Fine needle aspiration cytology of metastatic tumors to the thyroid: a 20-years single institution retrospective study

Abstract

Abstract Introduction/Objective Metastases to the thyroid are rare and represent approximately 2% to 3% of all thyroid malignancies. In this study we aim to report our institution experience with these tumors over the last twenty years. Methods/Case Report Our laboratory information system was searched for metastatic tumors to the thyroid diagnosed on fine needle aspiration cytology from 2003 to 2023. The pathology reports as well as clinical data for these cases were then reviewed retrospectively. Results (if a Case Study enter NA) A total of 35 cases were found over the period of twenty years. The ages ranged from 30 to 83 with a mean of 60 years. 19 patients were female (54%) while 16 were males (46%). Clear cell renal cell carcinoma was the most common source of metastasis (12 cases), followed by squamous cell carcinoma of the head and neck (6 cases), followed by lung or breast adenocarcinoma, and neuroendocrine tumors (3 each). There were four metastatic sarcomas to the thyroid: osteosarcoma, synovial sarcoma, angiosarcoma and leiomyosarcoma. There was two metastatic adenocarcinoma (unknown primary), one melanoma case as well as one case of colon cancer. Conclusion Although rare, metastasis to the thyroid gland do happen and could be a potential diagnostic pitfall in a limited cytology specimen.