Cutaneous metastasis from papillary carcinoma of the thyroid. A case confirmed by monoclonal antithyroglobulin antibody.

A 59-year-old woman with a history of papillary carcinoma of the thyroid gland developed three reddish nodules on the scalp. A skin biopsy showed a dermal tumor composed of sheets of clearly differentiated thyroid vesicles. Cutaneous metastases of thyroid carcinoma are very rare and this case is the first case confirmed by immunoperoxidase studies using monoclonal antithyroglobulin antibody. Positive reactions were obtained in colloid and at apices of thyrocytes. Monoclonal antibodies to human thyroglobulin may offer a unique opportunity to confirm the tissue origin of cutaneous metastasis.