case_images: PMC8526269_01
case_images: Neck and chest CT. The sagittal image revealed a mediastinal mass (41 x 29 mm) with clear demarcation form the right lobe of the thyroid gland. The coronal image shows the mediastinal mass interposing between the trachea and supra-aortic vessels.
case_images: CRIE2021-6584616.001.jpg
case_images: PMC8526269_01_CRIE2021-6584616.001.jpg
case_images: fig1
case_images: Imaging by computed tomography (CT) documented a large mediastinal mass (41 x 29 mm) inferior to the right lobe of the thyroid gland, interposing between the trachea and supra-aortic vessels, with probable tracheal and mediastinal vessel infiltration (Figure 1). The mass was initially considered a mediastinal lymph node due to its clear demarcation from the adjacent thyroid gland (Figure 1).
case_images: 99mPertechnetate scintigraphy showing increased diffuse uptake in the thyroid parenchyma and the absence of uptake in the mediastinal mass.
case_images: CRIE2021-6584616.002.jpg
case_images: PMC8526269_01_CRIE2021-6584616.002.jpg
case_images: fig2
case_images: Blood tests identified overt hyperthyroidism due to Graves' disease: TSH <0.02 muUI/mL (NR: 0.30-4.20), free thyroxine (FT4) 3.86 ng/dL (NR: 0.90-1.70), free triiodothyronine (FT3) 9.2  pg/mL (NR: 2.0-4.4), and thyroid-stimulating antibodies (TRABS) 21.9 UI/L (NR: <1.8). 99mPertechnetate scintigraphy showed increased diffuse uptake in the thyroid parenchyma but the absence of uptake in the paratracheal mass and in the lung nodules (Figure 2).
case_images: FDG-PET revealed multiple lesions with intense FDG uptake due to malignant disease (thyroid, mediastinal lymph nodes, lungs, bone, muscle, heart, liver, and adrenal).
case_images: CRIE2021-6584616.003.jpg
case_images: PMC8526269_01_CRIE2021-6584616.003.jpg
case_images: fig3
case_images: Restaging fluorodeoxyglucose- (FDG-) positron emission tomography (PET) showed intense uptake in the right lobe of the thyroid gland, lymph nodes, lungs, pleura, bone, muscle, myocardium, liver, kidney, and adrenal gland (Figure 3).