PMC9037889_01
Brain macroscopic view shows the base of brain with (infratentorial) left cerebellar tumor with surrounding hemorrhage (arrow) and liquefactive necrosis (arrowhead).
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Noted at the base of the brain was a partly necrotic tumor with surrounding haemorrhage of the left cerebellar hemisphere measuring 60x60mm (Figure 1).
Photomicrographs of the tumor - A - shows biphasic tumor cellular primitive cells arranged in ependymoblastic rosettes - (white arrowheads), C - papillae and trabeculae (white arrowheads) with B - intervening hypocellular zones composed of differentiated neuropil and sheets of primitive cells (red stars); D - Areas of necrosis (white star). (A - D, H&E x 100)
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The cellular areas composed of primitive cells arranged in sheets, papillae, tubules (reminiscent of immature neural tubes), and multilayered ependymoblastic rosettes (with central lumen) (Figures 2A &2C) and intervening hypo-cellular zones with abundant neuropil containing occasional true rosettes (Figure 2B). Necrosis was seen in cellular zones (Figure 2D).
Photomicrographs of the tumor shows- A and B - diffuse membranous vimentin staining of the multilayered rosettes; C - diffuse granular synaptophysin staining of the hypocellular/neuropil zones; D - negative staining for pan-cytokeratin (A, B, C and D - 100X).
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Immunohistochemical stains showed reactivity of the multilayered rosettes for vimentin (Figures 3A &3B) while negative for pan-cytokeratin (Figure 3D). The hypo-cellular areas with abundant neuropil showed reactivity for synaptophysin (Figure 3C).
Immunohistochemical reaction for Ki67.
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Ki-67 proliferation index was high in the cellular areas (Figure 4).