The clinical presentation of dyshormonogenetic goiter depends upon the severity of the inborn error in thyroid hormone synthesis. A severe defect manifests as neonatal or congenital hypothyroidism, growth abnormalities, and mental retardation (cretinism). Milder defects may present later in life as goiter and mild hypothyroidism. Most patients present by age 25 yrs. Microscopically, the hyperplastic changes are diffusely present throughout the gland. There is hypercellularity, follicular hyperplasia, and reduced amount of colloid. The follicles are generally small, compact and tightly spaced. The follicular cells show marked cytologic atypia in the form of bizarre hyperchromatic nuclei.