<prompt> In 7 year old posterior fossa mass with cyst formation, hypodense on CT, hyper intense on T2WI and showing post gadolinium nodule enhancement isMedulloblastomaEpendymomaAstrocytomaCysticercous  <response>: C i.e. Astrocytoma Posterior Fossa tumors in children Features Astrocytoma Ependymoma Medulloblastoma Cyst Formation Very cominonQ Common Rare CT scan IlypodenseQ Rare Isodense No Hyperdense Yes 15-40 CSF seeding Transforaminal spread No Yes No Calcification -10 40-50 10-15 T2WI Hyper intense HyperIso Iso T1 WI IsoHypo IsoHypo IsoHypo Postgadolinium contrast Nodule enhanceQ Mild Moderate 