False-positive whole-body scan after I-131 therapy in a patient with intestinal scar.

The I-131 whole-body scan is a useful test to investigate the presence of metastatic disease of thyroid cancer after thyroidectomy. A 53-year-old woman received I-131 4 months after total thyroidectomy for papillary thyroid carcinoma for postsurgical ablation of the residual tumor cells. Whole-body scan demonstrated focal uptake of I-131 in the right iliac fossa that persisted 2 days later even after administration of laxatives. Computed tomography of this area showed only focal bowel scar presumably resulting from a complicated appendectomy 31 years ago. Intestinal adhesions accumulate I-131 and give false-positive activity on whole-body I-131 scans.