A posterior fossa ependymoma that arises in the posterior fossa with characteristic DNA methylation patterns including retention of nuclear H3 p.K28me3 (K27me3) expression, absence of CpG island hypermethylation, absence of global DNA hypomethylation, and absence of EZHIP overexpression. The disease is posterior fossa group B ependymoma (Monarch Disease Ontology term MONDO_0956993).