Thyroid nodules and thyroid cancer--diagnostic aspects

The clinical evaluation of patients with thyroid nodules is a common problem confronting the clinician. The vast majority of such nodules are benign, but concern that such a thyroid swelling may harbour malignancy demands prompt and accurate diagnosis. Furthermore, it is clear that properly treated differentiated thyroid carcinoma is associated with an excellent prognosis. The objective of investigating patients presenting with thyroid nodules is to define the small number of malignancies with minimum inconvenience to the patient in the most cost-effective way. There are no laboratory tests which reliably differentiate benign from malignant disease. The traditional approaches of radionuclide and ultrasound scanning have been shown to be poorly specific in the diagnosis of malignancy, resulting in many unnecessary operations for benign lesions. These tests have been replaced in many centres by fine needle aspiration cytology, with surgery for abnormal cytological findings alone. This technique is easily performed in an out-patient clinic and is well tolerated; accuracy in the diagnosis of thyroid neoplasia of up to 97% can be achieved.