Ki-67 positive fractions in benign and malignant thyroid tumours: Application of flow cytometry

We investigated the DNA ploidy pattern. cell cycle and the percentage of Ki -67 positive fractions in Fresh surgical material from 17 benign and 33 mal ignant thyroid tumours using flow cytometry. DNA aneuploidy was not seen at all in benign tumours. but was seen in 3 out of 33 malignant rumours. sugg esting that detection of DNA,4 aneuploidy indicates malignancy, although th e detection sensitivity was low. Regarding the cell cycle. there was no dif ference in the percentage of S-phase fractions (SPF) or G2 plus M phase fra ctions (G2M) between benign and malignant rumours. However. the percentage of Ki-69 positive fractions in malignant rumours (39.9 +/- 3.9) was signifi cantly higher than that in benign rumours (9.4 +/- 2.1%,), indicating that malignant thyroid rumours contained a large population of G1 phase cells. W hen a cut-off value of 20%; was used for Ki-67 positive Fractions. sensitiv ity was 82%;, specificity was 88% and accuracy was 84% fur the diagnosis of malignant tumours. Although this study was carried our on surgically deriv ed marerials, it is possible that flow cytometric analysis of fine needle a spiration-derived materials may have a place in preoperative histopathologi cal assessment of thyroid tumours.