Introduction:
Astroblastomas are rare neuroepithelial tumors that have emerged as a
new entity in the 2021 World Health Organization (WHO) classification of
tumors of the central nervous system (CNS), based on its peculiar
histopathologic features of “astroblastic pseudorosettes” andMeningioma 1 (MN1 ) altered molecular characterization
[1]. It comprises approximately 0.45%-2.8% of all glial tumors,
with the majority affecting children, adolescents, young adults, and
females disproportionately [2, 3]. Bailey and Cushing first
introduced the term “astroblastoma” in 1926, with Bailey and Bucy
further characterizing it through a series of 25 cases in 1930 [4,
5]. Its path to recognition as a discrete entity has been challenging
given its rare occurrence, unknown origin, and clinical behavior, as
well as overlapping features with astrocytomas and ependymomas [2,
6]. Astroblastomas tend to be well-circumcised mass localized to the
cerebral hemispheres though recent case reports have demonstrated its
rare presentation in the spinal cord in the absence of MN1alterations [7]. Astroblastic pseudorosettes are characterized by
cuboidal or columnar cells with varying perivascular acellular regions,
and vascular and perivascular hyalinization; features that can also be
observed with other gliomas including anaplastic astrocytoma and
glioblastoma [1-3, 8]. Therefore, prior to Strum and colleagues
discovery of CNS high-grade neuroepithelial tumor with MN1alteration (CNS HGNET-MN1) as a new entity based on modern DNA
methylation profiling of primitive neuroectodermal tumors of the CNS in
2016, astroblastomas were previously included under the category of
“other gliomas” in the 2016 WHO classification of tumors of the CNS
[9]. Currently, no clear histological features for grading
astroblastomas have been defined but they can be broadly categorized
into low-grade and high-grade with the latter fulfilling the following
parameters: increased cellularity, anaplastic nuclear pattern, high
mycotic index (> 5/10 high power fields), vascular
proliferation, necrosis with pseudopalisades, and MIB-1 proliferative
index between 6 and 22% [10].
Herein, we report a case of a 10-year-old girl with MN1 -altered
astroblastoma who interestingly also harbor an ataxia-telangiectasia
mutated (ATM) mutation discovered upon genome sequencing.