514 JOURNAL OF OPHTHALMIC AND VISION RESEARCH 2014; Vol. 9, No. 4 INTRODUCTION Schwannomas are encapsulated tumors which grow from peripheral nerves and rarely occur in the orbital and periorbital regions. Orbital schwannoma accounts for 1–4% of all orbital tumors, [1,2] are usually benign, but malignant changes have been described in some cases. [3] They usually arise from sensory rather than motor nerves. About 24% of orbital schwannomas have been reported to origin from the first division of the trigeminal nerve; however, in the majority of orbital schwannomas, the origin may not be identified based on radiological and clinical findings. Preoperative and postoperative neurological deficits usually lead to the identification of the source of these tumors. [4] Schwannomas originating from the oculomotor nerve are extremely rare. Approximately, 45 cases of oculomotor Orbital Oculomotor Nerve Schwannoma Extending to the Cavernous Sinus: A Rare Cause of Proptosis Hina Kauser 1 , MBBS, MS; Omar Rashid 1 , MBBS, MS; Waseem Anwar 1 , MBBS, MS; Sabina Khan 2 , MBBS, MD 1 Department of Ophthalmology, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India 2 Department of Pathology, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi, India Abstract Purpose: To report a case of orbital oculomotor nerve schwannoma extending to the cavernous sinus through the superior orbital fissure presenting with proptosis, but without any neurological sign. Case Report: A 32‑year‑old man presented with axial proptosis of his left eye. Visual acuity and other ocular examinations were normal. Orbital magnetic resonance imaging revealed a well‑defined fusiform retrobulbar lesion in the left orbit extending into the superior orbital fissure and left cavernous sinus measuring 43 mm × 21 mm × 19 mm and causing superomedial displacement of the optic nerve and axial proptosis. The patient was scheduled for surgery, and gross total excision was done. Postoperatively, the patient developed total third nerve palsy. Pre and postoperative third nerve deficit confirmed the origin of the tumor from the oculomotor nerve. Histopathological examination revealed schwannoma. Conclusion: Orbital oculomotor nerve schwannoma, although rare, can be the cause of proptosis. Diagnosis can be confirmed histopathologically. It is a benign tumor; however, it can extend intracranially without any neurological symptoms. Therefore, neuroimaging is essential to rule out intracranial extension. Early surgical removal is mandatory. Keywords: Cavernous Sinus; Oculomotor Nerve; Proptosis; Schwannoma Case Report Correspondence to: Hina Kauser, MBBS, MS. RZ‑904/24, Gali 24, Flat 202, Tughlakabad Extension, New Delhi ‑ 110 019, India. E‑mail: hina3kauser@yahoo.co.in Received: 01‑05‑2013 Accepted: 30‑08‑2013 nerve schwannomas have been reported in the literature so far. In a recent review, only 4 cases of oculomotor nerve schwannomas located in the orbit have been described. [5] Herein, we report a case of orbital oculomotor nerve schwannoma extending to the cavernous sinus through the superior orbital fissure presenting with proptosis. As per our knowledge, no case of orbital schwannoma with these characteristics has been reported in the literature. CASE REPORT A 32‑year‑old man presented with axial proptosis of the left eye [Figure 1a and b]. He had noted painless protrusion of this eye since 6 months before which was J Ophthalmic Vis Res 2014; 9 (4): 514‑516. Access this article online Quick Response Code: Website: www.jovr.org DOI: 10.4103/2008‑322X.150833