Anaplastic transformation of a differentiated (papillary or folicular) tyroid carcinoma is a very rare event. Ocasionally, indiffentiated and well differentiated carcinomas occur simultaneously at the same metastatic focci. All well-differentiated tyroid carcinomas could have this evolution. Some authors suggest that this transformation is induced by radioactive iodine, external radiotherapy or long term goiter. The purpose of this article is to show an anaplastic transformation in a 69 year old woman with papillary thyroid carcinoma operated by Head and Neck Surgery team at Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto - USP.
Thyroid diseases; Thyroid gland
