The investigated tumors included 6 SP-EP with strong nuclear HOXB13 expression, 6 SP-EP with weak nuclear HOXB13 expression, 4 SP-EP without nuclear HOXB13 expression, 6 SP-MPE with strong nuclear HOXB13 expression (mostly cases containing areas with classic ependymoma features in addition to typical myxopapillary parts), 3 SP-SE with weak or absent nuclear expression of HOXB13, and 4 spinal metastases of posterior fossa ependymoma. Here, HOXB13 is linked to posterior fossa ependymoma.