Anaplastic carcinoma of the thyroid (ACT) is a rare subtype of thyroid neoplasm. This tumor represents approximately 5-10% of all thyroid malignancies and has poor prognosis ACT often arises on a long-standing thyroid nodule and has been documented to be associated with a variety of more well-differentiated thyroid carcinomas. We experienced a case of anaplastic thyroid carcinoma who had had about a year history of thyroid getter. The patient had been injected with sclerosing agents in treatment of preexisting golfer. The ACT in this case had varied cytologic and histologic appearances: pleomorphic, giant cell, spindle and squamoid. Immunohistochemically, strong cytoplasmic positivity for cytokeratin was seen in all kinds of tumor cells. Ultrastructurally, the evidences of epithelial differentiation were seen such as intercellular junctions and tonofibrils.