranial MIS approaches. The 15-mm Aurora Surgiscope facilitated MIS approach to gain access to intraparenchymal pathologies. The device consists of a tubular access system with integrated light source and a reusable control unit that modifies video parameters. The port was inserted along a preplanned trajectory through a mini-craniotomy. Bimanual access allowed the surgeon to comfortably dissect/resect lesional tissue using high-quality video. Four patients are presented. In cases 1 and 2, the authors evacuated acute intracerebral hemorrhages. Both had <15 cc hemorrhage with improved or stable neurological examination. In case 3, the authors performed gross total resection of a cerebellar pilocytic astrocytoma. In case 4, the authors resected a mesial posterior temporal cavernoma. No perioperative/technical complications were noted. The Aurora Surgiscope system is a novel integrated tubular retraction, lighting, and visualization system that allows access to a wide variety of pathologies using a MIS approach. The Surgiscope allows the surgeon to use bimanual dexterity through a small access port while limiting the need for additional equipment such as microscope, exoscope, or endoscope.

IMG-03. Impact of childhood cerebellar tumor surgery on cognition: Can fMRI serve as a surrogate marker?

BACKGROUND: Childhood cerebellar pilocytic astrocytomas harbour excellent overall survival rates after surgical resection, but the patients may exhibit specific cognitive and behavioural problems emphasising our current understanding of the cerebellar role in cognition. Functional MRI has catalysed the mechanistic insights into brain functional systems and has already been linked with the neuropsychological performance. We aimed to exploit the question whether functional MRI can be used as a surrogate measure for the cognitive outcome assessment of these patients. METHODS: We investigated 13 patients (median age 22.0 years, range 15.2 – 31.7) after a median interval between surgery and examination of 15.0 years (range 4.2 – 20.8) and 16 matched controls. All subjects underwent a functional 3T MRI scans in a resting state condition and a battery neuropsychological tests. RESULTS: Patients showed a significantly increased functional connectivity in the precuneus compared to controls (p<0.05) and at the same time impairments in various domains of neuropsychological functioning such as a lower mean WIE IQ percentile (M = 48.62, SD = 29.14), lower scores in the TMT letter sequencing (M = 49.54, SD = 30.66), worse performance on the WIE subtest Digit Symbol Coding (M = 38.92, SD = 35.29), subtest Symbol Search (M = 40.75, SD = 35,28), and TAP divided attention task (M = 783.92, SD = 73.20). CONCLUSION: Functional MRI has the potential to serve as a surrogate measure for the cognitive outcome assessment. The precuneus brain region is heavily involved in the cerebral associative oversight of cerebellar cognitive function.

Outcome of Childhood Cerebellar Pilocytic Astrocytoma: A Series With 20 Years of Follow Up.

Background: Cerebellar pilocytic astrocytoma (PCA) is one of the few CNS tumors that can be cured with gross-total removal (GTR). In this series, we had 39 patients diagnosed with cerebellar PCA, 27 patients (70%) had GTR, and mean follow-up period was 62 months with no tumor recurrence.Objective: To assess the long-term outcome of childhood cerebellar PCA treated at our institute during the period 2000-2020 and to highlight our surgical protocol.Methodology: Retrospective review of all patients under 18 years of age who were diagnosed with cerebellar PCA and had surgical excision between 2000 and 2020 at the Medical City of King Saud University.Results: The study included 39 patients: 17 males and 22 females, the mean age was 8.4 years. Radiologically, the tumor was solid in eight patients, cystic in 15 patients, and mixed components were found in 16 patients. The lesion was located in the right cerebellar hemisphere in 12 patients, left cerebellar hemisphere in five patients, and midline 22 patients. The tumor size ranged from 2 to 7 cm in its greatest diameter, it was <5 cm in 13 patients and >5 cm in 26 patients. Thirty-one patients had preoperative hydrocephalus. GTR of the tumor was achieved in 27 patients and subtotal resection (STR) was done in 12 patients, 18 patients required permanent ventriculoperitoneal (V-P) shunt, and five patients had postoperative radiotherapy. Postoperative complications included infection in two patients, cerebellar mutism in two patients, and significant neurologic disability in four patients. The duration of follow-up ranged from 0 to 240 months (mean follow-up period: 62.0 months). The outcome at 10 years was good in 30 patients, fair in four patients, poor in four patients, and one patient died. Recurrence was documented in nine patients, seven of them had GTR and two had STR.Conclusion: GTR, if achievable, is curative for childhood cerebellar PCA. Many posterior fossa surgical complications could be avoided with watertight dural closure. Although new dural substitutes are available we prefer using autologous grafts (pericranium). It is easy to harvest pericranial graft from the external ventricular drain (EVD) site. The insertion of EVD synchronously with GTR of the tumor and gradual weaning of EVD could avoid the insertion of V-P shunt.

