case_images: PMC11828785_01
case_images: The preoperative MRI findings. A T1-weighted axial image shows a heterogeneous hypointense lesion with contact to the brainstem. B T2-weighted axial image shows an intermediate heterogeneous lesion with minimal perifocal edema and small cystic components. C Axial contrast-MRI with inhomogeneous moderate enhancement of the lesion. D Sagittal FLAIR sequence that demonstrates the cranio-caudal extension of the tumor and shows a minimal increase of FLAIR signal intensity. E, F Apparent diffusion coefficient (ADC) imaging and diffusion-weighted imaging show partly moderate restricted diffusion with multiple small cystic components with proportionately small areas with significant cerebral blood volume increase
case_images: 381_2025_6768_Fig1_HTML.jpg
case_images: PMC11828785_01_381_2025_6768_Fig1_HTML.jpg
case_images: Fig1
case_images: MRI revealed no further suspicious lesions. Medulloblastoma and high-grade ependymoma were the radiological differential diagnoses (Fig. 1).
case_images: The postoperative MRI findings in the same sequence of Fig. 1 and a total resection with no residual tumor
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case_images: PMC11828785_01_381_2025_6768_Fig2_HTML.jpg
case_images: Fig2
case_images: A circumscript glioma composed of round or cuboidal cells arranged around blood vessels in a pseudo-papillary pattern (A). Immunohistochemistry displays widespread and strong expression of EMA (B). The tumor cell nuclei are immunoreactive for Olig2 (C). The Ki67-proliferation index is elevated (D)
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case_images: PMC11828785_01_381_2025_6768_Fig3_HTML.jpg
case_images: Fig3
case_images: The primary histological findings suggested a proliferative active tumor with co-expression of epithelial membrane antigen (EMA), oligodendrocyte transcription factor (Olig2), and elevated Ki67-proliferation index (Fig. 3).
case_images: Evidence for a MN1-BEND2 fusion: Molecular inversion profile technique revealed an in-frame fusion of the MN1 gene at chromosome band 22q12.1 with BEND2 (above) at chromosome band Xp22.13 (below), which is characteristic of astroblastoma, MN1-altered
case_images: 381_2025_6768_Fig4_HTML.jpg
case_images: PMC11828785_01_381_2025_6768_Fig4_HTML.jpg
case_images: Fig4
case_images: However, the extended moleculo-histological examination 3 weeks later confirmed the diagnosis of an astroblastoma with MN1-alteration and unmethylated MGMT promoter methylation status (MGMT-STP27) (Fig. 4).