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Pilomyxoid astrocytoma (PMA) is a subtype of pilocytic astrocytoma (PA). PMA tends to exhibit a more aggressive course compared to PA. We present a case of a two-year-old male with a PMA in the suprasellar region who presented with developmental regression, loss of previously attained milestones such as the ability to hold his neck, walk, and talk, along with hypotonia in all four limbs. Serum cortisol and thyroid-stimulating hormone (TSH) levels were measured to rule out endocrine disturbances and were within normal limits. Magnetic resonance imaging (MRI) of the brain showed a solid lesion in the suprasellar region, extending into the pituitary and interpeduncular fossae, compressing the pituitary gland, and effacing the third ventricle, causing cerebrospinal fluid (CSF) flow obstruction and lateral ventricle dilation. The tumor appears hypointense on T1 and hyperintense on T2, with fluid-attenuated inversion recovery (FLAIR), peripheral contrast enhancement, and no calcification, consistent with PMA. The CSF analysis was negative for malignant cells. Histopathological examination revealed monomorphous bipolar and spindle cells in an angiocentric pattern with a myxoid background, without rosenthal fibers, mitoses, or eosinophilic granular bodies, consistent with PMA but not seen in PA. Immunohistochemistry showed strong positivity for glial fibrillary acidic protein (GFAP) and S100, with a Ki-67 index of 3-4%, indicating a low-grade tumor. The preferred treatment is surgical resection, but due to the tumor's deep location and potential long-term neurological effects, the parents opted against surgery. A ventriculoperitoneal shunt was placed to alleviate CSF flow, following which the child showed mild improvement in symptoms. Treatment of nonresectable astrocytomas was controversial, but gross total surgical resection offers better disease control. Chemotherapy is for patients with recurrence or where total resection of the tumor is not possible, and radiotherapy, though the long-term disease control is good, has a variable visual outcome.

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Pilomyxoid astrocytoma [PMA] is a rare, recently described variant of pilocytic astrocytoma with unique clinical and histopathological characteristics. It typically affects the optico-chiasmatic and hypothalamic region in infants and young children. Though the pilocytic astrocytoma is the commonest tumor of the optic nerve, pilomyxoid astrocytoma arising from the intraorbital part of the optic nerve is extremely rare. To the best of our knowledge, only one case of introrbital optic nerve pilomyxoid astrocytoma has been described in the English literature. We report two cases of pilomyxoid astrocytoma arising from the intraorbital optic nerve, diagnosed on intraoperative squash smear cytology and later confirmed on histopathology. Like in other locations, optic nerve pilomyxoid astrocytoma behaves in an aggressive manner.

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Introduction: Pilocytic astrocytoma (PA) is one of the most common primary intracranial neoplasms in childhood with an overall favorable prognosis. Despite decades of experience, there are still diagnostic and treatment challenges and unresolved issues regarding risk factors associated with recurrence, most often due to conclusions of publications with limited data. We analyzed 499 patients with PA diagnosed in a single institution over 30 years in order to provide answers to some of the unresolved issues. Materials and Methods: We identified pilocytic astrocytomas diagnosed at the University of California, San Francisco, between 1989 and 2019, confirmed the diagnoses using the WHO 2021 essential and desirable criteria, and performed a retrospective review of the demographic and clinical features of the patients and the radiological, pathologic and molecular features of the tumors. Results: Among the patients identified from pathology archives, 499 cases fulfilled the inclusion criteria. Median age at presentation was 12 years (range 3.5 months - 73 years) and the median follow-up was 78.5 months. Tumors were predominantly located in the posterior fossa (52.6%). There were six deaths, but there were confounding factors that prevented a clear association of death to tumor progression. Extent of resection was the only significant factor for recurrence-free survival. Recurrence-free survival time was 321.0 months for gross total resection, compared to 160.9 months for subtotal resection (log rank, p <0.001). Conclusion: Multivariate analysis was able to identify extent of resection as the only significant variable to influence recurrence-free survival. We did not find a statistically significant association between age, NF1 status, tumor location, molecular alterations, and outcome. Smaller series with apparently significant results may have suffered from limited sample size, limited variables, acceptance of univariate analysis findings as well as a larger p value for biological significance. PA still remains a predominantly surgical disease and every attempt should be made to achieve gross total resection since this appears to be the most reliable predictor of recurrence-free survival.

