Analysis of karyometric variables in spontaneously occurring canine mammary tumors.

Abstract

OBJECTIVE: To study alteration in karyometric variables to distinguish benign from malignant canine mammary tumors. STUDY DESIGN: Formalin-fixed, paraffin-embedded tissue sections from 16 cases of canine mammary tumors were stained with hematoxylin-eosin and analyzed for mean nuclear area, mean nuclear perimeter and shape factor. The morphometric descriptors were then correlated with conventional histologic diagnosis. RESULTS: On Mann-Whitney U-test, nuclear variables, that is, mean nuclear area and mean nuclear perimeter, revealed significant difference between malignant and benign groups (p < 0.01), while shape factor showed significant difference at p < 0.05. All morphometric descriptors showed significant correlation with each other and with histopathologic diagnosis. Contrary to expectations, shape factor was lower in benign compared to malignant tumors. In benign mammary tumors, the highest mean nuclear area and perimeter were 39.59 +/- 10.34 microm2 and 25.39 +/- 4.14 microm, respectively, for fibroadenoma; and in malignant tumors the highest mean nuclear area and perimeter were 48.44 +/- 12.89 microm2 and 27.36 +/- 4.31 microm, respectively, for papillary adenocarcinoma. CONCLUSION: This study provides insight into the alterations in karyometric variables in canine mammary tumors. Mean nuclear area and perimeter appear to have potential to differentiate benign and malignant canine mammary tumors.