PAPILLARY AND FOLLICULAR THYROID-CARCINOMA METASTATIC TO THE SKIN - ACASE-REPORT AND REVIEW OF THE LITERATURE

Cutaneous metastases from thyroid cancers are rare. We report th case of an otherwise asymptomatic 81-year-old woman with an enlarging scalp lesion. Her solitary skin metatasis was the presenting feature of thy roid carcinoma. Routine histopathology of the lesion was notable for a n atypical clear cell neoplasm. Immunohistochemistry was positive for thyroglobulin. Subsequent resection of the thyroid gland identified se parate foci (< 1 cm) for both papillary and follicular carcinoma. Alth ough such immunohistochemical staining has been used previously, it ha s never been reported to provide the definitive diagnosis for a solita ry cutaneous metastasis from the thyroid. Previous tumors had anatomic features in a clinical Context that permitted identification by routi ne light microscopy. Clear cell features found in the follicular focus of carcinoma in the thyroid suggest that it is the primary. A worldwi de literature review reveals that follicular carcinoma has a greater p reponderance than papillary carcinoma for cutaneous metastasis and tha t the majority of skin metastases from either papillary or follicular thyroid cancer are localized to the head and neck.