Adult pilomyxoid astrocytoma presenting in the temporal lobe

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.

Benign Glioma

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.

Cytological Features in Pilomyxoid Astrocytoma: A Case Report with Summary of Prior Published Cases

Pilomyxoid astrocytoma is a subtype of pilocytic astrocytoma described as grade 1 tumour in the WHO classification of CNS tumors, 2022. It occurs preferentially in the hypothalamic region in infants. Although the histological features of pilomyxoid astrocytomas are well documented, there is sparse literature available on the cytological findings of the same. Here we describe the squash cytological features of a case of pilomyxoid astrocytoma along with a summary of prior published cases. The smears of this tumour tend to be more cellular with piloid cells arranged in an angiocentric pattern without Rosenthal fibres or eosinophilic granular bodies. The background can have blue myxoid substance.

Visual acuity loss and sixth nerve palsy as the only manifestations of slit ventricle syndrome

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.

Visual acuity loss and sixth nerve palsy as the only manifestations of slit ventricle syndrome

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.

Thoracolumbar pilomyxoid astrocytoma concomitant with spinal scoliosis: A case report and literature review

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.

Differentiation of pilocytic and pilomyxoid astrocytomas using dynamic susceptibility contrast perfusion and diffusion weighted imaging

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.

Spinal Pilomyxoid Astrocytoma

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.

Posterior fossa pilomyxoid astrocytoma with spontaneous hemorrhage in pediatric patients

OBJECT

The tumor described in this report was unique because of its involvement with a posterior fossa spontaneous hemorrhage in a pediatric patient; such a case has never been previously described in cases of pilomyxoid astrocytomas and also rarely found in those of pilocytic astrocytomas.

METHODS

This report studied a rare case of posterior fossa pilomyxoid astrocytoma (PMA) with critical and dangerous spontaneous hemorrhage. A 7-year-old girl appeared at the outpatient clinic with sudden headache and vomiting.

RESULTS

The patient underwent gross total tumor resection via suboccipital Medline approach, and no evidence of residual or recurrent tumor was found on magnetic resonance images at two follow-up examinations which were respectively conducted 1 and 5 months after resection.

CONCLUSION

In this report, the authors reviewed the literature and discussed the clinical features and treatment of pilomyxoid astrocytoma. It is important to distinguish this tumor variant from the more indolent pilocytic astrocytoma.

Fluorescence guided resection with 5-aminolevulinic acid of a pilomyxoid astrocytoma of the third ventricle

Fluorescence-guided resection with 5-aminolevulinic acid has been shown to be useful in the resection of certain brain tumors other than high grade gliomas, facilitating the intraoperative differentiation of neoplastic tissue. The technique enables the surgeon to ensure that no tumor fragments remain, thereby achieving higher rates of complete resection. Tihan first described pilomyxoid astrocytomas in 1999. They are currently classified as grade II astrocytoma according to the WHO classification system and, because of their tendency to recur and their dissemination through the cerebrospinal fluid pathways, they are considered to be more aggressive than pilocytic astrocytoma. As a result, management of these tumors must be more aggressive, always aiming for complete macroscopic resection whenever possible. In this article, we present a case of pilomyxoid astrocytoma of the third ventricle in which the use of fluorescence-guided resection with 5-ALA facilitated complete resection. Imaging tests performed after five years revealed no signs of recurrence and no adjuvant radiotherapy or chemotherapy was required. This article also comprises a review of the literature concerning the characteristics and management of this tumor, which was recently considered to be a different histopathological entity.

Single-Agent Carboplatin for a Rare Case of Pilomyxoid Astrocytoma of the Spinal Cord in an Adult with Neurofibromatosis Type 1

INTRODUCTION

Pilomyxoid astrocytoma (PMA) is a rare and more aggressive variant of pilocytic astrocytoma, which usually affects young children and is most often located in the hypothalamic/chiasmatic region. The association of PMA with underlying genetic disorders is not well known.