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A ventriculoperitoneal (VP) shunt is a commonly used mechanical device indicated for congenital and acquired hydrocephalus in children. Although VP shunt failure is not uncommon, the symptomatology and cause of failure can vary. In this case, we describe intestinal obstruction in a three-year-old Caucasian female with a history of Pilomyxoid Astrocytoma and VP shunt placement for the management of hydrocephalus. Surgical exploration revealed ischemia of the terminal ileum secondary to VP shunt tubing-induced adhesions requiring bowel resection. A secondary VP shunt infection due to Enterococcus faecalis was also noted. Our case highlights a unique presentation of intestinal obstruction and infection that should serve to increase provider suspicion when evaluating patients presenting with abdominal distention and pain with presence of a VP shunt.

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Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

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Background: Pilocytic Astrocytoma (PA) is the most common pediatric brain tumors. PAs are slow-growing tumors with high survival rates. However, a distinct subgroup of tumors defined as pilomyxoid astrocytoma (PMA) presents unique histological characteristics and have more aggressive clinical course. The studies on genetics of PMA are scarce. Methods: In this study, we report one of the largest cohort of pediatric patients with pilomyxoid (PMA) and pilocytic astrocytomas (PA) in Saudi population providing a comprehensive clinical picture, retrospective analysis with long-term follow-up, genome-wide copy number changes, and clinical outcome of these pediatric tumors. We examined and compared genome-wide copy number aberrations (CNAs) and the clinical outcome of the patients with PA and PMA. Results: The median progression free survival for the whole cohort was 156 months and it was 111 months for the PMA, however, not statistically significantly different between the groups (log-rank test, P = 0.726). We have identified 41 CNAs (34 gains and 7 losses) in all tested patients. Our study yielded the previously reported KIAA1549-BRAF Fusion gene in over 88% of the tested patients (89% and 80% in PMA and PA, respectively). Besides the fusion gene, twelve patients had additional genomic CNAs. Furthermore, pathway and gene network analyses of genes in the fusion region revealed alterations in retinoic acid mediated apoptosis and MAPK signaling pathways and key hub genes that may potentially be involved in tumor growth and progression, including BRAF, LUC7L2, MKRN1, RICTOR, TP53, HIPK2, HNF4A, POU5F, and SOX4. Conclusion: Our study is the first report of a large cohort of patients with PMA and PA in the Saudi population that provides detailed clinical features, genomic copy number changes, and outcome of these pediatric tumors and may help better diagnosis and characterization of PMA.

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Pilomyxoid astrocytoma (PMA) is a rare variant of astrocytoma that is usually present in the hypothalamic and chiasmatic areas in the paediatric population. PMA shares many similar histopathological features to Pilocytic astrocytoma (PA), with some notable differences in its radiological and histopathological findings. On the contrary, PMA has been reported to behave more aggressively in its clinical progression than PA. Here, we describe a rare case of PMA in a 25-year-old female involving the temporal lobe, presenting with recurrent partial seizures. To our knowledge, this is the first reported case of PMA presenting in the temporal lobe in an adult female with an atypical location of the tumour, uncommon age group, and unusual radiological features being unique in this case report.

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Pilomyxoid astrocytoma is a subtype of pilocytic astrocytoma that is described as a grade 1 tumour in the 2022 WHO classification of central nervous system tumours. It occurs predominantly in the hypothalamic region in infants. Although the histological features of pilomyxoid astrocytomas are well documented, few reports are available in the literature regarding cytological findings. Here we describe the squash cytological features of a case of pilomyxoid astrocytoma along with a summary of prior published cases. Smears for this type of tumour tend to be more cellular, with piloid cells arranged in an angiocentric pattern without Rosenthal fibres or eosinophilic granular bodies. A blue myxoid substance may be present in the background.

