Primary Ewing's sarcoma of the petroclival bone: A case report and literature review.

Primary Ewing's sarcoma (ES) is typically seen within the long bones, vertebrae, or pelvis. Uncommonly, it can be found within the cranium among the rarest locations for primary ES are the skull base, in particular, the petroclival bone.The patient is a 68-year-old female with past medical history of Stage III breast cancer who presented with severe retro-orbital headache and diplopia due to a cranial nerve VI palsy. Magnetic resonance imaging (MRI) revealed a mass at the left petroclival bone with extension into the adjacent left petrous apex and into the posterior aspect of the left cavernous sinus proximal to the carotid artery. The patient subsequently underwent an endoscopic transsphenoidal biopsy. Pathological and molecular analysis supported a diagnosis of ES. The patient then underwent neoadjuvant chemotherapy and radiotherapy. At 12 month-follow-up, her petroclival ES demonstrated significant interval decrease in size on MRI surveillance imaging.This is the third case of primary ES of the petroclival bone to be reported in the literature. In this patient, management consisted of surgical incisional biopsy followed by adjuvant radiation and chemotherapy. Knowledge and awareness of this type of tumor is important for the skull base surgeon.