Cytophotometric determination of nuclear size and DNA distribution in different hyperfunctioning thyroid lesions.

Nuclear enlargement in hyperfunctioning thyroid lesions which has been found in earlier cytophotometric studies is also one of the criteria in the subjective histological estimation of thyroid function. Histopathological assessment is, however, often unreliable. In the present study stage scanning cytophotometric measurements in Feulgen-stained tissue sections were used to determine the nuclear changes encountered in non-toxic and toxic nodular goitre, and in toxic diffuse goitre. To ensure optimal selection of specimens for measurements autoradiography was used. Specimens of toxic diffuse goitre invariably had enlarged nuclei, but no difference was found between nodules in nontoxic and toxic nodular goitre. In fact, the same nuclear area was found in hot nodules, warm nodules and perinodular tissue in non-toxic nodular goitre, and in hot nodules in toxic nodular goitre. Thus there are lesions with clear-cut clinical, biochemical, and autoradiographic hyperfunction that do not have enlarged nuclei. Against this background it is possible that the nuclear enlargement present in toxic diffuse goitre reflects the disorder in itself and not the hyperfunctioning state. Hyperdiploid cell nuclei were found in all cases of toxic diffuse goitre and in a higher percentage than in the other lesions. It was not possible to distinguish nontoxic and toxic nodular goitre on this basis.