Thyroid dermopathy and thyroid eye disease associated with hypofunctional autoimmune thyroid disease with high TSI/anti-TSHR antibodies improved with teprotumumab.

Thyroid dermopathy (TD) and thyroid eye disease (TED) are rare clinical entities in patients with hypofunctional autoimmune thyroid disease; however, these can be present in patients with thyroid-stimulating immunoglobulin (TSI)/anti-thyroid-stimulating hormone receptor (TSHR) antibodies. TED is believed to be associated with antibodies stimulating TSHRs and cross-talk with IGF-1 receptor (IGF-1R) pathway, prompting tissue proliferation. Teprotumumab (monoclonal antibody targeting IGF-1R) has been proven to improve symptoms of TED. It is proposed that TD share the same pathophysiology as TED. We present a case of a patient with hypofunctional autoimmune thyroid disease with high TSI/anti-TSHR antibodies who experienced significant improvement of symptoms of both TED and TD after six doses of teprotumumab. We postulate that further studies regarding the efficacy of teprotumumab in patients with TD are needed.