P-61 EYE SEE YOU: GRAVES' OPHTHALMOPATHY: FIRST OCCURRENCE 10 YEARS POST-THYROIDECTOMY
Authors: Plesca Simina , Martiniuc Diana , Robu Larisa , Matei Anca , Preda Cristina 
Published: January 2025

Abstract

Introduction
Graves' ophthalmopathy is most commonly associated with Graves' disease and less frequently with Hashimoto's thyroiditis. Graves’ ophthalmopathy is also known as thyroid-associated ophthalmopathy or thyroid eye disease, because it sometimes occurs in patients with euthyroid or hypothyroid chronic autoimmune thyroiditis. While de novo Graves’ ophthalmopathy has been seen after definitive treatment with radioactive iodine, it is uncommon after total thyroidectomy.

Clinical Case
We report the case of a 74-year-old female, non-smoker, with a history of nodular goiter who underwent total thyroidectomy. Ten years post-surgery, the patient reported unilateral exophthalmos in the left eye accompanied by retro-orbital pain. Neck ultrasound showed no residual thyroid tissue, additionally, the levels for thyroid-stimulating hormone receptor antibodies (TRAb), thyroid peroxidase antibodies (TPOAb), and antithyroglobulin antibodies (TGAb) were negative. Consequently, ophthalmologic and neurological evaluation as well as orbital magnetic resonance imaging (MRI) were recommended. Initially, the histopathological result of nodular goiter and the negative TRAB levels ruled out Graves' disease. However, the orbital MRI did not reveal any other causes or local lesions, raising the suspicion of Graves' ophthalmopathy despite negative TRAB levels. Given the patient's active ophthalmopathy (clinical activity score 4), treatment with methylprednisolone was initiated, with symptomatic improvement by the end of therapy. Two years later, an elevated TRAB level was detected for the first time, and neck ultrasound revealed residual tissue in the left thyroid bed. We attributed this to the antibodies stimulation on a possible minimal residual thyroid tissue, which was undetectable on periodic ultrasound for a over 10 years, but which subsequently became hyperplastic. Therefore, corroborating the anamnestic, clinical and paraclinical data, the diagnosis of Graves' ophtalmopathy with positive TRAB has been confirmed. The most recent follow-up revealed an improved but still active nature of the ophthalmopathy (clinical activity score 3), hence, treatment with methylprednisolone and mycophenolate sodium was reinitiated. The patient is being closely monitored to establish the best ongoing therapeutic approach.

Conclusion
The development of Graves' ophthalmopathy after total thyroidectomy for nodular goiter is a rare occurrence with several proposed mechanisms. These include the release of thyroid autoantigens post-surgery triggering an autoimmune response, potential alterations in antigen-presenting cell function influencing immune reactions, and the impact of postoperative infections on immune modulation. While the exact pathways remain speculative, understanding these mechanisms could enhance our approach to monitoring and managing autoimmune complications in thyroid surgery patients.Figure 1:Orbital MRIThe orbital MRI shows that the posterior pole of the right eyeball is approximately 3 mm anterior to the interzygomatic line and the posterior pole of the left eyeball is at the level of the interzygomatic line. The distance between the interzygomatic line and the anterior pole of the eyeball is approximately 25 mm on the right side and 23 mm on the left side. Bilateral extraocular muscles with increased thickness, homogeneous enhancement, more intense on the right side.