Cellular tumor formed of sheets of closely packed rounded, oval or some spindle cells with enlarged hyperchromatic nuclei and scanty cytoplasm. Nuclei display coarse chromatin pattern. Anaplasia and mitoses are marked. Tumor shows prominent perivascular arrangement. Marker study (synaptophysin, chromogranin, GFAP, OLIG2, EMA, INI-1, P53, CK, LCA, CD20, Ki-67) is recommended for definitive typing.
Right posterior fossa mass lesion: Well defined intra-axial cortical based right cerebellar mass lesion measuring about 6x4x5 cm, no surrounding edema, causing compression of cerebellar vermis and 4th ventricle, as well as compress pons and medulla oblongata and causing tonsillar herniation 13 mm below foramen magnum causing narrowing of cervico-medullary junction, compression of upper cervical spinal cord, the lesion show internal cystic changes, restricted in DWI, low heterogeneous enhancement post contrast study.
Soft tissue fragments collectively measured 3.5x3x0.8 cm and were totally embedded.
Rt. Posterior fossa mass lesion, biopsy: