T-cell-rich B-cell lymphoma in a ring-tailed lemur (Lemur catta)

A 13-yr-old ring-tailed lemur (Lemur catta was evaluated for depression, an orexia, polyuria, and poly dipsia. The lemur was in poor body condition and was anemic, hypoalbuminemic. and hyponatremic. Cytologic examination of as pirates of the spleen, liver, and bone marrow and histopathologic examinati on of liver and bone marrow biopsies revealed a disseminated round cell tum or. After euthanasia, necropsy revealed hepatomegaly, splenomegaly, and mes enteric lymphadenomegaly. Neoplastic cells were present within the spleen, liver kidneys, multiple lymph nodes, bone marrow, lung, small intestine, pa ncreas, and testicle and were composed of large anaplastic round cells in a background of small well-differentiated lymphocytes. Immunohistochemical a nalysis revealed that the small well-differentiated lymphocytes labeled for the anti-human T-cell marker, CD3, and the large anaplastic round cells la beled with the anti-human B-cell marker. CD79a. On the basis of the immunoh istochemical staining results and morphologic appearance, a diagnosis of a T-cell-rich B-cell lymphoma was made.