Inferior Displacement of the Mandibular Canal and Mental Foramen Enlargement in an Asymptomatic Intraosseous Schwannoma of the Mandible: A Case Report

Abstract

Intraosseous schwannoma of the mandible is a rare benign nerve sheath tumor that often resembles an odontogenic lesion radiographically. As many reported cases are asymptomatic, the absence of neurosensory symptoms is not a specific diagnostic clue. We report a 33-year-old female with a mandibular lesion detected incidentally on panoramic radiography. She had no pain, swelling, or numbness, and neurosensory examination of the mental nerve distribution was normal. The involved teeth were vital and showed no mobility or percussion pain. Panoramic radiography revealed a well-defined unilocular radiolucency extending from the right mandibular premolar region to the mesial root of the first molar. Computed tomography showed a relatively homogeneous low-attenuation lesion, inferior displacement of the mandibular canal, smooth thinning and resorption of the buccal and lingual cortices, and remodeling and enlargement of the mental foramen, without root resorption. Thus, marked remodeling centered on the inferior alveolar nerve pathway was present despite preserved neurosensory and pulpal function, demonstrating radiographic-clinical dissociation. Surgical excision revealed an encapsulated yellowish-brown solid mass adherent to the inferior alveolar nerve near the mental foramen; funnel-shaped enlargement of the mental foramen was observed intraoperatively. Histopathological examination demonstrated mixed Antoni A and Antoni B areas, and the tumor cells were positive for S100 protein and neuron-specific enolase, confirming schwannoma. Mild postoperative hypoesthesia resolved within five months, and no recurrence was observed during the available two-year follow-up. The combination of mandibular canal displacement and mental foramen enlargement may suggest a neurogenic origin and aid differential diagnosis and nerve-preserving surgical planning, even in patients without neurosensory symptoms.