Dyshormonogenetic goiters (DG) are genetically determined thyroid hype
rplasias due to enzyme defects in thyroid-hormone synthesis. We report
56 cases of DG occurring in 34 females and 22 males. The patients age
ranged from newborn to 52 yr (median 16), 75% of the cases occurring
before the age of 24. All patients presented with clinically evidence
of goiter except for two patients that were diagnosed at autopsy. Hypo
thyroidism was documented before the histological diagnosis was made i
n 36 patients (64%). The thyroid gland was enlarged and multinodular i
n all cases, weighing up to 600g. Microscopically, the most common alt
eration consisted of markedly cellular nodules exhibiting a variety of
architectural appearances, the solid and/or microfollicular patterns
predominating. Papillary proliferations and an insular growth pattern
were also present. Fibrosis was a common finding; in some instances it
was very conspicuous, resulting in irregularities at the edge of the
nodules simulating capsular invasion. Other constant features included
marked nuclear atypia and minimal amount of colloid. In 18% of the ca
ses, the degree of hyperplasia and atypia were such as to result in a
mistaken diagnosis of follicular, papillary, medullary, or undifferent
iated carcinoma. Three of the glands contained incidental small neopla
sms fulfilling the criteria of papillary microcarcinoma; one of them w
as multicentric.The presence in a thyroid gland of the combination of
these morphologic features should suggest the diagnosis of dyshormonog
enetic goiter. The only other condition we are aware of that can resul
t in a similar microscopic picture is iatrogenic goiter resulting from
the administration of antithyroidal agents.