Patterns of care and survival outcomes in patients with astroblastoma: an individual patient data analysis of 152 cases

Radiology-Pathology and Surgical Correlation in Astroblastoma

Astroblastoma is a rare astrocytic glial neoplasm that affects mainly young girls, peaking between 10 and 30 years of age, with low- and high-grade manifestations. Imaging characteristics are well-described, but histopathologic and, more recently, molecular analysis is fundamental to establish the diagnosis, now based on MN1 alterations. We describe a case with typical imaging and histologic features of an MN1-altered astroblastoma.

A pediatric cerebral tumor with MN1 alteration and pathological features mimicking carcinoma metastasis: may the terminology "high grade neuroepithelial tumor with MN1 alteration" still be relevant?

INTRODUCTION

Astroblastoma, MN1-altered (old name: high-grade neuroepithelial tumor/HGNET with MN1 alteration) is a recently described central nervous system tumor mostly affecting pediatric patients and profoundly young girls. Differential pathological diagnoses of these tumors include ependymoma, pleomorphic xanthoastrocytoma, embryonal tumor with multilayered rosettes, meningioma, and even glioblastoma. As the treatment approaches to these tumors differ, it is essential to increase the awareness about these tumors in the neurosurgical community.

CLINICAL PRESENTATION

A 7-year-old female patient admitted with a 7-day history of headache, nausea, and vomiting. A contrasted MRI scan revealed a left parietal 4 × 4 × 5 cm mass with central necrosis and peripheral contrast enhancement. The tumor's histopathological findings were suggestive of a metastatic carcinoma with unknown primary, yet further genetic analysis revealed MN1 alteration. Peculiarly, the tumor pathomorphological features were not compatible with astroblastomas and exerted features strongly indicating a metastatic cancer; however, systemic PET and whole-body MRI failed to detect a primary malignancy.

OUTCOME AND CONCLUSIONS

Eighteen months after gross-total tumor resection, an in-field and out-field multifocal recurrence developed which required a second surgery and subsequent chemo-radiotherapy. The patient is doing well for 1 year after the second treatment regimen at the time of this report. Despite the final cIMPACT6 classification in 2020 advised to define all MN1 altered brain tumors as astroblastomas, there exist prognostic differences in MN1-altered tumors with and without morphological features of astroblastoma. Rare morphological variants of MN1-altered tumors shall be recognized for their future prognostic and clinical classification. HGNET with MN1 alteration seems still be a more proper definition of such malignancies as an umbrella term.

Well-differentiated Astroblastoma with Both Focal Anaplastic Features and a Meningioma 1 Gene Alteration

A 6-year-old female was incidentally found to have a brain tumor. Magnetic resonance imaging (MRI) demonstrated a gadolinium-enhanced mass in the left parietal lobe. We performed gross total resection with the assistance of fluorescent guidance by 5-aminolevulinic acid (5-ALA). A histological examination of the tumor specimen showed well-differentiated astroblastic features with focal anaplasia. Fluorescence in situ hybridization (FISH) revealed meningioma 1 (MN1) gene alteration and supported our diagnosis. She received local radiotherapy and oral temozolomide followed by maintenance temozolomide chemotherapy, and the tumor was well controlled without any neurological deficit for 27 months. Our case is considered to be valuable since it describes a patient who is diagnosed to have a well-differentiated astroblastoma with both focal anaplastic features and MN1 gene rearrangement. A larger study is warranted to establish evidence supporting the diagnosis and treatment of astroblastoma with molecular characteristic features. MN1 alteration will be a diagnostic marker for astroblastoma in the future.

Uncommon low-grade brain tumors

The 2016 World Health Organization (WHO) classification of primary central nervous system (CNS) tumors includes numerous uncommon (representing ≤1% of tumors) low-grade (grades I-II) brain neoplasms with varying clinical behaviors and outcomes. Generally, gross tumor or maximal safe resection is the primary treatment. Adjuvant treatments, though their exact role is unknown, may be considered individually based on pathological subtypes and a proper assessment of risks and benefits. Targetable mutations such as BRAF (proto-oncogene B-Raf), TRAIL (tumor necrosis factor apoptosis inducing ligand), and PDGFR (platelet derived growth factor receptor) have promising roles in future management.

Molecular Profiling Reclassifies Adult Astroblastoma into Known and Clinically Distinct Tumor Entities with Frequent Mitogen-Activated Protein Kinase Pathway Alterations

BACKGROUND

Astroblastoma (ABM) is a rare glial brain tumor. Recurrent meningioma 1 (MN1) alterations have been recently identified in most pediatric cases. Adolescent and adult cases, however, remain molecularly poorly defined.

MATERIALS AND METHODS

We performed clinical and molecular characterization of a retrospective cohort of 14 adult and 1 adolescent ABM.

RESULTS

Strikingly, we found that MN1 fusions are a rare event in this age group (1/15). Using methylation profiling and targeted sequencing, most cases were reclassified as either pleomorphic xanthoastrocytomas (PXA)-like or high-grade glioma (HGG)-like. PXA-like ABM show BRAF mutation (6/7 with V600E mutation and 1/7 with G466E mutation) and CD34 expression. Conversely, HGG-like ABM harbored specific alterations of diffuse midline glioma (2/5) or glioblastoma (GBM; 3/5). These latter patients showed an unfavorable clinical course with significantly shorter overall survival (p = .021). Mitogen-activated protein kinase pathway alterations (including FGFR fusion, BRAF and NF1 mutations) were present in 10 of 15 patients and overrepresented in the HGG-like group (3/5) compared with previously reported prevalence of these alterations in GBM and diffuse midline glioma.

