Lymphoma in 2 black vultures.

Vultures have suffered a drastic population decline mainly due to poisoning and traumatic lesions; neoplastic diseases in these birds are rarely documented. Here we describe the clinical and pathologic findings of lymphoma in 2 free-ranging black vultures (Coragyps atratus). Upon initial evaluation, both birds were severely emaciated; vulture 1 had proptosis of the right eye and vulture 2 swelling of the left wing. The vultures died shortly after presentation and were autopsied. In both birds, the thymus and many other organs were expanded by poorly demarcated, white, soft masses that were composed histologically of proliferating lymphocytes of monomorphic appearance. In vulture 2, thickening of the left-wing bones appeared to be caused by periosteal reaction, associated with bone invasion by the same type of lymphocytes, and granulomatous osteomyelitis. By immunohistochemistry, neoplastic cells were reactive for CD3 and negative for PAX5. The final diagnoses were multicentric T-cell lymphoma. PCR assays for Marek disease, avian leukosis, reticuloendotheliosis, and bovine leukemia viruses were negative in both cases. To our knowledge, lymphoma has not been reported previously in vultures.