Section shows a cellular tumor with sheets of dyshesive and closely packed rounded and ovoid large cells with enlarged hyperchromatic and focally vesicular nuclei with scanty cytoplasm. Nuclei mostly display fine chromatin pattern with occasional rosettes. Anaplasia is moderate to marked and mitotic activity is observed. No evidence of tumor necrosis. Picture consistent with medulloblastoma, anaplastic/large cell variant, WHO grade IV tumor. Marker study (beta-catenin, p53, GFAP, CD56, Synaptophysin and Ki67) is needed for confirmation and further molecular classification.
Posterior Fossa solid cystic mass.
Soft tissue fragments collectively measured 1.8x1.5x0.7 cm, totally embedded.
Posterior Fossa solid cystic mass: