A comparative study of DNA cytometry methods for benign and malignant thyroid tissue

DNA measurements of 46 thyroid specimens were performed by use of fresh tissue for flow cytometry and formalin-fixed paraffin-embedded tissue for flow and static cytometry. The tissue included four histopathologic subgroups, i.e., 19 colloid goiters, 7 papillary carcinomas, 10 follicular adenomas, and 10 follicular carcinomas. The methods measured DNA index and the percentage of cells in S-phase for each subgroup. There was a strong correlation between the methods for DNA-index measurements. In three cases, tissue interpreted as diploid by one method was aneuploid by another method. The S-phase measurements were not reproducible between the methods because of the low percentage of cells in S-phase (mean: 2.6%; range: 0.0-7.5% overall). Aneuploid cells were rare in nodular goiter (2 of 19 cases, 10.5%) but were increasingly present in subsequent subgroups, i.e., 2 of 7 papillary carcinomas (28%), 3 of 10 follicular adenomas (30%), and 6 of 10 follicular carcinomas (60%).