Which of the following statements regarding fine needle aspiration cytology of a thyroid nodule are true?

a. It differentiates neoplastic and nonneoplastic nodules in most cases

c. It cannot differentiate malignant and benign follicular or Hürthle cell neoplasms

d. It is not recommended when a patient has a history of head and neck radiation

When interpreted by a skilled cytologist, fine needle aspiration is highly accurate and is considered the preferred method of selecting patients with thyroid nodules for surgery. Nearly 80% of patients with thyroid nodules were spared surgical exploration as a result of such studies in one report. Because of the risk of false-negative diagnoses (10%), advocates of this technique emphasize the importance of clinical judgment in addition to the cytologic study in selecting operative candidates. In most cases, fine needle aspiration cytology enables the pathologist to distinguish nonneoplastic from neoplastic nodules and to identify the type of malignant tumor. Papillary, medullary, and anaplastic carcinoma all have a typical cytologic appearance. Cytologic studies cannot differentiate malignant from benign follicular or Hürthle cell neoplasms. In this case, a definitive diagnosis depends on histologic examination of the entire excised tumor

Fine needle aspiration has dramatically reduced the number of diagnostic surgical operations for benign lesions in centers where it is used extensively. In patients with thyroid nodules and a history of previous head and neck radiation, operation is generally recommended regardless of cytologic findings. In these patients, both benign and malignant lesions may develop and the chances of sampling error are considerable.