Extending the Graves' Triad: Thyroid Eye Disease, Dermopathy, and Acropachy: A Clinical Response to Teprotumumab.

Thyroid acropachy is a rare extrathyroidal manifestation of Graves' disease. Due to a limited understanding of the pathophysiology, no specific treatment exists. Here we discuss such a case and its response to treatment. A 25-year-old male with Graves' disease, for which he had total thyroidectomy 2 years previously, presented with worsening double vision. He also reported swelling in legs, as well as pain and stiffness in his hands and feet. Physical examination revealed bilateral asymmetric proptosis and plaque-like lesions with nonpitting edema on the pretibial skin. Fusiform swelling of the fingers and clubbing of the fingernails and toenails were also noted. Laboratory findings showed elevated thyrotropin-receptor antibodies of 81.1 IU/L (0.0-1.75). He was euthyroid with levothyroxine supplementation. Bilateral hand X-rays noted soft tissue swelling and bilateral periostitis and subperiosteal bone formation. Teprotumumab was initiated for Graves' ophthalmopathy, which improved his proptosis and orbital inflammation. Notably, the patient's pretibial myxedema, along with swelling in the bilateral metacarpals and phalanges, also improved. This case is the first to demonstrate clinical improvement in thyroid acropachy following teprotumumab. This observation suggests that pathophysiology of thyroid acropachy may involve interplay between the TSH receptor and IGF-1 receptor signaling, similar to the ophthalmopathy.