Early Massive Fibrosis of a Single Extraocular Muscle Causing Severe Unilateral Euthyroid Graves' Ophthalmopathy in a Patient with Hypercholesterolemia Who Smokes.

Background: Graves' ophthalmopathy (GO) is an autoimmune manifestation of orbit affecting approximately 25% of patients with Graves' disease (GD). Autoreactive T cells involved in thyroid autoimmunity can recognize the thyroid-stimulating receptor (TSHr) expressed in orbital tissues of GO patients. Clinical manifestations of GO are rather different depending on the presence of some risk factors, such as smoking, hyperthyroidism duration, age, biological activity of anti-TSHr antibodies (TSH-R-Ab) and metabolic diseases. Case Presentation: Here, we present a rare case of euthyroid single muscular GO in a 50-year-old patient who was a smoker and had dyslipidemia for several years. The patient experienced a very rapid and severe depression of ocular motility of the right eye that caused uncorrectable and constant diplopia, severely affecting his quality of life. He was euthyroid, and TSH-R-Ab plasmatic levels were only slightly elevated. Intravenous corticosteroid pulse therapy was partially effective, and two rounds of wall orbital surgical decompression were necessary. Massive mono-muscular fibrosis was evidenced by biopsy of the right inferior rectus muscle. Conclusion: Severe unilateral, mono-muscular GO in a euthyroid Graves' patient was found to be sustained by rapid and massive fibrosis of the inferior rectus muscle of the right orbit. Clarification of the pathogenetic mechanisms of these GO clinical forms requires further studies.