An Atypical Presentation of Thyroid Eye Disease in a Patient With a Remote History of Graves' Disease.

Thyroid eye disease (TED) is commonly associated with Graves' disease, often occurring concurrently or shortly after its diagnosis. However, atypical presentations, such as TED emerging years after thyroid function stabilization, are rare and can pose diagnostic challenges. These delayed cases may lead to misdiagnosis or delayed treatment, underscoring the importance of maintaining clinical vigilance, even in patients with long-term thyroid stability. We describe a patient with a remote history of Graves' disease who developed TED years after achieving thyroid stability on hormone replacement therapy following radioactive iodine therapy. She presented with unilateral strabismus and diplopia, prompting further evaluation. While TED was not initially suspected, and despite thyroid function tests within normal limits, significantly elevated thyrotropin receptor antibodies (TRAb) suggested disease reactivation. Progressive orbital signs and symptoms confirmed the diagnosis of TED, and treatment led to both clinical improvement and a subsequent decline in TRAb levels, reinforcing the role of antibody monitoring in atypical cases. This case highlights the need for ongoing awareness of TED in patients with prior Graves' disease, even long after thyroid function normalization, particularly with atypical presentations lacking classic TED findings. The marked elevation of TRAb served as a key biomarker for disease reactivation, emphasizing the value of antibody monitoring in late-onset TED cases. Early recognition and appropriate management are crucial to preventing complications and improving patient outcomes.