DNA IMAGE CYTOMETRY ON SECTIONS AS COMPARED WITH IMAGE CYTOMETRY ON SMEARS AND FLOW-CYTOMETRY IN MELANOMA

DNA measurements of 130 melanomas were carried out by flow cytometry ( FCM) and image cytometry (ICM). ICM was applied to cytological prepara tions of fresh material (cICM) and to sections of formalin-fixed paraf fin embedded tissue (sICM). The DNA ploidy, the DNA index of G0/G1 pea ks (DI), and the proliferation index (PI) were used to compare all the methods. The following parameters reflecting malignancy were calculat ed only from ICM histograms: the 5c exceeding rate (5cER) and the mali gnancy grade (MG). In cases found to be DNA aneuploid by FCM, the PI v alues (FCM versus cICM) and the DIs (between all methods) showed a hig h correlation, and the concordance in relation to the DNA ploidy statu s was 96% (FCM versus cICM) and 94% (FCM versus sICM). However, we asc ertained essential differences between FCM and ICM in melanomas classi fied as DNA diploid by FCM. The concordance in DNA ploidy was only 66% (FCM versus cICM) and 64% (FCM versus sICM). In contrast, cICM and sI CM yielded similar results in most cases. With the exception of the ne ar diploid range, ICM is superior to FCM in detecting DNA aneuploidy. In particular, DNA tetraploid stem Lines can easily be overlooked by F CM. Therefore, DNA measurements of tumours judged to be DNA diploid by FCM must be verified by ICM. ICM on sections proved to be applicable and yielded reliable results provided that a suitable thickness was us ed, and the measuring of sectioned and overlapping nuclei was largely avoided by careful focusing in either direction. (C) 1996 Wiley-Liss, Inc.