A variant of adenomatous goiter with characteristic histology and possible hereditary thyroglobulin abnormality.

A variant type of adenomatous goiter was identified in 24 of 2160 patients with adenomatous goiter who underwent thyroidectomy. The characteristics of the thyroid gland in these 24 patients included large goiter, small follicles, scant colloid, and columnar follicular cells containing yellow-green granules on hematoxylin-eosin staining. The thyroid gland was slightly orange-red, and electron microscopic examination showed abundant lysosomes with colloid droplets. When comparing the features of this group with those of 24 patients with common adenomatous goiter, the incidence of familial predisposition to thyroid diseases in the former group was higher. The age at the time of detection of goiter was lower, i.e. 17 +/- 15 vs. 44 +/- 17 yr (P < 0.001, variant type vs. common type), the serum total T4 concentrations were lower (84 +/- 21 vs. 103 +/- 18 nmol/L; P < 0.01), and the serum TSH concentrations were higher (2.4 +/- 2.1 vs. 1.0 +/- 0.9 mU/L; P < 0.01). Thyroid radioiodine uptake was remarkably increased (49 +/- 22 vs. 16 +/- 9%; P < 0.001), and lower levels of serum thyroglobulin were noted (33 +/- 51 vs. 484 +/- 603 micrograms/L; P < 0.01). The thyroglobulin content was low in the thyroid gland studied. The data suggest that the etiology of this variant type of goiter is a hereditary abnormality in thyroglobulin synthesis, and this type of goiter may be distinguished from common adenomatous goiter by the characteristic morphology of the thyroid gland in addition to clinical findings.