FRI552 Orbitopathy As The Sole Manifestation Of Hashimoto’s Thyroiditis In A Euthyroid Patient: A Case Report

Disclosure: C. Labib: None. Z. Saeed: None. M. Trabulsi: None. F. Ramharrack: None. INTRODUCTION: Thyroid associated ophthalmopathy (TAO) is caused by an autoimmune process involving the orbital tissue, however, its etiopathogenesis is still largely unclear. It is common in hyperthyroid patients with Graves’ disease and has also been reported in euthyroid and hypothyroid Graves’ patients with positive thyroid receptor antibodies (TRAb). However, only 5% of patient with Hashimoto’s thyroiditis (HT) develop orbitopathy. Here we report an unusual case of a male patient, clinically and biochemically euthyroid, who had severe bilateral exophthalmos due to underlying Hashimoto’s thyroiditis. CASE PRESENTATION: A 68-year-old male patient was evaluated for worsening bilateral eye protrusion associated with redness and grittiness for many years. The patient was otherwise asymptomatic; denied fatigue, any change in weight, constipation, joint/muscle pain or any other symptoms. On physical examination he was noted to have bilateral moderate periorbital edema, conjunctival injection along with mildly enlarged thyroid. Initial labs showed normal TSH 4.10 mIU/L (0.4-5.0mIU/L) and free T4 0.8 ng/dL (0.8-1.8 ng/dL). Further labs were notable for normal antithyrotropin antibody (TRAb) 1.09 IU/l and normal TSI less than 89%. Anti-thyroid peroxidase antibody (anti-TPO) level was as high as 12 IU/mL (less than 9 IU/mL). Thyroid US showed multinodular goiter with bilateral nodules. A Subsequent FNA was benign. The degree of exophthalmos on the Hertel ophthalmometer was 30 mm bilaterally. Orbital magnetic resonance imaging (MRI) showed proptosis of the left and right globes as well as prominence of intraorbital fat. Extraocular musculature was symmetric bilaterally and only minimally prominent but diffuse. Treatment with teprotumumab infusion was started with improvement in the patient’s symptoms. CASE DISCUSSION: Usually mild eye symptoms are seen in Hashimoto’s thyroiditis such as dryness, blurred vision, upper eyelid retraction and loss of lateral third of eyebrows. In rare cases it can cause orbitopathy similar to that seen in Graves’ disease. Like Graves’ orbitopathy, in addition to reversing the underlying thyroid abnormalities, moderate-to-severe orbitopathy is treated with corticosteroids or teprotumumab. This case sheds the light on exophthalmos being an atypical presentation of Hashimoto’s thyroiditis in a clinically and biochemically euthyroid patient. Physicians should be cognizant of this rare manifestation for prompt recognition and early treatment which can prevent corneal involvement and blindness due to optic nerve compression. Presentation: Friday, June 16, 2023