131I Whole-Body Scan Incidental Uptake Due to Spermatocele

A 46-year-old man with papillary thyroid cancer post total thyroidectomy was referred for post radioiodine (I) whole-body scan. Whole-body images revealed intense I uptake in the bed thyroid and a focal abnormal uptake in the testicular area. Subsequent SPECT/CT demonstrated that the focal uptake corresponded to the left epididymis, and the pathology report revealed a spermatocele with no immunohistochemical features for thyroid tissue. Many cases of unexpected radioiodine uptake have been reported, and spermatocele could be counted for another possibility of incidental I uptake despite an unclear mechanism.