Features of expansile right petrous apex lesion. Internal enhancement raises the possibility of intraosseous tumors. This case is known for petrous apex chondrosarcoma (pathologically proved - pathology report not available) and was referred for MRI assessment before Gamma Knife surgery.

The lesion is replacing the right Dorello's canal with the right VI nerve seen entering it. The right VI nerve is also markedly displaced to the right side and stretched by the dolicoectatic basilar artery.  Together explain the presence of diplopia.

Petrous apex chondrosarcoma is a rare lesion of the petrous apex. The presence of enhancement is a clue for suspicion of a bone tumor.