Inferior oblique schwannoma: diagnosis and management.

Introduction: Orbital schwannoma accounts for less than 5% of orbital tumours and few cases arising in the superior orbit are reported in the literature. Purpose: To present, to our knowledge, the first report of inferior oblique-associated orbital schwannoma. Methods: Interventional case report with clinical photographs, MRI imaging, intra-operative photographs and histology. Results: A 68 year-old man presented with decreased right vision and double vision in downgaze. Examination revealed a right 3 mm ptosis, hypertropia and limitation of depression. Exploration and excision, via anterior orbitotomy, and histological examination confirmed a schwannoma located within the right inferior oblique muscle. Vision normalised post-operatively and there has been no clinical or radiological recurrence of the lesion at 2 years. Conclusions: This rare case highlights that schwannoma may occur in association with the inferior oblique complex and we suggest that schwannomas should now be considered in the differenti...