The incidence of carcinoma in encapsulated follicular thyroid lesions diagnosed by large needle biopsy.

During the period from 1975 to 1982, there were 132 patients who had encapsulated thyroid lesions diagnosed by Tru Cut needle biopsy. One hundred and nineteen patients have had operations and 20 had cancer. The 20 cancers occurred in a group of 86 lesions that were classified as microfollicular. No cancers were seen in lesions classified as macrofollicular. The incidence of cancer in the microfollicular group was 23%. This incidence of cancer was the same in Hürthle cell and non-Hürthle cell microfollicular lesions.