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Distant spread
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Approx 15% risk of spinal spread from post. fossa tumors
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Spread occurs throughout the CSF pathways
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Most often nodular
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Very uncommon at presentation
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Infratentorial tumors have higher risk of seeding than
supratentorial tumors
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More common with anaplastic ependymoma
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Incidence of leptomeningeal spread varies with:
Tumor grade (low grade 5%, high grade 10-15%)
Tumor location (5% supratentorial, 10-15% infratentorial)