Iodine-avid Adenomyoepithelioma of the Breast

An 83-year-old woman with follicular thyroid cancer (FTC) presented with elevated thyroglobulin levels 5 years after second ablative radioiodine therapy (RAI). A subsequent 18F-FDG PET/CT revealed small pulmonary nodules and a lesion of the right breast with pathologically increased FDG-uptake. Unexpectedly, the lesion also showed radioiodine uptake under a performed third RAI and was visually absent after a fourth course of treatment. Histologically after core and excisional biopsy, a benign adenomyoepithelioma was confirmed. This is, to our knowledge, the first reported iodine avide adenomyoepithelioma and highlights a rare diagnostic pitfall.