Asymmetric diffuse thyroid uptake on F-FDG 18 PET/CT in patient with subacute thyroiditis: Case report and literature review

A 48-year-old man with an intermittent fever of 39.0 & DEG;C for more than three weeks underwent computed to-mography (CT) and blood testing, which revealed no clues. Antibiotics were administered, but his condi-tion did not improve. Fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomo-graphy ( F-FDG PET/CT) showed right-lobe-dominant diffuse thyroid uptake. On technetium-99m ( Tc)-18 99m pertechnetate scintigraphy, the thyroid gland could not be visualized, and he was diagnosed with subacute thyroiditis (SAT). When asymmetric F-FDG diffuse thyroid uptake on PET/CT is observed in a patient with a 18 fever of unknown origin (FUO), SAT may need to be considered.