METHODS

We identified a 23-year-old woman with a PMA of the spinal cord who was simultaneously diagnosed with neurofibromatosis type 1. Diagnosis of neurofibromatosis type 1 was made clinically and confirmed with genetic testing that revealed a heterozygous one-amino-acid deletion (c.2970-2972 delAAT) in exon 17 of the NF1 gene, which is correlated with a milder phenotype. The patient underwent a partial surgical resection of the spinal cord tumor followed by adjuvant carboplatin 560 mg/m² every 4 weeks. Radiation was avoided due to risks associated with neurofibromatosis type 1.

RESULTS

At the 11-month follow-up, the patient maintained a partial radiographic response as well as complete resolution of her neurologic deficits.

CONCLUSION

To our knowledge, this is the first reported case of an adult patient with neurofibromatosis type 1 and a spinal cord PMA. Single-agent carboplatin was effective and well-tolerated.

Spontaneous intratumoural and intraventricular haemorrhage associated with a pilomyxoid astrocytoma in the hypothalamic/chiasmatic region

Pilomyxoid astrocytoma (PMA) is a rare, low-grade glioma that is recognised as a variant of pilocytic astrocytoma. There have been few reports on this pathologic entity presenting with spontaneous haemorrhage. In this study, we report a rare case of PMA in the hypothalamic/chiasmatic region presenting with intratumoural and intraventricular haemorrhage. An external ventricular drain was urgently inserted. A ventriculo-peritoneal shunt (VP) was undergone 4weeks thereafter. The patient received fractionated Gamma Knife radiosurgery in another hospital 3weeks after the VP shunt. Three months later, subtotal resection of the tumour was performed in our hospital via a pterional approach. The pathological diagnosis was PMA. Postoperatively, no adjuvant therapy was given, and the neurologic deficits were improved. However, the presentation of endocrine deficits remained. Notably, PMAs in the hypothalamic/chiasmatic region presenting with massive intratumoural and intraventricular haemorrhage may result in a severe condition and long-term impairment of endocrine function. Long-term follow-up is required to monitor the recurrence of the tumour and endocrinopathy.

Whole Chromosome 7 Gain Predicts Higher Risk of Recurrence in Pediatric Pilocytic Astrocytomas Independently From KIAA1549-BRAF Fusion Status

The most frequent genetic alteration identified in pediatric pilocytic astrocytomas and pilomyxoid variant is the KIAA1549-BRAF fusion, which typically results from a 2.0 Mb tandem duplication in chromosome band 7q34. Less frequent abnormalities include fusion genes,BRAF, FGFR, KRAS, and NF1 point mutations, and whole chromosome gains. To correlate genetic alterations with clinical course data, we retrospectively analyzed the tumors with pilocytic and pilomyxoid histology of a cohort of 116 pediatric patients, aged 5 months to 23 years. Gross total resection was associated with a decreased risk of recurrence (p = 0.001), supporting previous findings that complete tumor excision correlates with long-term and disease-free survival. We found no significant association between recurrence rate and the presence of the KIAA1549-BRAF fusion or BRAF mutation (p = 0.167). Interestingly, gain of whole chromosome 7 (WC7) was associated with a 4.7-fold increased risk of tumor recurrence, even after adjusting for surgical status (p = 0.025), and other genetic alterations. Using fluorescence in situ hybridization, we demonstrated that when WC7 gain accompanies the KIAA1549-BRAF fusion, the fusion likely arises first. This study highlights the utility of genetic studies for risk assessment of pilocytic and pilomyxoid astrocytomas, which may impact treatment selections.

SOX10 Distinguishes Pilocytic and Pilomyxoid Astrocytomas From Ependymomas but Shows No Differences in Expression Level in Ependymomas From Infants Versus Older Children or Among Molecular Subgroups

