SAT537 Thyroid Cancer Mimicking Acute Coronary Syndrome

Disclosure: N.M. Rodrigues: None. B. Alexander: None. J. Palacios Merchan: None. Background: The use of thyrotropin –alpha for preparation of remnant ablation is associated with superior short-term quality of life and similar rates of remnant ablation as thyroid hormone withdrawal. Usually treatment with thyrotropin-alpha is well tolerated, but we need to be aware of the potential side effects. Clinical case: 61-year-old Hispanic female with multinodular goiter, underwent total thyroidectomy for compressive symptoms. The pathology report showed 4 cm invasive papillary carcinoma, well-differentiated follicular variant, with invasion of an adjacent parathyroid gland. The margins were negative, and no nodal involvement was noted. Due to the extra thyroidal extension, the plan was to undergo radioactive iodine ablation. She received two doses of thyrotropin-alpha. On the following day, 24 hours after the second thyrotropin-alpha, she complained of severe left sided chest pain and went to the emergency room. Initial workup for acute coronary syndrome was negative. CT angiography done to rule out aortic dissection showed diffuse multifocal bilateral pulmonary nodules and a 2.4 cm lytic lesion on the superior aspect of the manubrium suggesting osseous metastasis. She had severe tenderness to palpation of her chest - mostly of the sternum. We decided to perform a whole-body scan to determine if the lesions were iodine avid. Due to down trending TSH at 25 microIU/mL, she received another dose of thyrotropin-alpha. Her TSH subsequently increased to 209.4 microIU/mL with a thyroglobulin level of 2250 ng/mL. Whole body scan showed evidence of metastatic disease to the lungs bilaterally and bone metastatic lesions in the manubrium and left proximal femur. . The pain did not improve with morphine but responded well to oral diclofenac. One week later, she again received two doses of thyrotropin-alpha in preparation for radioactive iodine ablation with 200 mCi of I-131 due to the metastatic lesions. She started taking prednisone 50 mg daily for 1 week before the thyrotropin- alpha injection and continued prednisone 25 mg for five additional days. She remained asymptomatic during the radioactive iodine treatment. Conclusion: Thyrotropin-alfa has a manufacturer warning that it can lead to an increase in tumor burden resulting in severe pain and inflammation, especially at the metastatic sites. Even though imaging to look for metastasis is usually not part of the protocol before radioactive iodine ablation, it could be considered in patients with high-risk features on the surgical pathology report. This could prevent possible complications related to thyrotropin-alpha by identifying patients at risk. It is recommended that patients with cancer near their trachea, in their central nervous system, or in their lungs receive treatment with glucocorticoids to reduce inflammation. This pretreatment is shown to be very effective in preventing these complications. Presentation Date: Saturday, June 17, 2023