Pulmonary carcinosarcomas (PCS) are uncommon and aggressive malignant tumors with epithelial and mesenchymal components and have a worse prognosis than other non-small-cell lung cancers. Metastases of non-thyroidal malignancies to the thyroid are rare. We reported a unique case of isolated thyroidal metastasis of PCS and discussed
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F-fluorodeoxyglucose (
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F-FDG) positivity in incidentally found thyroid nodules on
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F-FDG positron emission tomography scan.