Endoscopic Endonasal Removal of a Large Petrous-Apex Epidermoid Tumor With Clival Involvement and Intradural Invasion

Introduction: epidermoid tumors comprise 1% of intracranial tumors. although reported, intraosseous epidermoid tumors are even more rare. cystic lesions of the petrous apex are uncommon and surgically challenging; the most rare pathology is presumed to be epidermoid. case presentation: this is a case of a 61-year-old woman with a large skull-base tumor extending inferiorly from the c1-c2 articulation and superiorly to the tuberculum sella. the lesion replaced the left-sided petrous apex, and the lateral extension of the tumor reached the styloid process. the tumor displayed intradural invasion medial to the internal auditory meatus, producing an intra-axial mass at the level of the upper pons. the patient presented with a 4-month history of headache and total unilateral deafness. under image guidance, an endoscopic endonasal approach was used to totally resect the tumor. by following the tumor’s dural defect, the intra-axial part of the tumor was safely resected, and the dural defect was successfully repaired. conclusions: image-guided endoscopic endonasal surgery is a versatile approach that can safely and easily address a large epidermoid tumor in this challenging region, obviating the need for demanding and sophisticated transcranial surgery.