SOX10 is important in nonneoplastic oligodendroglial development, but mRNA transcripts and protein expression are identified in a wider variety of CNS glial neoplasms than oligodendrogliomas. We previously demonstrated high levels of SOX10 mRNA and protein in pilocytic astrocytomas (PAs) but not ependymomas (EPNs). We now extend these studies to investigate subsets of these 2 tumors that affect infants, pilomyxoid astrocytomas (PMAs) and infant (<1 year) ependymomas (iEPNs). By gene expression microarray analysis, we found that iEPNs and all EPNs in older children showed very low SOX10 expression levels, on average 7.1-fold below normal control tissues. EPN groups showed no significant difference in SOX10 expression between iEPN and EPN. PAs/PMAs had 24.1/29.4-fold higher transcript levels, respectively, than those in normal tissues. Using immunohistochemical analysis of adult, pediatric, and infantile EPNs and of PAs/PMAs, we found that EPNs from multiple anatomical locations and both age groups (n = 228) never showed 3+ diffuse nuclear immunostaining for SOX10; the majority were scored at 0 or 1+. Conversely, almost all pediatric and adult PAs and PMAs (n = 47) were scored as 3+. These results suggest that in select settings, SOX10 immunohistochemistry can supplement the diagnosis of PMA and PA and aid in distinguishing them from EPNs.

Pilomyxoid astrocytoma in the adult cerebellum

Pilomyxoid astrocytoma (PMA) is a recently recognised World Health Organization (WHO) Grade II tumour that was previously characterised as a subtype of the WHO Grade I pilocytic astrocytoma (PA). PMA has a histological appearance distinct from PA and a poorer prognosis due to its greater propensity for local recurrence and cerebrospinal dissemination. Although originally considered a paediatric tumour involving mainly the hypothalamic and chiasmatic region, reports of the lesion occurring in the adult population and other areas of the neuroaxis are emerging. We review the literature on PMA within the adult population and present the first case of PMA in the cerebellum of an adult female.

A clinicopathologic study of diencephalic pediatric low-grade gliomas with BRAF V600 mutation

Among brain tumors, the BRAF (V600E) mutation is frequently associated with pleomorphic xanthoastrocytomas (PXAs) and gangliogliomas (GGs). This oncogenic mutation is also detected in ~5 % of other pediatric low-grade gliomas (LGGs) including pilocytic astrocytomas (PAs) and diffuse astrocytomas. In the current multi-institutional study of 56 non-PXA/non-GG diencephalic pediatric LGGs, the BRAF (V600) mutation rate is 36 %. V600-mutant tumors demonstrate a predilection for infants and young children (<age 3) and have a higher tendency for multicentricity. On neuroimaging, BRAF (V600)-mutant tumors appear as nodular, yet infiltrative contrast-enhancing masses. Morphologic examination reveals a monophasic, predominantly compact and partially infiltrative architecture. Due to the lack of classic morphologic features associated with PAs, pilomyxoid astrocytomas (PMAs), or diffuse astrocytomas, 75 % of the BRAF (V600)-mutant tumors could not be definitively classified on initial histopathologic evaluation. At a median follow-up of 55 months, the 5-year progression-free survival (PFS) rate for BRAF (V600)-mutant diencephalic low-grade astrocytomas (LGAs) was 22 ± 12 %, shorter than BRAF (V600)-WT PAs (52 ± 13 %) but higher than PMAs (10 ± 6 %). Of note, long-term PFS was observed in several adolescent patients with BRAF (V600)-mutant tumors. In children aged 0-12 years, 5-year PFS rate and median PFS in BRAF (V600)-mutant LGAs are 9 ± 9 % and 19 months (95 % CI 3-37 months), respectively. The PFS is comparable to that in BRAF (V600)-WT PMAs (5-year PFS rate: 10 ± 9 %; median PFS: 15 months, 95 % CI 3-32 months; p = 0.96) and significantly shorter than BRAF (V600)-WT PAs (5-year PFS rate: 46 ± 13 %; median PFS: 51 months, 95 % CI 20-∞ months; p < 0.05). In summary, diencephalic BRAF (V600)-mutant pediatric LGAs are associated with unique clinicopathologic features and have a more aggressive clinical course, especially in children under age 13. The low rate of CDKN2A deletion also suggests that these tumors are molecularly distinct from secondary pediatric high-grade gliomas.

Posterior fossa tumors in infants and neonates

INTRODUCTION

Management of posterior fossa tumors in infants and neonates is challenging. The characteristics of the young babies make surgery very difficult, sometimes precluding a safe complete removal.

