case_images: PMC9906127_01
case_images: AX 3DT1 native MRI of the brain showing a cystic tumor formation in the left cerebellar hemisphere. AX 3DT1: axial three-dimensional longitudinal relaxation time; MRI: magnetic resonance imaging
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case_images: FIG1
case_images: T1 hypointensity and T2 hyperintensity, without significant peritumoral edema and a largest diameter of 48mm, compressing the fourth ventricle and leading to dilation of the ventricular system (internal hydrocephalus) (Figure 1). The tumor was interpreted as a possible medulloblastoma based on the patient's profile and the clinical and neuroradiological findings.
case_images: Frozen section neuropathology of the tumor. A: cellularity suggestive of a low-grade tumor with cystic areas, original magnification 100x; higher magnification from plain A suggestive of a neuronal component (arrow), original magnification 400x; C: cytology showing abundant neuropil, tumor cell with scant cytoplasm and a cell with neuronal morphology (arrow), original magnification 400x
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case_images: FIG2
case_images: A specimen was sent for frozen section neuropathology and interpreted as a low-grade glial neoplasm (Figures 2A-2C).
case_images: Histopathology of the tumor. (A) Malformative blood vessels, myxoid areas, cords of tumor cells, some with oligodendroglioma-like morphology and floating neurons (arrow), hematoxylin and eosin stain, original magnification 200x; (B) floating neurons (arrows), hematoxylin and eosin stain, original magnification 400x; (C) solid astrocytoma-like areas of the tumor with floating neurons (arrow), hematoxylin and eosin stain, original magnification 400x
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case_images: FIG3
case_images: Areas of microcystic degeneration, myxoidisation, and malformative blood vessels were also noted throughout the specimen (Figures 3A-3C).
case_images: Immunophenotype of the tumor. (A) Glial fibrillary acidic protein underlining the glial component of the tumor, original magnification 400x; (B) S100 protein, original magnification 400x; (C) Synaptophysin, original magnification 400x; (D) high Ki-67 proliferative index; original magnification 200x
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case_images: FIG4
case_images: Immunohistochemistry revealed S100 protein expression in the oligodendroglioma-like cellular component, glial fibrillary acidic protein (GFAP) in the astrocytic components, synaptophysin positivity neuron-specific enolase and neurofilament expression in the floating neurons, Ki-67 proliferative index was high in regard to tumor cellularity (Figures 4A-4D, 5A-5C).
case_images: Immunophenotype of the tumor regarding the neuronal component. (A) Neuron specific enolase, original magnification 400x; (B, C) neurofilament, original magnifications 400x
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case_images: FIG5
case_images: Immunohistochemistry revealed S100 protein expression in the oligodendroglioma-like cellular component, glial fibrillary acidic protein (GFAP) in the astrocytic components, synaptophysin positivity neuron-specific enolase and neurofilament expression in the floating neurons, Ki-67 proliferative index was high in regard to tumor cellularity (Figures 4A-4D, 5A-5C).
case_images: (A) AX 3DT1 native and (B) AX 3DT1 postcontrast MRI of the brain showing postoperative changes in the left cerebellar hemisphere-porencephalyc cyst with peripheral gliosis and hemosiderin deposits, with peripheral contrast enhancement. AX 3DT1: axial three-dimensional longitudinal relaxation time; MRI: magnetic resonance imaging
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case_images: FIG6
case_images: Regular neuroradiology shows no recurrence of the disease and resolution of the hydrocephalus (Figures 6A, 6B).