Does Radioiodine Treatment Change the Methylene Diphosphonate Uptake in a Toxic Thyroid Nodule on Bone Scintigraphy?

A 46-year-old woman underwent a whole-body bone scan with Tc-99m methylene diphosphonate for evaluation of breast cancer metastasis. This study revealed intense focal uptake in the left lower neck and without any pathologic uptake compatible with metastasis. Additional history, physical examination, thyroid scintigraphy, and thyroid ultrasonography revealed hyperthyroidism due to a large toxic nodule consisting of multiple macro and micro calcifications in the left lobe of the thyroid. She received 30 mCi of I-131. Two years later, while the patient was in a euthyroid status, she underwent a whole-body bone scan because of bone pain. This study also revealed intense focal uptake in the left lower neck without any other pathologic uptake.