The Utility of Intraoperative Magnetic Resonance Imaging in the Resection of Cerebellar Hemispheric Pilocytic Astrocytomas: A Cohort Study.

The mainstay of treatment for cerebellar pilocytic astrocytomas in the pediatric population is surgery. The use of intraoperative magnetic resonance imaging (iMRI) as a surgical adjunct may lower the likelihood of reoperation. Studies have examined iMRI in heterogenous tumor populations, but few have looked at single pathologies. To compare iMRI vs non-iMRI for hemispheric cerebellar pilocystic astrocytomas, specifically looking at revision surgeries and residual disease in follow-up. Retrospective review of medical records for 60 sequential patients with cerebellar hemispheric pilocytic astrocytoma at a single institution was conducted. Thirty-two patients with cerebellar pilocytic astrocytoma underwent surgery without iMRI, whereas 28 patients underwent surgical resection with iMRI. All patients had at least 3-year follow-up. There were no significant differences between the patient populations in age, tumor size, or need for cerebrospinal fluid diversion between groups. Operative time was shorter without iMRI (without iMRI 4.4 ± 1.3 hours, iMRI 6.1 ± 1.5, P = .0001). There was no significant difference in the patients who had repeat surgery within 30 days (9% without iMRI, 0% iMRI, P = .25), residual disease at 3 months (19% without iMRI, 14% iMRI, P = .78), or underwent a second resection beyond 30 days (9% without iMRI, 4% iMRI, P = .61). There were more total reoperations in the group without iMRI, although this did not reach significance (19% vs 4%, P = .11). For hemispheric cerebellar pilocytic astrocytomas, iMRI tended to leave less residual and fewer reoperations; however, neither of these outcomes achieved statistical significance leaving utilization to be determined by the surgeon.

Diagnostic assertiveness of cerebellar pilocytic astrocytoma in the pediatric age

Pilocytic astrocytoma of the cerebellum in the pediatric age is the most frequent benign tumor lesion of the nervous system in children according to the WHO. International literature mentions that being low-grade tumors they have a high curative capacity. If the entire tumor is resected, when it is completely removed, survival increases with a high quality of life for children who presented this pathology and was treated on time. However, the delay in diagnosis and therefore in its treatment could generate the possibility of tumor transformation, the malignant nature of the transformed injuries has a very high morbidity and mortality, without mentioning that the degree of cognitive sequelae greatly affects the quality of life of the survivors. That is why the training of pediatric and non-pediatric first contact doctors imply a great responsibility since it gives the population and patients suffering from this nosology the possibility to improve their future life, as well as reduce the cost of the impact caused by the injuries they suffer. On the other hand, these tumors can transform generating devastating prognoses, without taking into account the economic and social repercussions of patients suffering from a low-grade tumor. When it is detected and treated assertively in a timely manner, it offers them greater opportunities than those who did not have such a timely diagnosis.

Cerebellar pilocytic astrocytoma

Pilocytic astrocytomas (PAs) are the most common pediatric primary brain tumor. They are World Health Organization Grade 1 tumors with an excellent prognosis. In children, the cerebellum, optic nerve chiasm, and hypothalamic region are the most common locations in that order. Clinically, cranial nerve palsies, symptoms of raised intracranial pressure, and ataxia are commonly seen. We present an unusual case of PA in a 3-year-old toddler with inability to walk. High index of suspicion is required for the diagnosis of posterior fossa tumors in this age group as they can deteriorate rapidly.

ADULT CEREBELLAR PILOCYTIC ASTROCYTOMA PRESENTING AS HEMORRHAGE - A CONFOUNDING ENTITY

ABSTRACT : Pilocytic astrocytomas are histologically benign low-grade astrocytic tumors seen predominantly during the first two decades of life. Pilocytic astrocytomas in the adult population as well as the hemorrhagic manifestation of pilocytic astrocytomas are quite uncommon. Here we present a case of the hemorrhagic manifestation of cerebellar pilocytic astrocytoma in a 48yr old male who presented with a history of vertigo and headache for a week

Impact of childhood cerebellar tumor surgery on cognition revealed by precuneus hyperconnectivity.

