Anaplastic thyroid carcinoma (ATC) is an uncommon highly malignant tumor. Osteoclastic type giant cell tumor of the thyroid is an extremely rare morphological variant of the undifferentiated carcinoma thyroid gland characterized by the presence of a large numbers of non-neoplastic multinucleated giant cells resembling osteoclasts, containing many small round to oval, uniform benign appearing nuclei. Frequent association with preexisting thyroid lesion is seen. We report here this unusual aggressive tumor in a 70 year old female who presented with dysphagia, dyspnea and a progressively increasing swelling over the anterior aspect of the neck. Histologically, many multinucleated osteoclast-like giant cells were seen accompanying the pleomorphic tumor cells and a diagnosis of anaplastic thyroid carcinoma with osteoclast like giant cells was made.
Key words: Anaplastic thyroid carcinoma, Osteoclasts, Thyroid gland, Giant cells