CONCLUSION

We suggest that gliomas with astroblastic features include a variety of molecularly sharply defined entities. Adult ABM harboring molecular features of PXA and HGG should be reclassified. Central nervous system high-grade neuroepithelial tumors with MN1 alterations and histology of ABM appear to be uncommon in adults. Astroblastic morphology in adults should thus prompt thorough molecular investigation aiming at a clear histomolecular diagnosis and identifying actionable drug targets, especially in the mitogen-activated protein kinase pathway.

IMPLICATIONS FOR PRACTICE

Astroblastoma (ABM) remains a poorly defined and controversial entity. Although meningioma 1 alterations seem to define a large subset of pediatric cases, adult cases remain molecularly poorly defined. This comprehensive molecular characterization of 1 adolescent and 14 adult ABM revealed that adult ABM histology comprises several molecularly defined entities, which explains clinical diversity and identifies actionable targets. Namely, pleomorphic xanthoastrocytoma-like ABM cases show a favorable prognosis whereas high-grade glioma (glioblastoma and diffuse midline gliome)-like ABM show significantly worse clinical courses. These results call for in-depth molecular analysis of adult gliomas with astroblastic features for diagnostic and therapeutic purposes.

Posterior fossa astroblastoma in a child: a case report and a review of the literature

A 4-year-old girl presented to the hospital with a progressive headache, difficulty walking, and persistent daily vomiting for 3 weeks. Papilledema was observed on fundoscopic examination. A large left cerebellovermian tumor with "bubbly" appearance was discovered. Total removal of the tumor mass was performed, and a diagnosis of low-grade astroblastoma was made. Adjuvant radiotherapy was performed due to the risk of recurrence. The patient is disease-free and has been kept on close follow-up for 6 months. The occurrence of posterior fossa astroblastoma has been rarely reported in the literature. Thus, when a "bubby" appearance enhancing cystic solid tumor is located on the cerebellar hemisphere in a child, an astroblastoma should also be included in the differential diagnosis.

Extra-axial anaplastic astroblastoma in a 67-year-old woman

Astroblastoma is a rare glial neoplasia of the central nervous system. It is histologically defined by the presence of neoplastic cells with non- or slightly tapering processes arranged around blood vessels (astroblastic rosettes) and conventionally subdivided into well-differentiated and anaplastic. It commonly affects children and young adults, although cases and due to its superficial location in the brain cortex, it can mimic an extra-axial mass on magnetic resonance imagining. Herein, we describe a unique case of pure extra-axial anaplastic astroblastoma in an elderly woman. Awareness that astroblastoma may be also extra-axial and affect older subjects, may be helpful for its identification and differential diagnosis toward more common entities at this site and age of onset, and for appropriate therapeutic management as well.

Role of DNA Methylation Profile in Diagnosing Astroblastoma: A Case Report and Literature Review

Astroblastoma is a rare tumor of the central nervous system (CNS) with uncertain clinical behavior. Recently, DNA methylation profiling has been shown to provide a highly robust and reproducible approach for the classification of all CNS tumors across different age groups. By using DNA methylation profiling, a subset of CNS high-grade tumors with astroblastoma-like morphology characterized by the meningioma 1 gene (MN1) rearrangements, has been identified; they were termed “CNS high-grade neuroepithelial tumors with MN1 alteration” (CNS-HGNET-MN1). Here, we describe a case of CNS-HGNET-MN1 diagnosed by DNA methylation profiling, using Illumina Infinium HumanMethylationEPIC BeadChip (EPIC), that offers the opportunity to conduct a brief literature review. The patient presented with an episode of partial seizures involving the right hemisoma. A gross total resection was performed. No other treatment was proposed in light of the histological and molecular findings. After 21 months, the patient is disease-free in good clinical conditions. Also in view of this case, we recommend DNA-methylation profiling as an important tool for diagnosis and more effective patient stratification and management.

Astroblastoma in a Young Female Patient: A Case Report and Literature Review of Clinicopathological, Radiological and Prognostic Characteristics and Current Treatment Strategies

Astroblastoma is an uncommon glial tumor with predominant manifestation in the young age. Herein, we report a case of 18-year-old astroblastoma female patient who presented with history of two months headache. Magnetic resonance imaging (MRI) of the brain demonstrated well circumscribed, intra-axial abnormal signal intensity lesion (size=5×4 cm²) in the right parieto-occipital region of the brain. The patient underwent complete surgical resection of the gross tumor, as confirmed by an early post-surgical MRI (i.e., within 24 hours of surgery). Histopathological examination revealed neoplastic lesion exhibiting perivascular pseudo-rosettes with centrally hyalinized blood vessel and focal nuclear pleomorphism. Immunohistochemistry staining illustrated reactivity for glial fibrillary acidic protein and integrase interactor 1 (INI-1). These features rendered the diagnosis of astroblastoma. A comprehensive review of the current literature to summarize the clinicopathological and radiological characteristics, prognostic factors and current treatment strategies of astroblastomas is also presented. Our study would expand the pool of this uncommon tumor towards its better understanding and optimal treatment.