RESUMEN
Some papillary carcinomas of thyroid glands contain not only typical papillary structures but also various histological features in the same tumor. To investigate how areas with variable histological features differ in proliferative activity and how these differences influence the biological behavior of the whole tumor, we measured DNA contents by cytofluorometry in six papillary carcinomas with different histological features in the same tumor. DNA ploidy patterns were determined and the percentage of S plus G2M phase cells (S + G2M fraction) was calculated only in diploid tumors to assess the proliferative activity. The following conclusions were drawn. 1) It was demonstrated that there were differences in proliferative activity among areas with variable histological features in 4 of six tumors. 2) In the tumors which invaded adjacent tissues, the proliferative activity of the invasive area tended to be higher than that of the original area of the tumor. Therefore, the possibility exists that more precise evaluation of the biological behavior of the tumor can be obtained by measuring DNA contents of the tumor cells in invasive areas. 3) There was the gap in S + G2M fractions among some tumors with the same histological differentiation. Accordingly, DNA analysis of tumors would be of value in estimating proliferative activity.
