Histopathological , Enzyme - Histochemical and Immunohistochemical Diagnosis of Mast Cell Tumors in the Skin of Golden Hamster

No previous records in the available literature about the cutaneous mast cell tumors in golden hamster. Two male golden hamsters with cutaneous lumps were brought to the Institute of Veterinary Pathology of Justus Leibig University of Giessen, Germany for diagnositic examination. Cutaneous lumps were taken and processed for histological, histochemical and immunohistochemical examination. Numerous oval and polygonal tumor cells with high mitotic count and basophilic metachromatic granules were observed; while the superjacent epidermis and adnexes were normal. Many unevenly proliferating cells showed positive proliferating cell nuclear antigen (PCNA) reaction and positive chymase activity. The reactions were negative to gene encoding KIT (c-Kit), Cyclooxygenase-2 (COX-2) and tryptase. These results indicated a well- differentiated grade I subcutaneous mast cell tumor. The results are discussed in relation to subcutaneous mast cell tumors in canines.