Schwannoma Originating from Infraorbital Nerve

ABSTRACT

Schwannomas are well-differentiated solitary benign tumors that originate from the schwann cells of the nerve sheath. They can readily occur in the head and neck regions, but the schwannoma originating from the infraorbital nerve is extremely rare and usually painless, slow-growing, and without specific symptoms. The author experienced a rare case of infraorbital schwannoma, which was completely removed through the intraoral approach. A 20-year-old woman was admitted to our hospital for a painless, solid and circular mass located on the right infraorbital region. The eyeball movement and visual field were normal. There was no globe displacement or proptosis. Preoperative computed tomography demonstrated 13x10x5 mm-sized soft tissue mass. On March 2011, the mass was removed through an intraoral approach. On histopathological examination, the gross specimen consisted of a smooth, well-encapsulated and light yellowish solid mass, measuring 12x7x5 mm. Microscopically, it presented a typical manifestation of schwannoma with Antoni A area with Verocay body, and Antoni B area on H&E stain. The result of the immunohistochemical staining was positive for the S-100 protein. The patient had hypoesthesia of the nasal septum and vestibule in the postoperative period, and this finding confirmed that the internal nasal branch of infraorbital nerve was the nerve in which the schwannoma originated. Infraorbital schwannomas are very rare and must be included in the differential diagnosis of the orbital masses inferior to the eyeball. In the case of early diagnosis, the small-sized infraorbital schwannomas can be completely removed without any scar through an intraoral approach.