PMC5831236_01
(a) Brain MRI T1 before contrast. (b) Brain MRI T1 after contrast. (c) FLAIR. (d) Spine MRI T1 after contrast.
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fig1
Brain MRI before and after contrast (Figures 1(a), 1(b), and 1(c)) revealed an ill-defined lesion at the superomedial aspect of the right middle cerebellar peduncle distorting the upper aspect of 4th ventricle and the adjacent folia pattern.
(a) H&E stain illustrating the primitive cells and the peculiar angiocentric pattern of distribution. (b) Immunohistochemical stain with CD45 (LCA) showed absence of immunoreactivity excluding lymphoma. (c) Pancytokeratin immunohistochemical stain was nonimmunoreactive excluding a metastatic carcinoma. ((d) and (e)) CD56 and CD99 immunohistochemical stains showed strong membranous pattern of immunoreactivity of the tumor cells. (f) Synaptophysin showed weak immunoreactivity.
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fig2
On the contrary, there were angiocentric arrangement and peculiar perivascular accentuation (Figure 2(a)) commonly seen in CNS lymphoma and other glial tumors such as ependymomas.