[Undifferentiated carcinoma of the thyroid gland with osteoclast-like giant cells--a case report].

A case of undifferentiated carcinoma of the thyroid gland with osteoclast-like giant cells resembling those of a giant cell tumor of the bone is presented. A 79-year-old female had noticed swelling on the left frontal neck. Histological examination of frontal-neck tumor revealed undifferentiated carcinoma of the thyroid gland. The patient was treated with a Cobalt 60 unit and received a total tumor dose of 2800 rad. However, because of a rapid increase in size of the tumor and its metastasis, the patient died about 2 months after admission. An autopsy was performed. Histologically, the tumor differed from the usual undifferentiated carcinoma of the giant cell type in having osteoclast-like giant cells with many small, uniform, benign appearing nuclei. It is proposed that the osteoclast-like giant cell is reactive rather than neoplastic in nature because of the benign appearance, phagocytotic activity and some ultrastructural features.