Is Primary Optic Nerve Sheath Schwannoma a misnomer Report of Two Cases and Literature Review

Purpose: To report clinic-pathological characteristics of two cases with optic nerve sheath schwannoma and review the previous 11 cases in the literature (Totally 13 cases in the literature till now). Methods: There were 2 men of 52 and 22-year-old who presented with gradually progressive visual loss in 2006 and 2012, respectively. The first patient did not have proptosis but the second one presented with huge proptosis. Their best corrected visual acuity at the time of orbitotomy was light perception with 4+ relative afferent pupillary defects. Their clinical course and repeated imaging will be demonstrated. Results: Both patients underwent orbitotomy procedure in 2007 and 2013 and ONSS was the final pathological diagnosis. Both finally end up with total visual loss and no recurrence of tumor in 12 and 5 years follow up. Literature review and re-visit of pathological and clinical presentations of previous cases are summarized to find out if such a diagnosis is correct or misnomer. Conclusion: Optic nerve sheath schwannoma seems to be a misnomer in at least 11 out of 13 reported cases