Correlation between DNA Ploidy and Activity of Proliferating Cell Nuclear Antigen (PCNA) in a Dog with Well Differentiated Squamous Cell Carcinoma

Paraffin-embedded tissue sections of surgically removed skin tumor from an eight-year-old male Shih-Tzu dog were analyzed for proliferation state using immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and for DNA ploidy using flow cytometry. Histologically, tumor was diagnosed as well differentiated squamous cell carcinoma. The percentage of PCNA-positive cells, which distributed through tumor lesions, was 61.4%. In addition, PCNA-positive cells in the cancer pearls were detected only at the periphery of the neoplastic epithelial structures. The ploidy of this tumor detecting by DNA flow cytometry was clearly aneuploid. From these results, the proliferation state of this tumor determined by PCNA-immunostaining and DNA ploidy revealed malignant, even this tumor was diagnosed as well differentiated squamous cell carcinoma.