DNA ploidy and nuclear morphometric variables for the evaluation of melanocytic tumors in dogs and cats

Objective-To determine the prognostic importance of the DNA content and nuc lear morphometric variables in melanocytic tumors of cats and dogs. Sample Population-27 melanocytic tumors of dogs and cats. Procedures-Biopsy specimens were investigated by quantitative image analysi s after the Feulgen staining method. The DNA content (index), nuclear diame ter, ploidy balance, proliferation index, hyperploidy, and growth fraction (Ki67) were measured. Using 1-way ANOVA and a Pearson correlation test, the relationships between the different variables were tested. Their role in t he prognosis in affected dogs and cats was estimated using the Cox regressi on test with respect to 6 months postoperative survival rate. Results-Significant correlations were found between DNA index and ploidy ba lance and proliferation index. A significant correlation was also found bet ween hyperploidy and DNA index, and between ploidy balance and proliferatio n index. Significant differences were four-id between histologically malign ant and benign melanocytic tumors but not between primary malignant tumors and metastatic malignant tumors for DNA index and ploidy balance. No correl ation was found between DNA variables and survival time. Conclusion and Clinical Relevance-In melanocytic tumors of cats and dogs, D NA index and ploidy balance can be used to differentiate histologically ben ign from malignant tumors. However, DNA content and nuclear morphometric va riables have little value in predicting survival time. The DNA index and pl oidy balance provide an additional tool to evaluate melanocytic tumors of c ats and dogs. Survival in dogs and cats with melanocytic tumors, however, i s not determined by modifications of DNA content or changes in nuclear morp hometry of tumor cells.