Endoscopic transsphenoidal resection of large sellar chondrosarcoma compressing the optic nerve: illustrative case.

backgroundChondrosarcoma (CS) represents a class of malignant cartilaginous tumors that are among the most common primary bone tumors in adults. While CS commonly affects the axial skeleton, intracranial presentations are exceptionally rare. Sellar region involvement is seldom documented and can result in initial misdiagnosis. OBSERVATIONS: A 54-year-old female presented with 1 week of progressive headaches and vision loss, including complete left eye vision loss and relative afferent pupillary defect. MRI demonstrated a large mass anterior to the pituitary gland, inferior to the bilateral internal carotid arteries and optic nerves, with posterior erosion of the clivus. Hyperintense T2 and hypointense T1 signals suggested a chordoma or chondroid lesion. A 2D intraoperative video illustrates the dissection around the neurovasculature as well as systematic tumor debulking. The patient recovered well with persistent left vision loss. Postoperative imaging demonstrated gross-total resection, and final pathological analysis confirmed CS. The patient received adjuvant proton-beam radiation therapy without recurrence on surveillance imaging. LESSONS: This case highlights the importance of considering CS as a differential in the investigation of sellar masses. The endoscopic transsphenoidal approach can achieve safe gross-total resection. Appropriate surgical management, combined with adjuvant radiation therapy, can result in excellent outcomes. https://thejns.org/doi/10.3171/CASE25747.