Abstract
Lymphoid neoplasms, which were found in 59 cattle infected with bovine leukosis virus (BLV), were examined through histology and immunohistochemistry. Fifty-six cases were found to have CD20- and CD79a-positive pleomorphic B-cell lymphoma, characterized by cytological pleomorphism and atypia. Tissue sections suitable for CD5 immunostaining were obtained from 54 cases, all of which were found to be positive for this marker. In one case of a pregnant cow, the fetus had pleomorphic lymphoma lesions in the subcutis. This was interpreted as resulting from a metastasis of the maternal lymphoma. The remaining three cases, which were diagnosed as precursor B-lymphoblastic leukemia, lymphoplasmacytoid lymphoma and γδT-cell lymphoma, were distinct from the pleomorphic lymphoma in cytology and immunophenotype. Because such histological types are chiefly observed in BLV-negative cattle, these cases were presumably not associated with BLV. The present study indicates that bovine lymphoid neoplasms are classifiable into histologically and immunohistochemically discrete disease entities.