METHODS

A review of the literature was undertaken to examine the incidence, histology, surgical aspects, and prognosis of posterior fossa tumors in the first year of life. Therapeutical strategies of the most frequent tumor types are also discussed in detail.

RESULTS

Histology is dominated by tumors with aggressive behavior, such as medulloblastomas, atypical teratoid/rhabdoid tumors, and anaplastic ependymomas. The most important surgical considerations in small children are the small circulating blood volume; the poor thermoregulation; and incomplete maturation of the brain, of the skull, and of the soft tissue. Treatment toxicity is inversely related to the age of the patients. Radiation therapy is usually considered as contraindicated in young children, with few exceptions. Proton therapy is a promising tool, but access to this kind of treatment is still limited. The therapeutic limitations of irradiation render resection of this tumor and adjuvant chemotherapy often the only therapeutic strategy in many cases.

CONCLUSIONS

The overall prognosis remains dismal because of the prevalent aggressive histologies, the surgical challenges, and the limitations of adjuvant treatment. Nevertheless, the impressive improvements in anesthesiology and surgical techniques allow, in the vast majority of the cases, complete removal of the lesions with minor sequelae in high-volume referral pediatric centers.

Pilomyxoid astrocytoma of the cerebellum with Williams syndrome: a case report

CASE REPORT

A 3-year-old boy with Williams syndrome associated with supravalvular aortic stenosis was admitted to our hospital with disturbance of consciousness and a 2-month history of truncal ataxia. T1-weighted magnetic resonance imaging with contrast medium showed a heterogeneously enhanced tumor in the right cerebellum with severe hydrocephalus. The patient underwent tumor resection via suboccipital craniotomy. At the end of resection of the tumor, sudden cardiac arrest occurred after ST segment elevation. Despite immediate cardiopulmonary resuscitation, the patient died. Histological examination of the cerebellar tumor revealed that the tumor consisted of monomorphous bipolar spindle cells on a background of myxoid matrix, and angiocentric arrangement without Rosenthal fibers or eosinophilic granular body. The final diagnosis was pilomyxoid astrocytoma.

CONCLUSION

This case of Williams syndrome with cerebellar pilomyxoid astrocytoma suggests the importance of investigation of the development of brain tumors and occurrence of intraoperative cardiac arrest associated with Williams syndrome.

Pilomyxoid astrocytoma in cerebellum

Pilomyxoid astrocytoma is a new identified variant type of pilocytic astrocytoma, and typically locates in the hypothalamic and chiasmatic region. Herein, we reported a nine-year-old boy with pilomyxoid astrocytoma in the cerebellum. MRI scanning showed a tumor involved the cerebellar vermis, tonsil, the forth ventricle and brainstem. It was homogeneous isointensity on T1WI, relative hyper-intensity on T2WI, hyper-intensity on fluid attenuated inversion recovery (FLAIR) images, and uniform enhancement on contrast T1WI. The tumor was sub-totally removed and was proved histologically to be pilomyxoid astrocytoma. Follow-up at the 5th month, MRI showed the residual tumor enlarged at the brainstem. The patient survived 10 months after the operation, and finally died of respiration failure resulting from brainstem dysfunction.

Juvenile pilomyxoid astrocytoma in the opticohypothalamus

Pilomyxoid astrocytoma (PMA) is a newly recognized variant of a pilocytic astrocytoma. This report describes a case of a pilomyxoid astrocytoma that occurred in the opticohypothalamus. The patient was a 18-year-old girl who complained decreased visual acuity and visual field over a period of two years. Magnetic resonance imaging (MRI) showed an irregular lobulated tumor with heterogeneous enhancement at the suprasellar region involving the hypothalamus. The mass was partially removed via the subfrontal approach. Its pathology was confirmed to be PMA. Adjuvant chemotherapy with cisplatin and vincristine was started following tumor resection. After four cycles, the mass showed a partial response to the chemotherapy. Although long-term outcome is yet to be determined, the administration of combined cisplatin and vincristine treatment seems to be an effective regimen for a pilomyxoid astrocytoma.