Abnormal pelvic uptake on post-therapeutic radioiodine (¹³¹I) whole-body scan

Excerpt

A 36-year-old woman was referred after total thyroidectomy with central neck dissection to the Institut Gustave Roussy for radioactive iodine (¹³¹I) ablation after recombinant human thyrotropin (rhTSH) stimulation for a pT2 N0 minimally invasive follicular thyroid carcinoma. The whole-body scan (WBS) performed 3 days after the administration of radioiodine (3.7 GBq) showed thyroid bed uptake due to normal thyroid remnant and an uptake focus in the left pelvic region (a, arrow). Stimulated thyroglobulin (TG) was 10 ng/ml in the absence of TG antibodies. The pelvic ¹³¹I uptake was correlated to an ovarian cystic mass of 37 mm, as shown on ultrasonography (US) (b). The cyst was removed and histology showed a mature teratoma with a normal thyroid tissue component (c, arrow). …