The Thyroid and its Diseases Chapter 18,Thyroid Nodules

Thyroid cancer accounts for only 0.4% of all cancer deaths, with an incidence of 11 cases and about 0.5-0.6 deaths per 100,000 population in the United States each year,according to the November 2011 SEER report (http://seer.cancer.gov/statfacts/html/thyro.html). Its clinical importance, by contrast, is out of all proportion to its incidence, because cancers of the thyroid must be differentiated from the much more frequent benign adenomas and multinodular goiters. The latter, depending on the criteria employed, occur in up to 4% of the population, and thyroid nodules may be present in 20% or more of adults subjected to routine thyroid echography. The differential diagnosis of thyroid nodules is now easily accomplished by fine needle aspiration cytology in 60-90% of the cases, allowing a significant reduction in the number of thyroid surgeries performed for thyroid nodules. This chapter is concerned with the clinical and pathological description of benign and malignant thyroid nodules and with the diagnostic and therapeutic approach to them. What will be said applies also to nodules found within a multinodular goiter, although as a separate entity this disease is discussed in Chapter 17.