A case of metastatic thyroid cancer of the right mandible which had metastasizedto the ribs, thoracic vertebrae, lumbar vertebrae, sacrum, ilium and lung is presented. The first pathological diagnosis was clear cell carcinoma, metastatic to the mandible. The patient was given chemotherapy and radiation therapy. In spite of therapy, the metastatic tumor did not disappear between 1981 and 1990.
Of great importance was that pathologically the metastatic tumor changed from a low malignancy to high malignancy anaplastic carcinoma. Moreover, samples of the mandible and ilium which were collected at autopsy showed positive reactions to anti-human thyroglobulin antibody in immunohistological staining.
