Ultrasonographic and cytologic findings of metastatic cancer in the thyroid gland

Background and purpose: Cancer metastasizing to the thyroid is not uncommon. Prompt diagnosis and aggressive treatment appear to contribute to better prognosis in some patients. The aim of this study was to determine the clinical manifestations, ultrasonographic and cytologic findings, and outcomes in patients with metastatic thyroid cancer. Methods: We retrospectively reviewed the medical records, including clinical courses, ultrasonographic and cytologic findings, and outcomes, of 14 patients with metastatic thyroid cancer. Results: There were various primary sites of cancer in our study population, with adenocarcinoma the most common. The sonographic images in five of 12 patients who underwent sonography showed diffusely heterogeneous hypoechoic abnormalities, while the remaining seven patients had nodular lesions. The cytologic appearances of metastatic lesions in the thyroid were characteristic of the primary malignancies. Conclusions: Most cancer metastatic to the thyroid presented as advanced metastases of primary malignancies. The sonographic appearance alone was not the ideal discriminator, and fine needle aspiration cytology helped define the diagnosis and management strategy.