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The case is presented of a girl diagnosed with obstructive hydrocephalus due to pilomyxoid astrocytoma, which required a ventriculoperitoneal shunt (VPS) at the age of 5 years and 10 months. Two months later, magnetic resonance imaging of the brain did not show ventriculomegaly or other signs of increased intracranial pressure. At the age of 6 years and 2 months, a rapid onset of bilateral visual acuity loss developed and she was diagnosed with slit ventricle syndrome. Despite valve revisions of the VPS, she developed an abrupt decline of visual acuity to hand motion at 10 cm. Fundus examination revealed bilateral optic atrophy. She did not report any other systemic symptoms suggesting increased intracranial pressure, such as headache, nausea, vomiting, lethargy, irritability, or altered levels of consciousness.

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Se describe una niña con hidrocefalia obstructiva por un astrocitoma pilomixoide, que requirió implantar una derivación ventrículo-peritoneal (DVP) a los 5 años y 10 meses de edad. Dos meses después, la resonancia magnética cerebral no mostró ventriculomegalia ni otros signos de aumento de la presión intracraneal. A la edad de 6 años y 2 meses desarrolló una rápida disminución de la agudeza visual bilateral siendo diagnosticada de síndrome de colapso ventricular. A pesar de las revisiones valvulares de la DVP, se produjo una disminución abrupta de la agudeza visual a movimientos de mano a 10cm. El examen del fondo de ojo reveló atrofia óptica bilateral. No refirió otros síntomas sistémicos que sugirieran un aumento de la presión intracraneal, como dolor de cabeza, náuseas, vómitos, letargia, irritabilidad o niveles alterados de conciencia.

The case is presented of a girl diagnosed with obstructive hydrocephalus due to pilomyxoid astrocytoma, which required a ventriculoperitoneal shunt (VPS) at the age of 5 years and 10 months. Two months later, magnetic resonance imaging of the brain did not show ventriculomegaly or other signs of increased intracranial pressure. At the age of 6 years and 2 months, a rapid onset of bilateral visual acuity loss developed and she was diagnosed with slit ventricle syndrome. Despite valve revisions of the VPS, she developed an abrupt decline of visual acuity to hand motion at 10cm. Fundus examination revealed bilateral optic atrophy. She did not report any other systemic symptoms suggesting increased intracranial pressure, such as headache, nausea, vomiting, lethargy, irritability, or altered levels of consciousness.

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The Pilomyxoid is rare tumor in elderly population, in addition to the occurrence of an isolated lesion in spinal cord is extremely rare in non-pediatric population. Taking biopsy and subtotal resection is the starting point in essential approach for the treatment. After defining the histopathological nature of the tumor and specified that is Pilomyxoid, the next step is the combination of reoperation and adjuvant therapy.

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Pilomyxoid astrocytoma (PMA), a distinct clinico-histopathological entity in the World Health Organization classification 2007, tends to be locally aggressive, with higher chance of leptomeningeal dissemination, recurrence, and poor prognosis. PMA is generally seen in young children and tend to occur in the hypothalamic-chiasmatic region. Their presence in other parts of the brain in the non pediatric age group is uncommon. To the best of our knowledge we are presenting first case of cerebellar PMA associated with neurofibromatosis 1 (NF1) in a 40-year- old female, with immunohistochemical study.

