An unusual case of pelvic radioiodine uptake in a 30 year old woman after thyroidectomy for papillary thyroid carcinoma was studied. Radioiodine and bone scanning localized the uptake to pelvic soft tissue and at surgery a teratoma was found in the wall of the rectum. The radioiodine was confined to this tumor and was localized to gastric mucosal epithelium.
