IMAGE-ANALYSIS EVALUATION OF PLOIDY, S-PHASE FRACTION AND NUCLEAR-AREA IN CANINE MAMMARY-TUMORS

Image analysis was used on cytocentrifuge preparations of Feulgen-stai ned nuclei extracted from formalin-fixed, paraffin wax-embedded tissue s to determine ploidy (assessed by integrated optical density), S-phas e fraction, and nuclear area of 90 canine mammary tumours (30 benign a nd 60 malignant). Only two lesions identified histologically as benign were aneuploid, suggesting potential malignancy. Of malignant tumours , 37% were aneuploid. No distinction based on ploidy could be made wit hin benign or malignant groups, except for tubular adenocarcinomas of complex type, all of which were diploid. Mean S-phase fraction of mali gnant lesions (15.60%) was twice that of benign lesions (7.87%; P<0.00 01). The mean nuclear surface was significantly smaller in malignant l esions (70.62 mu m(2)) than in benign counterparts (77.45 mu m(2) P<0. 05). No relation was found between a given tumour type and S-phase fra ction or nuclear area within histologically malignant or benign tumour groups. Infiltration of lymphatics by neoplastic cells, known to indi cate a poor prognosis, was associated with aneuploid lesions (mean DNA index >1.25) and high S-phase fraction. The presence of necrosis and of a high number of mitoses was significantly associated with high S-p hase fraction lesions. (C) 1995 Academic Press Limited