Endoscopy skull-base resection for ethmoid adenocarcinoma and olfactory neuroblastoma

Statement of problem: Olfactory neuroblastoma (ON) and ethmoid adenocarcinoma (AC) are rare sinonasal malignancies that often involve the skull base. Standard surgical treatment is craniofacial resection (CFR), which allows for efficient removal but entails significant morbidity and mortality. Because expanded endoscopy nasal approaches are newly developed, we aimed to describe the procedure in patients with ON and AC and compare it with CFR in terms of efficiency and morbidity. Methods: This work reports on a retrospective series of 16 patients with AC and ON treated endoscopically with anterior skull-base resection in a single institution over 9 years. Invasion of the frontal sinus, massive extension to the cerebral parenchyma, spread of the tumour above the orbits or lysis of anterior facial skeleton were contraindications for endoscopy resection. Results: Of the 16 patients, 11 had AC and 5 ON. In total, 37.5% (6) exhibited skull-base invasion. All patients had postoperative radiotherapy. In the early postoperative period, one patient experienced delayed seizure due to a minor subdural hematoma. Two delayed complications were observed: one encephalocele related to inappropriate postoperative care, which required revision surgery, and one extended radionecrosis. Five-year disease-free survival was 83% and 5-year recurrence-free survival 58%. Local control rate was 91% for AC and 100% for ON. Conclusions: With low perioperative morbidity and efficient local control, ethmoidectomy combined with anterior skull-base resection is a promising approach for managing selected cases of AC and ON. These findings need further investigation with prolonged follow-up.