Benign Hürthle cell tumors of the thyroid: A diagnosis to be trusted?

The ability to differentiate benign from malignant Hürthle cell thyroid neoplasms has provoked considerable controversy. This has significant therapeutic implications, since some have advocated total thyroidectomy for all of these lesions. The principal objectives of this study were: (a) to determine whether the histologic diagnosis of Hürthle cell adenoma could be reliably made, (b) to quantitate the risk of inappropriately labelling a Hürthle cell cancer as an adenoma, and (c) to ascertain whether the type of operative procedure affected the clinical course. We reviewed 272 patients who had undergone thyroid resection for benign Hürthle cell neoplasms at the Mayo Clinic from 1960 to 1980. All pathologic sections were rereviewed. Postoperative follow-up was available on 233 patients (86%), with a mean of 8.9 years. A minimum of 5 years of follow-up was obtained on 10% of the patients. Nodules ranged in size from 0.3 to 11 cm; 195 (55%) were 2 cm or larger. Surgical resection was limited to one side in 137 (50%) patients and involved both sides in 135 patients. No total thyroidectomies were performed. Evidence of malignancy-a local recurrence-developed in only 1 patient, and she died of unrelated causes. None of the 272 patients died of thyroid cancer, and none showed evidence of metastases. Our data is in agreement with most published reports, with only 6 (0.9%) of 642 reported patients being diagnosed incorrectly. These tumors can be accurately separated into benign and malignant. Routine total thyroidectomy for Hürthle cell adenomas is not justified.