Unusual 131 I Uptake in Talus May Reveal Distant Papillary Thyroid Cancer Metastasis With Anaplastic Transformation

Talus metastasis is rarely observed on a 131 I whole-body scan (WBS). We report a case of abnormal 131 I uptake in the talus on the post-therapeutic WBS in a 54-year-old woman with papillary thyroid cancer (PTC). The patient received 2 courses of radioactive 131 I therapy (RAIT) after the thyroid surgery. WBS after the second dose of RAIT showed that 131 I uptake in the right talus declined than the last post-therapeutic WBS presented. The talus lesion was confirmed to be metastatic PTC with anaplastic transformation by pathologic examination and immunohistochemistry.