Thyroid-Shaped Iodine Uptake in the Scrotum: An Unusual Finding on 131 I Whole-body Scan.

We report a thyroid-shaped iodine uptake in the scrotum incidentally detected on an 131 I whole-body scan (WBS). A 62-year-old man with papillary thyroid carcinoma underwent 131 I ablation therapy after total thyroidectomy. A postablation whole-body scan after 7 days revealed a butterfly-shaped uptake in the lower pelvic region on the anterior image, which was suspected to be an unusual form of urinary contamination. However, additional lateral images demonstrated that the tracer activity was not superficial. Computed tomography revealed a bilateral scrotal hydrocele that corresponded to the 131 I uptake in the lower pelvis on WBS. This case presents a previously unreported hydrocele incidentally detected on 131 I WBS, with iodine uptake in the bilateral scrotal regions, shaped like a thyroid gland.