Warthin tumor-like variant of papillary thyroid carcinoma: a case with dedifferentiation (anaplastic changes) and aggressive biological behavior.

Warthin tumor-like variant of papillary thyroid carcinoma is uncommon and approx 80 cases have been reported in the literature. This tumor is often associated with a favorable prognosis. In this report, a Warthin tumor-like variant of the papillary thyroid carcinoma, 5-cm in maximum dimension, underwent anaplastic changes in a 74-yr-old woman. The tumor was positive for CD15 and EMA, and a high proliferative index was noted in the anaplastic area. The patient developed distant metastases after operation and died of the disease 18 mo after the operation. The present case is the first reported case of Warthin tumor-like variant of papillary thyroid carcinoma with anaplastic changes.