Endoscopic ipsilateral mononostril transethmoidal removal of an orbital apex cavernous hemangioma: illustrative case.

BACKGROUND: Orbital apex cavernous hemangiomas are rare, benign vascular malformations that pose significant surgical challenges due to their proximity to critical neurovascular structures. While traditional approaches such as orbitotomy or craniotomy remain standard, they are associated with higher morbidity. Endoscopic endonasal techniques have emerged as minimally invasive alternatives, particularly for medially located lesions. OBSERVATIONS: A 60-year-old woman presented with progressive retro-orbital pressure, binocular diplopia, and a mild left abduction deficit. MRI revealed a 10 × 8-mm hyperintense, homogeneously enhancing lesion in the left posterior extraconal orbital apex. Resection was performed via an endoscopic ipsilateral mononostril transethmoidal approach using intraoperative neuronavigation. A well-encapsulated, reddish-purple mass was delivered en bloc without complications. Intraoperative MRI confirmed gross-total resection. Postoperatively, the patient experienced immediate symptom relief, with resolution of diplopia within 1 week and no new cranial nerve deficits. She was discharged on postoperative day 1. LESSONS: This case demonstrates that the ipsilateral mononostril transethmoidal approach is a safe and effective option for select orbital apex cavernous hemangiomas. It provides direct access to the medial orbital apex with minimal morbidity and rapid recovery. Successful outcomes depend on multidisciplinary collaboration, careful planning, and appropriate patient selection. https://thejns.org/doi/abs/10.3171/CASE251038.