The case of an 83-year-old female with a history of a two months enlarging goiter is presented. Clinically, a firm goiter with fixation to surrounding soft tissues was found. Fine needle aspiration cytology was performed with the conclusion of a sarcomatoid variant of anaplastic carcinoma of the thyroid gland; biopsy was recommended. The patient was operated on and died six months after operation with metastatic dissemination in lymphatic nodes and lungs. Histologically, an invasive high-grade tumor composed of irregular, sometimes bizarre spindled or polygonal cells intermingled with foci of chondroid tissue was seen. The cartilage comprised lobularly arranged chondrocytes with irregular nuclei; bi- or multinucleated chondrocytes were present as well. The diagnosis of thyroid anaplastic carcinoma with chondrosarcomatous component was established. Differential diagnostics of this tumour is discussed.

        Key words: thyroid gland – anaplastic carcinoma – chondrosarcoma