Feline Hodgkin's-like lymphoma: 20 cases (1992-1999)

We identified 20 cases of feline lymphadenopathy that conform to many clini cal and histologic manifestations of human Hodgkin's disease. Histologic su btypes encountered included lymphocyte predominance (nine cases), mixed cel lularity (nine cases), and nodular sclerosis (two cases). Two cases were no t easily classified; fibrous bands were present, but the absence of nodules supported a subclassification of mixed cellularity Hodgkin's disease. Immu nohistochemical staining of the tissues using antibodies against the pan T- cell antigen CD3, the human B-lymphocyte antigen 36 (BLA.36), the pan B-lym phocyte and plasma cell marker CD79a, and a myeloid antigen (MAC387) confir med the phenotypic heterogeneity of the tumor. Classic Reed-Sternberg (RS) cells and mononuclear, multinucleate, and lacunar cell variants did not sta in with any of the antibodies used. In contrast, lymphohistiocytic RS varia nts (L+H cells) reacted positively to BLA.36 and CD79a B-cell markers. Eigh teen of 20 affected cats were greater than or equal to6 years of age (range , 1-14 years). A sex predilection could not be identified. These findings s upport the existence of Hodgkin's-like lymphoma in the cat. Proper identifi cation of this disease in the cat will enable further characterization of c linical features and biologic behavior to determine whether there are signi ficant differences in the treatment and prognosis of feline Hodgkin's-like lymphoma compared with non-Hodgkin's lymphoma.