Thyroid adenomas may occur singly or as portions of benign nodular goiters. Their cause is unknown. This capacity is, with rare exception, seen only in benign lesions. Thus, a so-called hot nodule, an area of thyroid tissue that is the sole active focus in the gland, can be safely watched without surgery. Radionuclide scanning establishes the diagnosis by showing a concentration of the isotope in an area that corresponds to the palpable nodule.
Nodular goiter remains one of the great enigmas of thyroid disease.
A common disorder, beginning usually in persons in their 30s, nodular goiter affects women much more often than men. The pathogenesis is obscure, and the variegated pathological findings may show patches of atrophy, fibrosis, hyperplasia, calcification, and involution. The disease may reflect a defect in intrathyroidal regulation of thyroid function by iodine, but just how this defect would lead to the particular pathological findings is not clear. The clinical attributes of the disease are important. It is probably among these patients that the hyperthyroidism that occurs in association with some nodular goiters develops.