Tumors of the thyroid gland are classified on the basis of being benign or malignant, the presence or absence of associated thy-rotoxicosis, and the diffuse or irregular quality of the glandular enlargement. If the enlargement is sufficient to cause a visible swelling in the neck, the tumor is referred to as a goiter.
All grades of goiter are encountered, from those that are barely visible to those producing disfigurement. Some are symmetric and diffuse; others are nodular. Some are accompanied by hyper-thyroidism, in which case they are described as toxic; others are associated with a euthyroid state and are called nontoxic goiters.