Figure 2.

Hypothetical model of the pathogenesis of nodular goiter: Nodular goiters are very heterogeneous in their functional, structural, and molecular genetic features (4). It is currently thought that, in persons with both a genetic predisposition and an iodine deficiency, a “mutagenic environment” arises (increased cellular proliferation and formation of free radicals) that promotes the appearance of somatic mutations in thyrocytes. A clonal thyroid tumor forms when the genetic defect is not repaired and the mutation is of a type that gives the proliferating cells a selective advantage