Incidental Gallbladder Cancer Visualized From Posttreatment 131I Whole-Body Scan

A 72-year-old woman with papillary thyroid cancer post-total thyroidectomy was referred for post-I treatment whole-body scan. Images revealed focal uptake within the gallbladder. Cholecystectomy was subsequently performed, and the pathology report showed well-differentiated adenocarcinoma. Given a history of papillary thyroid cancer, the iodine uptake was reasonably explained as metastasis; however, gallbladder metastasis was extremely infrequent. Literature described the incidental radioiodine retention in the gallbladder as false-positive findings, which can be normal variants or benign hepatobiliary conditions. Primary gallbladder malignancy could be counted for another possibility despite controversial mechanism of uptake.