Cytofluorimetric measurements on the DNA contents of tumor cells in human thyroid gland.

The relative DNA contents of thyroid cell nuclei were measured in surgically removed thyroid tissue of 50 patients by means of cytofluorimetry. Smears were prepared immediately after removal of the thyroid nodules according to the classical Feulgen technique. The fluorescence intensities were always compared with those of healthy thyroid tissue prepared in the same way. In each case samples were investigated by the usual histology. The observations indicate that differentiated carcinomas of thyroid gland have an increased DNA content of nuclei, at about the tetraploid level. Among them the follicular carcinomas (11 cases) showed an even higher DNA content of about 250% of the diploid level. Frequency distribution of the cell pools studied revealed a widely scattered aneuploidization of the malignant tumor cells. The benign adenomas displayed only a moderate increase of nuclear DNA content reaching only about 130% of the diploid value. Among the 22 adenomas classified histologically as of benign character, two cases showed very highly increased and widely scattered DNA contents. These latter two cases might be in process of malignant transformation. DNA cytofluorimetry may contribute to a more safe differential diagnosis of the "follicular neoplasia" of the thyroid gland.