The patient, a 30-year-old female, presented to the clinic with a 2-month history of nasal congestion and nose bleeding. Local hospital examination revealed a large tumor in the left maxillary sinus, invasion of the intraorbital, pterygoid fossa, infratemporal fossa, base of the middle cranial fossa, and parapharyngeal space. Local biopsy was adenoid cystic carcinoma. This is a malignant tumor of glandular origin, characterized by easy invasion along nerve fibers and therefore earlier intracranial invasion. Due to the patient’s own poor vision in the healthy side of the eye (right), the family’s desire to preserve the diseased side of the eye (left) was extremely strong. Therefore, an endoscopic assisted medial canthotomy was used to perform resection of the tumor in the intraorbital, maxillary sinus, and skull base regions. Postoperatively, the patient was biopsied at the middle segment of the infraorbital nerve as well as at the proximal foramen (the second cranial expenditure of the trigeminal nerve), and no tumor invasion was observed. Postoperatively, the patient recovered well with normal vision in the affected eye. Adjuvant proton heavy ion therapy was performed. He is currently being followed up. Figure 1 below shows the preoperative images. After surgery, complete resection of the tumor was seen in the infratemporal fossa at the base of the skull and in the parapharyngeal space, with a local low signal shadow from a local absorbable dressing.