Abstract
Leukoproliferative diseases are common in cats and involve a variety of cell types. One such disorder, an anatomical entity of unknown etiology, is characterized by severe progressive anemia and proliferation of undifferentiated (reticulum) cells in bone marrow, spleen, liver and lymph nodes. Malignant behavior of the abnormal cells is not obvious, and the descriptive term, reticuloendotheliosis, is suggested for the disorder until the etiology is known.
Clinical, hematologic and post mortem findings in 10 cats with reticuloendotheliosis are compared in this report with those in 10 cats with lymphocytic leukemia. Clinical findings are not distinctive and are similar in both conditions, but the diseases can be distinguished by hematologic and post mortem studies. Cats with reticuloendotheliosis are characterized by persistence of totally undifferentiated cells in the peripheral blood and bone marrow. Between 15.7 and 76.8% of these cells were found in the bone marrow and up to 55% in the peripheral blood. No intermediate stages, suggesting development toward a more specific cell type, were found.
Gross findings at necropsy in cats with reticuloendotheliosis were anemia and enlargement of the spleen, liver and lymph nodes. Reticulum cells were diffusely distributed in vascular or lymphatic spaces in each of these organs. The cells were individually discrete and did not form solid masses.
Cats with lymphocytic leukemia had high proportions of lymphocytic cells in the blood and bone marrow. The neoplastic cells obliterated the normal architecture of lymph nodes and frequently formed solid masses in other tissues.
Hematologic and post mortem findings in some previously reported cases of leukemia in cats which were characterized by proliferation of poorly differentiated cells have some similarities to those in cases of reticuloendotheliosis.