Orbital schwannoma with hyposmia as the only presentation: Case report and a literature review on differential diagnosis.

Orbital schwannoma is a rare benign tumor, originating from the Schwann cells of the orbital peripheral nerve sheath. Orbital schwannoma is easily misdiagnosed if the patient shows atypical presentations and atypical appearance on MRI imaging. A 56-year-old male experienced hyposmia for 1 year and was misdiagnosed with cavernous hemangioma pre-operation. This case was treated by surgery through the endoscopic trans-nasal approach. After operation, the patient had no recurrence or complications. Preoperative diagnosis for these cases remains difficult. Combined imaging modalities including computed tomography (CT) and magnetic resonance imaging (MRI) can help in differential diagnosis. Surgery is the main treatment modality for treating orbital schwannoma. Outcomes in most cases are favorable without complications or recurrence.