A case of pretibial myxedema treated with teprotumumab

Abstract

I&D: incision and drainage IGF-1: insulin-like growth factor 1 IGF-1R: insulin-like growth factor 1 receptor PTM: Pretibial myxedema TSH: thyroid-stimulating hormone INTRODUCTION Pretibial myxedema (PTM) is a dermatological manifestation of autoimmune thyroiditis, most commonly Graves’ disease, due to intradermal deposition of mucin. PTM has a prevalence of 1% to 5% in patients with Graves’ disease, and it is more prevalent (25%) in those with exophthalmos. Orbital fibroblasts and the pretibial dermis share antigenic sites that underlie the autoimmune pathophysiology that causes Graves’ disease. While no cure exists for the orbitopathy or pretibial myxedema associated with Graves’ disease, several effective treatments have been studied, such as topical and intralesional corticosteroids, combined pentoxifylline and intralesional triamcinolone, rituximab, plasmapheresis, and intravenous immunoglobulin. Additionally, intralesional octreotide, which has insulin-like growth factor 1 (IGF-1) antagonist properties, has demonstrated a beneficial effect on PTM, likely suppressing hyaluronic acid secretion by fibroblasts through IGF-1 inhibition. These therapies have been shown to at least partially alleviate Graves’ ophthalmopathy and/or PTM. However, current definitive treatments are lacking and can cause dose-limiting adverse reactions. Recently, teprotumumab, a human monoclonal antibody inhibitor of insulin-like growth factor 1 receptor (IGF-1R), has been shown to reduce proptosis in patients with thyroid-associated ophthalmopathy. One case has been reported in which a patient underwent treatment of Graves’ associated ophthalmopathy with teprotumumab and had coincidental improvement in her PTM. However, there is little data on its long-term efficacy, and it is not