Anaplastic, sarcomatoid carcinoma of the thyroid originating from a Hürthle cell tumor.

The case of a 43-year old female with neck tumor is presented. Sections of the tumor revealed a poorly differentiated malignant neoplasm. A panel of immunohistochemical reactions was performed, and diagnosis of malignancy, most likely of a non-epithelial origin was given. Clinically, the tumor was characterized by a very high growth rate. An attempt at chemotherapy was made, but the patient died two months after the onset of the disease. At autopsy the tumor was extensively sampled. The histology revealed an anaplastic, sarcomatoid component, as well as a Hürthle cell carcinoma. The presented case is an excellent illustration of diagnostic difficulties that may be encountered in differential diagnosis of anaplastic, sarcomatoid thyroid carcinomas and true sarcomas.