title: Anaplastic carcinoma of the thyroid with osteoclast-like giant cells.
abstract: An unusual malignant thyroid neoplasm with a morphologic resemblance to giant cell tumor of the bone is reported in a patient who presented with a rapidly growing thyroid mass and a history of pre-existing goiter. The light and electron microscopic studies disclosed areas of differentiated follicular carcinoma with gradual transition to undifferentiated carcinoma. Pleomorphic spindle-shaped cells and giant cells were accompanied by numerous osteoclast-like multinucleated giant cells. Desmosomes and interdigitating cell surfaces were apparent in the differentiated as well as undifferentiated areas on electron microscopy. These findings support an epithelial rather than a mesenchymal origin for this neoplasm.
mesh_terms: D000368:Aged; D002277:Carcinoma / Q000473:pathology* / Q000648:ultrastructure; D005260:Female; D005870:Giant Cell Tumors / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D010010:Osteoclasts / Q000473:pathology; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000648:ultrastructure