Intraosseous Cellular Schwannoma in the Infraorbital Region: A Rare Case.

BACKGROUND Schwannomas are benign tumors of Schwann cell origin, and their intraosseous presentation in the infraorbital region is exceptionally rare. We report a case in which computed tomography (CT) revealed an expansile lesion in this location, subsequently diagnosed as a cellular schwannoma. This report underscores the importance of histological analysis in the differential diagnosis of infraorbital lesions, particularly to distinguish schwannoma from entities such as neurofibroma. CASE REPORT Our patient was a 31-year-old man with right infraorbital facial pain, described as an "electric shock" sensation, radiating to the maxillary region, with gradual clinical progression over 2 years. It was also observed that his right eyeball became protruded and displaced upward, leading to vertical diplopia. Clinical and neurological examination revealed facial asymmetry, mild upward divergent strabismus, right exophthalmos, and allodynia during tactile stimulation of the right maxillary region. Craniofacial CT and magnetic resonance imaging (MRI) revealed a circumscribed 2.5×3 cm mass occupying the floor of the orbital cavity and invading the maxillary sinus. Histopathological analysis showed organized neoplastic cells and strong expression of the S-100 protein, as well as immunostaining for the Ki-67 protein, indicating proliferative activity. The final diagnosis was cellular schwannoma. CONCLUSIONS This case highlights the importance of differential diagnosis in rare lesions of the infraorbital region and the need for histological analysis to avoid misdiagnosis and surgically preserve functional nerves.