Incidental Thyroid Uptake on 18F-FES PET/CT Revealing Papillary Thyroid Carcinoma.

Akkus Gunduz, Pinar; Cidemal, Mahsun; Gokcay Canpolat, Asena; Soydal, Cigdem · Clin Nucl Med · 2026

case_report · Level V

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Abstract

A 70-year-old woman with endometrial carcinoma underwent 18F-FDG and 18F-FES PET/CT for pretreatment evaluation. Both studies demonstrated focal uptake in a nodule at the inferior pole of the left thyroid lobe. Ultrasonography revealed a TI-RADS 3 nodule, and fine-needle aspiration cytology showed atypia of undetermined significance. Total thyroidectomy was performed, and histopathology revealed a 20-mm noninvasive encapsulated classic papillary thyroid carcinoma. Estrogen receptor (ER) immunohistochemistry was unavailable; therefore, the relationship between 18F-FES uptake and ER expression could not be assessed. The patient subsequently received 100 mCi of radioactive iodine.