Diagnosis of thyroid metastasis in cancer patients with thyroid mass by fine needle aspiration cytology and ultrasonography

Background. Thyroid metastasis is generally thought to be infrequent. To evaluate its occurrence, fine needle aspiration cytology and ultrasound of the thyroid gland were performed in nonthyroid cancer patients with thyroid mass. Methods. A total of 20 nonthyroid cancer patients (6 males and 14 females with a mean age of 55 ± 7 years) with thyroid mass were examined with thyroid ultrasound and fine needle aspiration cytology. Their underlying malignancies included lung cancer in 10 patients, breast cancer in 7 patients, cervical cancer in 2 patients and colon cancer in 1 patient. Results. Thyroid metastases were diagnosed in 4 patients (20%), 2 with breast cancer and 2 with lung cancer. For 3 of them, thyroid ultrasound showed solitary hypoechoic nodule, and in 1 case, multiple nodular lesions were demonstrated in each lobe. In addition, neck lymph nodes were noted in 3 patients. In the remaining 16 cancer patients, thyroid ultrasound showed either multiple or solitary nodular goiter change with no neck lymph node involvement. Fine needle aspiration cytology (FNAC) yielded nonthyroid adenocarcinoma in 4 metastatic cases. The 2 breast cancer patients received finally total thyroidectomy and were still alive 1 year after operation. While in the other 2 lung cancer cases, only supportive treatment were given due to advanced stages and the patients died within months. Conclusions. Thyroid metastases could occur at a high frequency in nonthyroid cancer patients with thyroid mass from our small series. By combining FNAC with ultrasound, a clinical diagnosis of thyroid metastasis is attainable in cancer patients with thyroid mass.