Also called nodular hyperplasia
Nontoxic: no hyperthyroidism present
Physiology: low T3 / T4 (various mechanisms) means negative feedback loop is inactive, causes increased TSH, which causes follicular hypertrophy and hyperplasia (goiter) with minimal colloid, later follicular atrophy with massive storage of colloid
Simple goiter: also called diffuse nontoxic goiter or colloid goiter
Thyroid gland usually 40g or more
Eventually converts into multinodular goiter
Multinodular goiter: irregular enlargement of thyroid gland due to repeated episodes of hyperplasia and involution (degeneration) of simple goiter
Thyroid gland often 100g or more, may resemble a neoplasm, particularly if a single firm dominant nodule is present
Nodules are clonal or polyclonal, and are due to heterogeneous responses of follicular epithelium to TSH
Exophthalmos of Graves disease is not present
Colloid goiter: descriptive but not a diagnostic term; means massive storage of colloid within follicles often with flattened epithelium