Fine needle biopsy diagnosis of thyroid nodules. Perspective

Abstract

Needle biopsy is the most cost-effective and reliable method for selecting thyroid nodules for observation or excision. Fine needle biopsy (FNB) is the preferred method because of safety and simplicity. FNB samples should be taken circumferentially at the periphery of the nodule to avoid the common central degeneration. The following criteria for adequate sampling reduce the potential for false negative diagnoses: e.g. a minimum of 6 aspirates, and at least 6 clusters of benign cells on each of at least 2 of the aspirates, and no malignant cells. A small rate of false positive errors is unavoidable if cancers are not to be overlooked. Study of published didactic and illustrative material permits trained and motivated cytopathologists to develop skills in FNB diagnosis quickly. FNB data may be accurate enough to supplant frozen section data for surgical planning. Patients with FNB diagnoses of benign should be followed, usually with thyroxine therapy. Nodules that do not regress after treatment for one year should be biopsied again, and observation may be safely continued if consistently benign findings are obtained. More reliable FNB diagnoses on cellular and Hurthle cell adenomas would be desirable, but it is unlikely that this will be possible in the near future.