Radiological features of metastases to the thyroid

BackgroundThyroid metastases (TM) are uncommon. Dependent on study design, the reported frequency of TM is in the range of 0.1–6% in different analyses. While clinical and histopathological features of TM were well described in the literature, radiological publications consist predominantly of isolated case reports or small series.PurposeTo estimate the prevalence, clinical signs, and radiological appearances of TM.Material and MethodsFrom 1997 to 2013, a total of 8849 patients with various disorders of the thyroid gland were treated in our institution. In 33 patients TM were diagnosed. Ultrasound (US) images were available in all patients, computed tomography (CT) of the neck in 16 patients, and magnetic resonance imaging (MRI) in nine patients.ResultsClinically, most patients (85%) presented with a painless neck mass. Primary tumors were renal cell carcinoma (79%), colorectal cancer (12%), lung cancer (3%), rhabdomyosarcoma (3%), and breast carcinoma (3%). On US, most lesions were irregular in shape wit...