Hurthle cell neoplasms of the thyroid gland revisited.

Hurthle cell tumours (benign and malignant) have been regarded as lesions with uncertain biological behaviour. However recent clinico-pathological studies have shown that they should be categorized as benign or malignant on the basis of capsular and/or vascular invasion, like other differentiated thyroid neoplasms. The fact that the tumours are composed of Hurthle cells is irrelevant. Currently, histological parameters do not seem to predict biological behaviour of Hurthle cell carcinomas.