Cardiac Metastasis from Poorly Differentiated Thyroid Carcinoma: A Rare Case Report and Review of the Literature

Figures

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  Figure 1. Neck vein and cardiac colour Doppler ultrasound on 20 February 2025. (A) Right internal jugular vein: heterogeneous hypoechoic intraluminal material with partial flow, suggestive of venous tumor thrombus. (B) Superior vena cava: extensive heterogeneous hypoechoic filling defects with reduced flow, consistent with venous tumor thrombus. (C) Transthoracic echocardiography (apical four-chamber view): 3.9 × 4.4 cm mildly echogenic right atrial mass with limited mobility and turbulent flow, consistent with intracardiac tumor thrombus. (D) Two-dimensional transthoracic echocardiography: right atrial mass with heterogeneous echotexture and multiple hypoechoic areas, extending toward the tricuspid orifice.

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  Figure 2. Transthoracic echocardiography on 19 March 2025. (A) Apical four-chamber view showing an enlarged right atrial mass with heterogeneous echotexture and multiple hypoechoic areas, indicating tumor thrombus progression. (B) Two-dimensional measurement view demonstrating the enlarged right atrial mass measuring 5.3 × 4.0 cm, with limited mobility and extension toward the tricuspid valve orifice.

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  Figure 3. PET/CT on 12 March 2025, showing intraluminal tumor thrombus with intracardiac extension. (A) Axial PET image showing focal increased 18F-FDG uptake in the superior mediastinum corresponding to the right atrial mass and venous tumor thrombus. (B) Axial CT image demonstrating low-attenuation filling defects in the superior vena cava and right brachiocephalic vein, consistent with extensive venous tumor thrombus. (C) Axial fused PET/CT image showing intense FDG avidity within the right atrial mass and continuous venous tumor thrombus, confirming metabolically active neoplastic involvement. (D) Whole-body maximum intensity projection (MIP) image demonstrating the extent of disease with abnormal FDG uptake in the neck and superior mediastinum, corresponding to the venous tumor thrombus and intracardiac extension.