Expression pattern of proliferating cell nuclear antigen (PCNA) in round cell tumors of dogs from Grenada, West Indies

A retrospective study was performed on archivedtumor tissues received by the Veterinary Pathology Diagnostic Laboratory, School of Veterinary Medicine, St. George's University, Grenada over an 11 year period (2001–2011). The expression pattern of proliferating cell nuclear antigen (PCNA) was evaluated in canine round cell tumors. A total of 40 tumors comprising of transmissible venereal tumor(TVT), canine cutaneous histiocytoma(CCH)and mast cell tumor(MCT) were evaluated for PCNA expression using immunohistochemistry technique. Moderate to strong immunoreactivity was detected in most of these tumors. The percentage of immunomarked cells for PCNA was 42.1, 57.1, and 57.1 for TVT, CCH, and MCT, respectively. A statistical significance (P<0.05) between the average mitotic counts and PCNA expression for TVT and CCH was noted. PCNA expression in the TVT cases ranged from 17.4% to 56.3% which suggests the presence of variable growth fraction in this tumor. The results showed that PCNA immunohistochemistry could be an important adjunct tool in determining the biological behavior of round cell tumours.