Authors: Weronika Jakubowska ¹, Stephan Tobalem¹, Léa Bernard², Francis Toupin³, Evan Kalin-Hajdu¹.  ¹Department of Ophthalmology, CUO Maisonneuve-Rosemont Hospital, Université de Montréal, Montreal, QC, Canada.,  ²Department of Hematology-Oncology, Maisonneuve-Rosemont Hospital, Université de Montréal, Montreal, QC, Canada, ³Department of Internal Medicine, Maisonneuve-Rosemont Hospital, Université de Montréal, Montreal, QC, Canada.

Author Disclosures: W. Jakubowska:  None.  S. Tobalem:  None.  L. Bernard:  None.  F. Toupin:  None.  E. Kalin-Hajdu:  None.

Abstract Body: 

Purpose:  We present the case of a 42-year-old male with bilateral diffuse paraneoplastic orbital myositis induced by a stage IA left testicular pure seminoma. This is the fifth reported case of seminoma-associated orbitopathy, and the second to occur while cancer was in the occult phase.  

Study Design:  Brief case presentation and literature review of seminoma-associated orbitopathy.  

Methods:  Description of clinical presentation, investigations and outcomes. Literature review of reports of seminoma-associated orbitopathy.  

Results:  A 42-year-old male was referred for severe thyroid-associated orbitopathy (TAO), which was deteriorating despite high doses of methylprednisolone IV. He had clinical and radiological signs emblematic of TAO, as well as laboratory testing consistent with Hashimoto’s thyroiditis. Upon presentation, he had a maximum clinical activity score (CAS) of 7/7. Each dose of methylprednisolone generated a cycle of rapid improvement, followed by swift deterioration back to baseline within 72 hours. The refractory and atypical nature of his TAO prompted the administration of Tocilizumab as well as a full autoimmune, neoplastic and infectious workup. From a therapeutic standpoint, plasma exchange was initiated while searching for an occult malignancy to aid with orbital decongestion. The discovery of an occult testicular seminoma on day 13 led to the diagnosis of paraneoplastic orbital myositis. Although less than a dozen cases of paraneoplastic orbital myositis have been reported, four of these cases have been caused by seminoma. In all four reports, patients had findings typical of TAO and in two cases, seminoma-associated orbitopathy rapidly improved once the malignancy was eradicated. Despite no evidence of metastatic disease, myositis did not immediately resolve following orchiectomy. Instead, plasma exchange was required for one month prior to achieving a CAS of 1/10. The patient has since been stable and in an inactive state.  

Conclusions:  Although seminoma-associated orbitopathy is exceedingly rare, it can masquerade as TAO and should be considered in the differential diagnosis of any young male with atypical TAO findings. Some patients with seminoma-associated orbitopathy may have a protracted disease course, even after complete eradication of the underlining malignancy.