A schwannoma is a benign tumor that arises from the Schwann cells surrounding the axons of the peripheral nerves. Nasal and sinonasal schwannomas are extremely rare and account for only 1% of all schwannomas. Schwannomas are essentially treated by surgical removal of the tumor, including the base. We managed a patient with a schwannoma that originated from a paranasal sinus and extended to the skull base. The patient, a woman in her 70s, presented with discomfort in her right eye due to a right ethmoid sinus tumor. The intranasal findings showed a smooth-surfaced, hard mass in the right ethmoid sinus that compressed the mucosa of the middle nasal passage. CT and MRI showed that the tumor had eroded the skull base and medial wall of the orbit, thinning the bone, extending to the frontal sinus, and deviating the nasal septum; however, no apparent bony destruction was noted. A biopsy was performed under local anesthesia, and the histopathological diagnosis was suspected schwannoma. The operation was performed via an endoscopic approach. As a preliminary step prior to tumor removal, the left ethmoid sinus was opened widely, a right medial maxillectomy was performed, and the nasal septum was separated caudal to the tumor. After completion of the segmental resection, the tumor and dura were carefully dissected, and the base of the tumor was removed. Because the dura was partially damaged, the spinal fluid leak was closed using free fat (bath plug closure method) and a vascularized nasoseptal flap. The histopathological findings comfirmed the mass as a schwannoma.
