Metastatic tumours to the thyroid gland: report of 3 cases and brief review of the literature

BACKGROUND: Metastases to the thyroid are encountered rarely in clinical practice, but the number of cases seems to have increased in recent years. The reason of this increase may be a more frequent use of fine-needle aspiration biopsy (FNAB) and the use of more sophisticated, complicated imaging techniques in patients with thyroid masses. Also, in addition to these reasons, the use of more organo-specific immunohistochemical antibodies in the examination of surgical specimens may affect the differential diagnosis of malignant tumours. CASE REPORTS: Three metastatic tumours to thyroid were found in the retrospective review of malignant thyroid tumours diagnosed between January 1993 and December 2007. The primary tumours were clear cell carcinoma of the kidney, squamous cell carcinoma of the lung and breast carcinoma-ductal type. CONCLUSIONS: A detailed clinical history, careful histological examination and essential immunohistochemistry helped in attaining the correct diagnosis.