The detection rate of thyroid incidentalomas is increasing; in fact, as many as 2.3% of patients undergoing FDG PET-CT for other indications have been found to have thyroid incidentalomas. The risk of malignancy in these thyroid incidentalomas can be as high as 47%. The increased uptake and the focal uptake pattern of F-18 fluorodeoxyglucose (FDG) in the thyroid during positron emission tomography (PET)-computed tomography (CT), and the calcification of the thyroid incidentaloma, are associated with even higher risk of malignancy. We report a case of a lady undergoing FDG PET-CT for breast cancer staging but noted to have a calcified thyroid incidentaloma, which was proven to be follicular thyroid carcinoma.