BackgroundChildhood cerebellar pilocytic astrocytomas harbor excellent overall survival rates after surgical resection, but the patients may exhibit specific cognitive and behavioral problems. Functional MRI has catalyzed insights into brain functional systems and has already been linked with the neuropsychological performance. We aimed to exploit the question of whether resting-state functional MRI can be used as a biomarker for the cognitive outcome assessment of these patients.MethodsWe investigated 13 patients (median age 22.0 years; range 14.9-31.3) after a median interval between surgery and examination of 15.0 years (range 4.2-20.5) and 16 matched controls. All subjects underwent functional 3-Tesla MRI scans in a resting-state condition and battery neuropsychological tests.ResultsPatients showed a significantly increased functional connectivity in the precuneus compared with controls (P < .05) and at the same time impairments in various domains of neuropsychological functioning such as a lower mean Wechsler Intelligenztest für Erwachsene (WIE) IQ percentile (mean [M] = 48.62, SD = 29.14), lower scores in the Trail Making Test (TMT) letter sequencing (M = 49.54, SD = 30.66), worse performance on the WIE subtest Digit Symbol Coding (M = 38.92, SD = 35.29), subtest Symbol Search (M = 40.75, SD = 35.28), and test battery for attentional performance (TAP) divided attention task (M = 783.92, SD = 73.20).ConclusionChildhood cerebellar tumor treated by resection only strongly impacts the development of precuneus/posterior cingulate cortex functional connectivity. Functional MRI has the potential to help deciphering the pathophysiology of cerebellar-related cognitive impairments in these patients and could be an additional tool in their individual assessment and follow-up.

Large Residual Pilocytic Astrocytoma After Failed Ultrasound-Guided Resection: Intraoperative Ultrasound Limitations Require Special Attention

While benefits of neurosurgical intraoperative ultrasound (IOUS) are reported frequently, this method still has some significant pitfalls, which are described less often. However, sufficient knowledge on dealing with IOUS drawbacks, particularly various image artifacts, is important for successful surgery. We report a case of failed IOUS-guided pediatric cerebellar pilocytic astrocytoma resection, incorrectly evaluated as gross total resection according to IOUS. A large tumor residuum was left in place. Successful IOUS-guided reoperation using new IOUS technology and appropriate ultrasound imaging technique are described. The most probable reasons for initial resection failure and crucial points of reoperation, predominantly dealing with IOUS artifacts, are discussed. Neurosurgeons should be aware of IOUS limitations and have sufficient knowledge about how to overcome them before adopting routine use of this intraoperative imaging modality.

TBIO-09. IN SILICO ANALYSIS IDENTIFIES A PUTATIVE CELL-OF-ORIGIN FOR BRAF FUSION-POSITIVE CEREBELLAR PILOCYTIC ASTROCYTOMA

Childhood cancers are increasingly recognized as disorders of cellular development. This study sought to identify the cellular and developmental origins of cerebellar pilocytic astrocytoma, the most common brain tumor of childhood. By leveraging publicly available gene expression data from such tumors and controlling for driver mutations, a set of eight known neuro-developmental genes were identified as being upregulated in cerebellar pilocytic astrocytoma. Mapping those genes onto mouse neuro-developmental atlases identified significant overlap in their expression within the ventricular zone of the cerebellar anlage. Further analysis with a single cell RNA-sequencing atlas of the developing mouse cerebellum defined this overlap as occurring in ventricular zone progenitor cells at the division point between GABA-ergic neuronal and glial lineages, a developmental trajectory which closely mirrors that previously described to occur within pilocytic astrocytoma cells. Furthermore, ventricular zone progenitor cells and their progeny exhibited evidence of MAPK pathway activation, the paradigmatic oncogenic cascade known to be active in cerebellar pilocytic astrocytoma. Gene expression from developing human brain atlases recapitulated the same anatomic localizations and developmental trajectories as those found in mice. Taken together, these data suggest this population of ventricular zone progenitor cells as the cell-of-origin for BRAF fusion-positive cerebellar pilocytic astrocytoma.

IMG-22. A DEEP LEARNING MODEL FOR AUTOMATIC POSTERIOR FOSSA PEDIATRIC BRAIN TUMOR SEGMENTATION: A MULTI-INSTITUTIONAL STUDY

BACKGROUNDBrain tumors are the most common solid malignancies in childhood, many of which develop in the posterior fossa (PF). Manual tumor measurements are frequently required to optimize registration into surgical navigation systems or for surveillance of nonresectable tumors after therapy. With recent advances in artificial intelligence (AI), automated MRI-based tumor segmentation is now feasible without requiring manual measurements. Our goal was to create a deep learning model for automated PF tumor segmentation that can register into navigation systems and provide volume output.METHODS720 pre-surgical MRI scans from five pediatric centers were divided into training, validation, and testing datasets. The study cohort comprised of four PF tumor types: medulloblastoma, diffuse midline glioma, ependymoma, and brainstem or cerebellar pilocytic astrocytoma. Manual segmentation of the tumors by an attending neuroradiologist served as “ground truth” labels for model training and evaluation. We used 2D Unet, an encoder-decoder convolutional neural network architecture, with a pre-trained ResNet50 encoder. We assessed ventricle segmentation accuracy on a held-out test set using Dice similarity coefficient (0–1) and compared ventricular volume calculation between manual and model-derived segmentations using linear regression.RESULTSCompared to the ground truth expert human segmentation, overall Dice score for model performance accuracy was 0.83 for automatic delineation of the 4 tumor types.CONCLUSIONSIn this multi-institutional study, we present a deep learning algorithm that automatically delineates PF tumors and outputs volumetric information. Our results demonstrate applied AI that is clinically applicable, potentially augmenting radiologists, neuro-oncologists, and neurosurgeons for tumor evaluation, surveillance, and surgical planning.

