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Fig. 4 | Insights into Imaging

Fig. 4

From: Posterior fossa extra-axial variations of medulloblastoma: a pictorial review as a primer for radiologists

Fig. 4

A A 7-year-old child was sent to our hospital with a suspected brain tumor. Unenhanced brain CT scan with the axial (a) and sagittal (b) reformats. There is a well-defined hyperdense complex mass in the posterior fossa (asterisks). The mass is centered on the right CPA and surrounded by a fissure of the CSF (cleft sign), proving its extra-axial origin (arrowheads). It induces a mass effect on the ipsilateral cerebellar hemisphere, middle cerebellar peduncle, and pons (benched arrows), resulting in obstructive hydrocephalus. CPA cerebellopontine angle, CSF cerebrospinal fluid, CT computed tomography. B Brain MRI images without (a, c-d) and with intravenous contrast (b). There is a sizeable multilobulated mass located at the right CPA (asterisks). The T1-weighted (not shown) and coronal T2-weighted images (a) show iso-signal intensity relative to the gray matter. Following contrast administration, an avid enhancement was depicted (b; sagittal T1 fat saturated), with restricted diffusion on diffusion-weighted images (c, d). This mass exerts a significant mass effect on the brain stem (arrow; b) with the resultant obstructive hydrocephalus (benched arrow; a). The entire neuro-axial imaging was not remarkable (not shown). MRI magnetic resonance imaging, CPA cerebellopontine angle. C Histopathological analysis following surgery with various magnifying powers. (a) A highly cellular tumor was showing undifferentiated cells with variable growth patterns, including small uniform round carrot-shaped cells with hyperchromatic and cytoplasmic nuclei. (b) Distinct fibrillary background composed of cellular processes corresponding to the embryonic class of medulloblastoma

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