Cytologic determinants of well-differentiated thyroid cancer

Objective Fine-needle aspiration biopsy (FNAB) is the preferred diagnostic study for evaluating thyroid nodules. Despite its accuracy, many patients undergo thyroidectomy for benign nodules. This study was undertaken to identify risk factors that might increase the specificity of FNAB. methods Medical records of 422 patients who underwent thyroid surgery between 1986 and 1996 were reviewed. All patients had FNAB prior to surgery. results Of the 422 patients, 36% had benign cytology, 46% had indeterminate cytology, and 13% had cancer. In the indeterminate group, 29% of patients had cancer at surgery. Of patients with papillary cytology, 84% had malignancies. Five percent of FNABs were nondiagnostic. Neither age, gender, nor tumor size was associated with increased specificity of FNAB. conclusion There is no subpopulation of patients with indeterminate FNAB cytology at increased risk of having well-differentiated thyroid cancer