Excellent Response to Multimodal Therapy Approach in Hyperfunctioning Metastatic Follicular Thyroid Carcinoma Diagnosed on 123 I-SPECT/Ultrasound Fusion Imaging.

An 83-year-old woman presented with new-onset hyperthyroidism and suspicious thyroid nodules on ultrasound (US). Conventional 99m TcO 4 thyroid scintigraphy showed hyperfunctioning areas that could not be clearly assigned to the US findings. With the aid of 123 I-SPECT/US fusion imaging, suspicious nodules were unambiguously identified as autonomously hyperfunctioning lesions. Additional 123 I whole-body scan revealed iodine-avid lymphonodular and pulmonal metastases. Clinical diagnosis of hormone-active thyroid carcinoma was made and histologically confirmed. Because of significant hyperthyroidism as well as multiple partially iodine-negative metastases, a multimodal treatment regime consisting of 131 I radioiodine therapy, surgery, and radiation therapy was conducted, leading to almost complete remission.