Fine-needle aspiration biopsy of the thyroid.

This article describes contemporary understanding of fine-needle aspiration (FNA) biopsy of the thyroid gland, with particular reference to its triage role in the investigation of thyroid nodules. A team approach involving the pathologist and the clinician is crucial for its success. A nonsuction technique with a 25- or 27-gauge needle is recommended. Performance of FNA biopsy by physicians with faulty technique and interpretation of FNA specimens by pathologists without proper training are detrimental to patient outcome. These problems may lead to a high failure rate, which in turn might discourage use of FNA biopsy and could lead to use of other diagnostic methods that are more expensive or are associated with greater morbidity (or both). The size of the nodule may be important in determining the need for surgery in some patients. Decisions regarding surgery that are based on the size of the nodule and the specific cytologic features are discussed. A standardized terminology for reporting is proposed.