Diffuse and Nodular Goiter

The term goiter refers to an enlarged thyroid gland, in the absence of autoimmune thyroid diseases and thyroid cancer. The traditional classification of goiter typically includes the endemic, sporadic and familiar forms. As a matter of fact, these three types are non-distinguishable from the clinical and pathological point of view because they only differ for the various influence on their development of endogenous and exogenous factors. Goiter in the absence of thyroid nodules (diffuse goiter) is common, but is usually asymptomatic. In the clinical practice nodular goiter is more frequently encountered, being more common in areas with iodine deficiency, where it involves more frequently elderly people, and represents an evolution of the diffuse goiter, that is more typical of the youth. The nodular goiter may present with multiple distinct or coalescent nodules. Thyroid nodules may be also single or dominant in the context of a goiter, or isolate in a gland of normal size, have different pathogenesis and pathology. They may be hyperfunctioning and then cause of hyperthyroidism, or non-functioning and causing pressure symptoms only when large enough. Although non-functioning nodules are rarely symptomatic, they require a diagnostic work-up to exclude the presence of a thyroid cancer. Thyroid cancer is the most frequent endocrine cancer, but is rarely cause of death. Nonetheless, for the high prevalence of thyroid nodules, usually asymptomatic and discovered incidentally in the course of imaging techniques such as ultrasound (US) and computerized tomography (CT), the diagnostic procedures applied in thyroid nodular disease have increased rapidly in the last years leading to publication of several consensus statements and guidelines related to the best possible cost-benefit and valid approach to the diagnostic evaluation of thyroid nodules. The prevalence of diffuse and nodular goiter is very much dependent on the population iodine nutrition. The prevalence of thyroid nodules is also influenced by the iodine dietary intake, but also depends on the method employed for its identification. Epidemiological studies based on thyroid palpation in iodine-sufficient areas have demonstrated a prevalence of 10% in women and 2% in men. In systematic studies thyroid nodules, mostly non-palpable, can be identified by thyroid US in 20-50% of subjects (1). The prevalence of thyroid nodules is higher in women and after 60 years of age.