Hurthle cell tumours of the thyroid. Personal experience and review of the literature.

Hurthle cell carcinoma represents about 5% of differentiated thyroid carcinomas. The prognosis of the malignant type of the tumour is still under debate as some Authors have reported that Hurthle cell adenoma occasionally behaves like Hurthle cell carcinoma. Aim of the present study was to evaluate previously reported data and personal experience on the clinical and pathological features of patients affected by Hurthle cell tumour that may predict disease progression and death. In the literature, factors potentially associated with decreased survival were identified and include: age, disease stage, tumour size, extra-glandular invasion, lymph node disease, distant metastases, extensive surgery, radioiodine treatment. From 1992 to 2003, the Authors identified 28 patients affected by Hurthle cell tumour, 9 with Hurthle cell adenoma and 19 with Hurthle cell carcinoma. Of these, 22 were females and 6 males. Mean age of patients affected by adenoma was 49.7 years (range 30-72) vs. 49.3 years (range 15-72) in Hurthle cell carcinoma patients. In all patients, total thyroidectomy was performed. At histology, 9 adenomas, 5 "minimally invasive" and 14 invasive carcinomas were found. Post-operatively, in Hurthle cell carcinoma patients, TNM staging showed 9 patients with stage I, 5 stage II, 4 stage III and one stage IVa (UICC, 2002). All invasive carcinomas underwent (131)I therapy (91-585 mCi). One Hurthle cell carcinoma patient received external beam radiotherapy. The mean follow-up period was 62 months (range 6-324). Relapse was not observed in any of the cases with adenoma. Only one Hurthle cell carcinoma patient showed distant lung metastases at 60 months' follow-up. In conclusion, Hurthle cell carcinoma was not found to present a more aggressive behaviour than follicular carcinoma, when risk factors, including extent of tumour invasion, were taken into account. None of the patients with Hurthle cell adenoma showed a relapse or death caused by the tumour.