Extrathyroidal Radioiodine Accumulation in a Fibroadenoma of the Breast.

ABSTRACT

A 45-year-old woman with a differentiated thyroid carcinoma received adjuvant radioiodine therapy following total thyroidectomy and left modified radical neck dissection. A posttherapy planar radioiodine scan showed multifocal uptake in the thyroid bed and left chest. SPECT/CT revealed a fibroadenoma in the left breast. Six months later, an I scan showed no iodine avidity in the breast fibroadenoma, whereas ultrasonography showed no significant change in the size of the fibroadenoma. Altered radioiodine uptake of a breast fibroadenoma can be observed on follow-up scans after cytotoxic radioiodide treatment in patients with differentiated thyroid carcinoma.