Radioiodine uptake in an ovarian mature teratoma detected with SPECT/CT.

A 28-year-old woman underwent a near-total thyroidectomy for papillary carcinoma. Before radioiodine therapy, the serum thyroid-stimulating hormone level was 50 μIU/mL, the thyroglobulin level was 1 μg/L, and the antithyroglobulin was negative. She received 100 mCi of I for ablation of residual thyroid tissue. After therapy, I whole-body scan demonstrated focal uptake in the right pelvic area, which localized to the right ovary on SPECT/CT fusion images. The ovarian cyst was resected, and histopathological examination revealed a mature teratoma without thyroid tissue component. At 6-month follow-up, the whole-body radioiodine scan was normal, and serum thyroglobulin was undetectable.