CS-01 Rapid Recurrence and Anaplastic Transformation of a Pilocytic Astrocytoma in an Elderly Patient

BACKGROUND: Rapid recurrence of a pilocytic astrocytoma with anaplastic transformation is extremely rare. The case of an elderly patient with a cerebellar pilocytic astrocytoma with anaplastic transformation during short-term follow-up is reported. CASE DESCRIPTION: An 83-year-old woman presented initially with dizziness and a gait deviation to the right. Magnetic resonance imaging (MRI) demonstrated a homogeneously enhanced mass in the right cerebellar hemisphere, and the tumor was subtotally removed by right suboccipital craniotomy. Histological examination showed that the tumor cells contained eosinophilic cytoplasm and spindle-shaped processes with Rosenthal fibers and eosinophilic granular bodies, diagnosed as a typical pilocytic astrocytoma (PA). The MIB-1 index was less than 1%. The patient did not receive postoperative adjuvant radiation and chemotherapy. Two months after surgery, MRI showed growth of the residual tumor adjacent to the fourth ventricle, causing obstructive hydrocephalus. She underwent surgery again, and the tumor was totally removed. Histological findings showed mitotic cells and increased cellularity compared with the primary tumor, which was compatible with anaplastic transformation of PA with a MIB-1 index of 50%. Postoperatively, she was observed with best supportive care without postoperative adjuvant therapy. Nine months after the second operation, she died due to tonsillar herniation and obstructive hydrocephalus caused by a recurrent tumor. An autopsy was performed. CONCLUSION: It is extremely rare, as in the present case, that a cerebellar PA in an elderly patient recurs rapidly with anaplastic transformation, despite deferred postoperative adjuvant therapy including radiation and chemotherapy A novel molecular-targeted therapy is needed for anaplastic PA showing aggressive biological behavior.

In silico analysis identifies a putative cell-of-origin for BRAF fusion-positive cerebellar pilocytic astrocytoma.

Childhood cancers are increasingly recognized as disorders of cellular development. This study sought to identify the cellular and developmental origins of cerebellar pilocytic astrocytoma, the most common brain tumor of childhood. Using publicly available gene expression data from pilocytic astrocytoma tumors and controlling for driver mutation, a set of developmental-related genes which were overexpressed in cerebellar pilocytic astrocytoma was identified. These genes were then mapped onto several developmental atlases in order to identify normal cells with similar gene expression patterns and the developmental trajectory of those cells was interrogated. Eight known neuro-developmental genes were identified as being expressed in cerebellar pilocytic astrocytoma. Mapping those genes or their orthologs onto mouse neuro-developmental atlases identified overlap in their expression within the ventricular zone of the cerebellar anlage. Further analysis with a single cell RNA-sequencing atlas of the developing mouse cerebellum defined this overlap as occurring in ventricular zone progenitor cells at the division point between GABA-ergic neuronal and glial lineages, a developmental trajectory which closely mirrors that previously described to occur within pilocytic astrocytoma cells. Furthermore, ventricular zone progenitor cells and their progeny exhibited evidence of MAPK pathway activation, the paradigmatic oncogenic cascade known to be active in cerebellar pilocytic astrocytoma. Gene expression from developing human brain atlases recapitulated the same anatomic localizations and developmental trajectories as those found in mice. Taken together, these data suggest this population of ventricular zone progenitor cells as the cell-of-origin for BRAF fusion-positive cerebellar pilocytic astrocytoma.

Transient diabetes insipidus post endoscopic third ventriculostomy: Case report and literature review

BackgroundEndoscopic third ventriculostomy (ETV) is a procedure commonly used to relieve obstructive hydrocephalus. A very small percentage of patients suffers from transient or permanent hormonal disturbances following this procedure.Case Description.We report the case of a 19 years old woman with recurrent cerebellar pilocytic astrocytoma and moderate hydrocephalus. The patient underwent ETV followed by suboccipital craniotomy for resection of the lesion. Postoperatively, she suffered from polyuria and hypernatremia. Intravenous Desmopressin was given, and the patient recovered completely after few days. The patient was thought to have a transient diabetes insipidus from balloon overinflation during ETV and hypothalamic injury. ConclusionOverinflation of the balloon during ETV and subsequent hypothalamic injury can cause DI, a rare but potentially dangerous complication of this procedure. Postoperative surveillance and management of electrolytes disturbances is crucial to prevent any long term injury. ETV must be reconsidered if the prepontine cistern is not clearly patent to avoid complications.