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BACKGROUND: Pilomyxoid astrocytomas are an aggressive subtype of astrocytoma, not graded by WHO, frequently located in hypothalamic/chiasmatic region, affecting diencephalic structures, and characterized by shorter survival and high recurrence rates. Pilomyxoid astrocytoma management remains controversial, with pathologic tissue diagnosis and relief of mass effect being the main goals of surgery while avoiding treatment-related morbidity, including vision loss, panhypopituitarism, and hypothalamic dysfunction. Chemotherapy (typically vincristine and carboplatin) in all pediatric patients and radiation therapy in pediatric patients over 5 years of age are used for treatment. METHODS: We report clinical presentation, surgical management, and whole exome sequencing results in a pediatric patient with the subtotally resected pilomyxoid astrocytoma. RESULTS: We identified two somatic activating missense mutations affecting FGFR1, including FGFR1 p.K656E and FGFR1 p.V561M. While the former is a known hotspot mutation that is both activating and transforming, the latter has been described as a gatekeeper mutation imparting resistance to FGFR inhibitors. Interestingly, both mutations were present with similar variant allele frequency within the tumor. CONCLUSION: Similar variant allele frequencies of FGFR1 p.K656E and FGFR1 p.V561M mutations in our patient's tumor suggest that these mutations may have occurred at similar time points. Use of FGFR inhibitors in addition to STAT3 or PI3K/mTOR inhibition may prove a useful strategy in targeting our patient's pilomyxoid astrocytoma.

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The case is presented of a girl diagnosed with obstructive hydrocephalus due to pilomyxoid astrocytoma, which required a ventriculoperitoneal shunt (VPS) at the age of 5 years and 10 months. Two months later, magnetic resonance imaging of the brain did not show ventriculomegaly or other signs of increased intracranial pressure. At the age of 6 years and 2 months, a rapid onset of bilateral visual acuity loss developed and she was diagnosed with slit ventricle syndrome. Despite valve revisions of the VPS, she developed an abrupt decline of visual acuity to hand motion at 10cm. Fundus examination revealed bilateral optic atrophy. She did not report any other systemic symptoms suggesting increased intracranial pressure, such as headache, nausea, vomiting, lethargy, irritability, or altered levels of consciousness.

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PURPOSE: Pilocytic (PA) and pilomyxoid astrocytomas (PMA) are related low-grade tumors which occur predominantly in children. PMAs have a predilection for a supratentorial location in younger children with worse outcomes. However, the two have similar imaging characteristics. Quantitative MR sequences such as dynamic susceptibility contrast (DSC) perfusion and diffusion (DWI) were assessed for significant differences between the two tumor types and locations. METHODS: A retrospective search for MRI with DSC and DWI on pathology-proven cases of PMA and PA in children was performed. Tumors were manually segmented on anatomic images registered to rCBV, K2, and ADC maps. Tumors were categorized as PA or PMA, with subclassification of supratentorial and infratentorial locations. Mean values were obtained for tumor groups and locations compared with Student's t test for significant differences with post hoc correction for multiple comparisons. ROC analysis for significant t test values was performed. Histogram evaluation was also performed. RESULTS: A total of 49 patients met inclusion criteria. This included 30 patients with infratentorial PA, 8 with supratentorial PA, 6 with supratentorial PMA, and 5 with infratentorial PMA. Mean analysis showed significantly increased rCBV for infratentorial PMA (2.39 ± 1.1) vs PA (1.39 ± 0.16, p = 0.0006). ROC analysis for infratentorial PA vs PMA yielded AUC = 0.87 (p < 0.001). Histogram analysis also demonstrated a higher ADC peak location for PMA (1.8 ± 0.2) vs PA (1.56 ± 0.28). CONCLUSION: PMA has a significantly higher rCBV than PA in the infratentorial space. DSC perfusion and diffusion MR imaging may be helpful to distinguish between the two tumor types in this location.

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Pilomyxoid astrocytoma (PMA) is a rare brain tumour generally located in the chiasmatic-hypothalamic region. In comparison to pilocytic astrocytoma, PMA has distinct histopathological features, aggressive clinical behaviour, a high recurrence rate, and early cerebrospinal fluid dissemination. Only 14 cases of PMA have been reported in the spinal cord since its pathological description in 1999. Here, we report the 15th case in a 3-year-old girl who was treated with chemoradiotherapy and followed up for 5 years. In this report, we also present a review of spinal PMA including treatment options and prognosis.

