The use of immunomarkers in diagnosis of round cell tumors of DOGS

"Round cell tumor" localized in skin tissue of dog is called as "skin round cell tumor" in main classification because of their small, discrete (individualized), and round morphological characters. These tumors consisted of histiocytoma, mast cell tumor, transmissible venereal tumor (TVT), cutaneous lymphosarcoma, melanoma, plasmacytoma and neuroendocrine cell tumor. The aim of the present study is to carry out classification of skin round cell tumors of the dog in archive of department of pathology, faculty of veterinary medicine, Adnan Menderes University, using histopathology, histochemistry and immunohistochemistry. The study materials consisted of 24 cases with round cell tumors diagnosed between 1999-2015 in department of pathology, faculty of veterinary medicine, Adnan Menderes University. The sections prepared from these paraffin tissue samples were stained with haematoxylin-eosin and giemsa. Immunohsitochemically, the sections were stained with avidin-biotin peroxidase complex method with c-KIT, tryptase, CD1a, MHC-II and vimentin primary antibodies. The results were evaluated to classification of WHO-AFIP (World Health Organiztion–Armed Forces Institute of Pathology). Histology and immunohistochemistry showed transmissible venereal tumor (4 cases), mast cell tumor (13 cases) and histiocytoma (11 cases). Immunohistochemically, mast cell tumors expressed mainly c-KIT and, to lesser extend, tryptase; histiocytic tumor cells expressed mainly tryptase and MHC-II; TVT expressed tryptase, MHC-II and vimentin. However, immunohistochemistry represented no expression of CD1a, which is derived from antigen of human cell. In conclusion, histomorphologic findings of round cell tumor was not sufficient for differentiation. For this reason, immunomarkers were necessary for certain diagnosis of these tumors.