MON-334 Papillary Thyroid Carcinoma in a Young Patient with Graves Disease

Abstract Disclosure: M. Fathima: None. J. Gilden: Novartis Pharmaceuticals. Introduction: Thyroid cancer in patients with Graves disease (GD) has been reported with incidences varying from 2.3% to 21.1%. More than 85% of thyroid cancer cases in patients with GD were classified as papillary thyroid carcinoma (PTC). GD and PTC can be concomitant. Although researchers have long studied the connection between these entities, a definitive correlation has not yet been established. We present a rare case of a 16-year-old female with GD who because of suspicious findings, underwent further investigation and was found to have PTC. Case presentation: A 16-year-old Mexican American female with no known family history of thyroid disorders or cancer was referred to the Endocrinology clinic due to GD after receiving treatment with Methimazole for 2 months. The patient presented with complaints of difficulty swallowing and breathing. Physical examination revealed a palpable nodule in the left thyroid lobe. Laboratory investigation yielded notable results: thyroid-stimulating hormone (TSH) level <0.010 uIU/ml (normal 0.27 - 4.20 uIU/ml), free T4 level 0.97 ng/d (normal 0.60 - 1.40 ng/d), and free T3 level was 5.68 pg/mL (normal 2.52 - 4.34 pg/mL). An elevation in thyroglobulin was observed, measuring 29.7 ng/mL (normal 0.8-29.4 ng/mL). The thyroid ultrasound unveiled a solid hypoechoic nodule on the left thyroid measuring 1.8 X 1.1 X 1.5 cm with wider-than-tall margins and questionable punctate focus. The nodule was classified as TIRADS 5, indicating high suspicion. Fine needle aspiration cytology analysis was suggestive of PTC. Considering these findings, the patient underwent a total thyroidectomy. The pathological evaluation following the procedure indicated PTC in the left lobe measuring 1.4 x 1.4 x 1.2 cm and papillary microcarcinoma in the right lobe measuring 0.4 x 0.3 cm. However, there was no display of invasion or extrathyroidal extension. In the postoperative period, thyroglobulin level was <0.4, there were no clinical or biochemical features of hypoparathyroidism or laryngeal nerve injury, and levothyroxine 100 mcg was initiated. Conclusion: The incidence of PTC in GD has been increasing over time and the rate of cancer in GD is higher when compared to euthyroid controls. Although the etiology of the increased risk of PTC in GD is not completely understood, thyroid stimulating immunoglobulin (TSI) may play a role. Some studies indicate that thyroid autoimmunity and PTC can occur together. However, a definitive pathogenic correlation has yet to be established. This case sheds light on the evolving understanding of the coexistence of GD and thyroid cancer. Thyroid carcinoma associated with GD is more prevalent than previously considered. It is essential to maintain high clinical suspicion for hyperthyroid patients who may have thyroid carcinoma. This awareness can help guide appropriate investigations and plan definitive treatment. Presentation: Monday, July 14, 2025