Cytopathology of Hürthle cell lesions of the thyroid gland by fine needle aspiration.

The increasing use of fine needle aspiration biopsy of the thyroid has refocused attention on Hürthle cell lesions. From 2,317 cytologic studies on "cold" nodules, 70 diagnoses of Hürthle cell tumor were made. Of 49 thought to be cytologically benign, 37 were confirmed histologically; 3 others were carcinoma, 5 were autoimmune thyroiditis, and 4 were nodular goiter. Of eight considered to be cytologically malignant, histology confirmed six carcinomas and two benign tumors. Identification of nonneoplastic Hürthle cell lesions required experience. Differentiation of benign and malignant Hürthle cell tumors with a high degree of accuracy is probably not possible cytologically with the present state of our knowledge.