Morphological, histopathological and immunohistochemical study of canine malignant lymphoma

Lymphoid tumours comprise one of the most common groups of tumours in dogs and there was considerable confusion with regard to their nomenclature and classification. A new classification of lymphoid neoplasm was proposed by the International Lymphoma Study Group and is accepted as the Revised European American Lymphoma Classification-R.E.A.L. Classification. These tumours are divided into three major categories: B cell neoplasm, T cell and natural killer neoplasm and Hodgkin's disease. Canine malignant lymphoma was detected 11 cases out of 119 dogs of different age, sex and breed, necropsied in the last two years at the Department of Pathology, Faculty of Veterinary Medicine, Belgrade. According to the anatomical classification, three different forms of lymphoma were seen: the most frequent form was multicentric (8 of 11 cases), followed by alimentary form (2 of 11 dogs) whereas cutaneous lymphoma occurred in 1 dog. Histologically, three different forms of lymphoma were found: poorly differentiated (in 6 cases), intermediate (in 4 cases) and well differentiated (in 1 case). By immunohistochemical demonstration of CD79, CD3 and MAC-387, we showed that B-cell lymphomas were predominant (8 of 11 cases), while T cell lymphomas were demonstrated in 3 cases.