Long-term remission of steroid-resistant Graves' orbitopathy after administration of anti-thymocyte globulin – description of the first case

Introduction: The management of patients with Graves’ orbitopathy (GO) and severe dysthyroid optic neuropathy (DON), refractory to corticosteroid therapy and radiation therapy is a major challenge. As T cells infiltrate in orbital tissues plays a central role in the pathogenesis of GO, the administration of rabbit anti-thymocyte globulin (rATG) may be considered as a potential new method of therapy. Case presentation: We present a case of the woman with 25-years history of Graves-Basedow disease, treated with subtotal strumectomy, two courses of radioiodine therapy, who developed severe DON during glucocorticoid therapy according to EUGOGO protocol for GO with a prompt application of orbital radiotherapy and ineffective re-administration of glucocorticoid methylprednisolone. The patient received an experimental therapy with rATG (two doses of 1.5 mg/kg). The clinical improvement in GO was noted at 6-week examination after rATG administration. The improvement in GO and DON, confirmed by pattern visual evoked potentials (PVEP), continued a year after administration, in parallel to the normalization of CD4/CD8 ratio of peripheral blood T lymphocytes. Conclusions: Thymoglobulin may be useful in the management of severe steroid-resistant GO with dysthyroid optic neuropathy. The effectiveness of this new therapy requires a larger number of observations.