PMC8541705_01
(A-D) First MRI. (A) Axial T2-weighted image shows homogeneous tumor tissue, mainly involving the left frontal and temporal lobe (black arrows), which is of isointense signal intensity compared with the cerebral cortex. Massive posthemorrhagic enlargement of the subdural space is visible on the left. (B and C) Diffusion-weighted images show a slight diffusion restriction as a sign of high cellularity. (D) T1-weighted image shows clots of methemoglobin (*). (E-G) Follow-up MRI at day 24. (E) T2-weighted image shows a substantial increase in the signal intensity of the tumor. (F and G) Diffusion-weighted images show decreasing diffusion restriction. (G) Tumor tissue is now partially hyperintense on apparent diffusion coefficient (ADC) compared with brain parenchyma. Imaging changes in E-G were interpreted as a change from high to lower cellularity. (H) At 5 months after diagnosis, only small, stable tumor residues could be found (black arrow).
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F1
At the age of 4 weeks, MRI showed a homogeneous tumor, with morphological signs of high-grade glioma, mainly involving the left frontal and temporal lobe, and a massive posthemorrhagic enlargement of the subdural space on the left (Figure 1A-D).
High-grade glioma with high cellularity, brisk mitotic activity, and microvascular proliferation without necrosis, H&E staining (A). Focal expression of glial fibrillary acidic protein (GFAP) (B), strong expression of MAP2 (C), negativity for IDH1 (R132H) (D), retained nuclear expression of ATRX (E), and proliferation index Ki-67 with an average of 20% (F) (scale bar 100 microm; magnification 100x).
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F2
The proliferation rate of tumor cells, estimated using the Ki-67 index, was high (~20%; Figure 2).
Methylation profile of the tumor (Sentrix ID: 204273190021_R02C01) in relation to the big reference dataset of tumors. tSNE visualization using the Fit-SNE algorithm, using the top 50 000 most differentially methylated CpG sites from the methylation arrays. More than 90 000 DNA methylation samples are represented, including over 60 000 brain tumors. The coloring of the reference groups is according to Capper et al. Nature 2018. This further shows that the tumor has the greatest similarity with the "Infantile Hemispheric Glioma" tumor group (IHG). The IHG group (colored in light purple) is circled with a red dashed line and labeled. The present case is marked with a black arrow, as shown in more detail on the zoomed-in region.
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F3
DNA methylation array classified the tumor as an infantile hemispherical glioma, with evidence of a CLIP2-MET fusion detected by next-generation sequencing (Figure 3).