Osteoclastoma-like anaplastic carcinoma of the thyroid

Anaplastic carcinoma is a highly malignant tumor that is partially or totally undifferentiated. The use of fine needle aspiration cytology (FNAC) to diagnose anaplastic carcinoma with osteoclast-like giant cells, has been rarely reported. We report here a case of osteoclastoma - anaplastic carcinoma - that was diagnosed on cytology in a 58 year-old female patient, who presented with a progressively increasing swelling over the anterior aspect of the neck. Multinucleated giant cells resembling osteoclasts are rarely seen in the giant cell variant of anaplastic carcinoma.