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case_images: Brain MRI (sagittal T2 + C). Preoperative MRI shows a posterior fossa tumor (green arrows).
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case_images: F1
case_images: A brain MRI with contrast enhancement revealed a posterior fossa tumor with invasion into the lateral and third ventricles, called obstructive hydrocephalus (Figure 1).
case_images: Brain MRI (axial T2 + C). Postoperative changes, pathologic contrast accumulation in the walls of the resection cavity, and residual tumor in the vermis (green arrows).
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case_images: F2
case_images: A postoperative brain and spinal MRI with contrast enhancement was performed 48 h after surgery. A brain MRI showed hydrocephalus, residual tumor in the vermis, patterns of restricted diffusion, and pathological contrast accumulation in the walls of the resection cavity up to 1 mm, in the pia mater on the back of the brain stem, and the area of the right and left lateral apertures (Figures 2, 3).
case_images: Brain MRI (coronal T2 + C). Postoperative changes, pathologic contrast accumulation in the walls of the resection cavity, and residual tumor in the vermis (green arrows).
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case_images: F3
case_images: A postoperative brain and spinal MRI with contrast enhancement was performed 48 h after surgery. A brain MRI showed hydrocephalus, residual tumor in the vermis, patterns of restricted diffusion, and pathological contrast accumulation in the walls of the resection cavity up to 1 mm, in the pia mater on the back of the brain stem, and the area of the right and left lateral apertures (Figures 2, 3).
case_images: Spinal cord MRI (sagittal T2 + C). Thickening of the dura mater and intense contrast accumulation along the whole spine (green arrows).
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case_images: F4
case_images: Spinal MRI with contrast enhancement revealed a thickening of the shell-like dura mater up to 2-4 mm, intensive contrast accumulation along the whole spine, and irregular contrast accumulation of the pia mater (Figure 4).
case_images: Positive synaptophysin staining confirms the neuronal origin of the tumor. IHC with synaptophysin, magnification x200.
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case_images: F5
case_images: The rate of the Ki-67 proliferation index was 20% (Figures 5, 6).
case_images: Positive GFAP staining underlining perivascular pseudorosettes. IHC with GFAP, magnification x200.
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case_images: F6
case_images: The rate of the Ki-67 proliferation index was 20% (Figures 5, 6).
case_images: Morphologic picture of high-grade glioma. Hematoxylin and eosin staining, magnification x300.
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case_images: F7
case_images: Cells were polymorphic with an oligodendro-like morphology with a round nucleus and an optically scant cytoplasm, predominantly with high mitotic activity (Figure 7).
case_images: Positive cytoplasmic, but not nuclear staining for beta-catenin, confirming that the sample is not WNT-activated medulloblastoma. IHC with beta-catenin, magnification x200.
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case_images: F8
case_images: IHC analysis revealed positive cytoplasmatic beta-catenin, S100, GFAP, weak-positive p53, and negative CD34, OTX2, NSE, and chromogranin A staining (Figures 8, 9).
case_images: Positive nuclear staining for p53 and what might be observed in high-grade gliomas. IHC with p53, magnification x180.
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case_images: F9
case_images: IHC analysis revealed positive cytoplasmatic beta-catenin, S100, GFAP, weak-positive p53, and negative CD34, OTX2, NSE, and chromogranin A staining (Figures 8, 9).
case_images: Perivascular pseudorosettes (typical of ependymoma). Hematoxylin and eosin staining, magnification x160.
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case_images: F10
case_images: Dense-packed cells, mitosis, and structures resembled perivascular rosettes, and areas of small cells with astrocytic differentiation were described (Figure 10).
case_images: Focal weak-positive staining of neurofilaments may be seen in a well-defined tumor. IHC with NF, magnification x140.
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case_images: F11
case_images: IHC analysis revealed positive staining for GFAP, focal EMA expression, and a high Ki-67 index, which could be attributed to the young age of the patient (Figures 11-13).
case_images: High Ki-67 proliferation index. IHC with Ki-67, magnification x170.
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case_images: F12
case_images: IHC analysis revealed positive staining for GFAP, focal EMA expression, and a high Ki-67 index, which could be attributed to the young age of the patient (Figures 11-13).
case_images: Focal EMA staining in tumor cell cytoplasm. IHC with EMA, magnification x400.
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case_images: F13
case_images: IHC analysis revealed positive staining for GFAP, focal EMA expression, and a high Ki-67 index, which could be attributed to the young age of the patient (Figures 11-13).
case_images: Chromosome profile derived from tumor DNA methylation. Amid a signal scatter, a KIAA::BRAF fusion is suspected (suspected peak at the 7q34 locus).
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case_images: F14
case_images: The analytical results using v11b4 were interpreted as methylation class low-grade glioma and subclass posterior fossa pilocytic astrocytoma, whereas the analytical results using v12.5 were interpreted as infratentorial pilocytic astrocytoma (Figures 14, 15).
case_images: Electropherogram obtained from direct Sanger sequencing shows BRAF wild-type and absence of mutations.
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case_images: F15
case_images: The analytical results using v11b4 were interpreted as methylation class low-grade glioma and subclass posterior fossa pilocytic astrocytoma, whereas the analytical results using v12.5 were interpreted as infratentorial pilocytic astrocytoma (Figures 14, 15).