PMC5718304_01
An ill-defined hypodense lesion (arrows) with mild peripheral patchy enhancement is involving the cerebellar hemisphere. The lesion is reaching up to the roof of fourth ventricle resulting in its near complete obliteration with moderate to severe dilatation of third and fourth ventricles.
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The lesion measured 4.5 x 4 cm2 and was causing near complete obliteration of the fourth ventricle with moderate to severe dilatation of lateral and third ventricles (Figure 1).
Histological patterns of primitive cell population: (a) hypercellualr areas showing primitive cells arranged in sheets, (b) trabecular arrangement, (c) trabeculae, pseudopapillae and neural tube-like structures and (d) perivascular pseudorosettes.
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Some of these rosettes had empty central lumina, while others demonstrated a central core of fibrillary material (Figures 2 and 3).
Neuropil-rich areas: (a) abrupt transition of hypercellualr areas with neuropil-rich areas, (b) multilayered rosettes lined by primitive cells, central area contains neurofibrillary material, (c) few primitive cells and few gangliocytic cells (arrows) against fibrillary background and (d) neurofilament IHC stain in neuropil-rich background.
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Some of these rosettes had empty central lumina, while others demonstrated a central core of fibrillary material (Figures 2 and 3).