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OBJECTIVE: The choice of treatment modality for optic pathway gliomas (OPGs) is controversial. Chemotherapy is widely regarded as first-line therapy; however, subtotal resections have been reported for decompression or salvage therapy as first- and second-line treatment. The goal of this study was to further investigate the role and efficacy of resection for OPGs. METHODS: A retrospective chart review was performed on 83 children who underwent surgical treatment for OPGs between 1986 and 2014. Pathology was reviewed by a neuropathologist. Clinical outcomes, including progression-free survival (PFS), overall survival (OS), and complications, were analyzed. RESULTS: The 5- and 10-year PFS rates were 55% and 46%, respectively. The 5- and 10-year OS rates were 87% and 78%, respectively. The median extent of resection was 80% (range 30%-98%). Age less than 2 years at surgery and pilomyxoid features of the tumor were found to be associated with significantly lower 5-year OS. No difference was seen in PFS or OS of children treated with surgery as a first-line treatment compared with children with surgery as a second- or third-line treatment. Severe complications included new disabling visual deficit in 5%, focal neurological deficit in 8%, and infection in 2%. New hormone deficiency occurred in 22% of the children. CONCLUSIONS: Approximately half of all children experience a long-term benefit from resection both as primary treatment and as a second-line therapy after failure of primary treatment. Primary surgery does not appear to have a significant benefit for children younger than 2 years or tumors with pilomyxoid features. Given the risks associated with surgery, an interdisciplinary approach is needed to tailor the treatment plan to the individual characteristics of each child.

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Pilomyxoid astrocytomas (PMAs) are generally seen in young children and tend to occur in the hypothalamic-chiasmatic region. Their presence in other parts of the brain in the nonpediatric age group is uncommon. In addition, hemorrhage in such low-grade tumors is an occasional event. We describe a case of PMA that presented with spontaneous bleed in an atypical location (temporoparietal region) in an adult. A concise literature of the cases of PMA which were associated with bleed is also presented. Occasionally, low-grade tumors such as PMA may present with bleed. These benign looking neoplasms behave differently from the commonly occurring pilocytic astrocytomas (PAs) and should be considered as a differential. It is important to differentiate these from PA, as the management and prognosis differs.

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Pilomyxoid astrocytoma is a variant of pilocytic astrocytoma and the clinical, histological and molecular data point to a very close relationship as well as a more aggressive biological behavior for the former. WHO 2016 classification does not provide a specific grade for these neoplasms, but there is sufficient evidence in the literature that pilomyxoid astrocytoma has slightly worse prognosis than typical pilocytic astrocytoma. There is increasing evidence that in addition to the MAPK pathway alterations, pilomyxoid astrocytomas harbor genetic alterations that distinguish them from typical pilocytic astrocytoma.

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BACKGROUND: Pilomyxoid astrocytoma (PMA) is a variant of pilocytic astrocytomas but exhibits more aggressive behavior. Further, it is more prevalent in the hypothalamic/chiasmatic regions and is only rarely encountered in the thoracic spine. CASE DESCRIPTION: A 9-year-old male presented with severe spastic paraparesis (motor/sensory) attributed to a thoracic cord PMA and scoliosis. The magnetic resonance (MR) showed an intraaxial ill-defined expansile lesion with heterogeneous enhancement extending from the cervicothoracic junction to conus medullaris. A multilevel decompressive laminectomy was performed with restricted tumor debulking; an expansile duraplasty was also effected. Two years later, the patient has moderately improved and has not shown any symptom progression. CONCLUSION: We recommend the early performance of a thoracic MR in children with idiopathic scoliosis presenting with the onset of a significant spastic paraparesis.