Eosinophilic leukemia in a Syrian hamster.

Abstract

A male Syrian golden hamster, part of a lifetime lung-carcinogenesis bioassay that used benzo (a) pyrene-hematite, was routinely examined at death for lung tumors. The hamster was 92 weeks old at death. There was a diffuse gray-white mass in the chest cavity. It involved three of the five lung lobes and had infiltrated the pericardium partially around the heart. The bronchial lymph nodes were enlarged and gray-white. Many small red dots, indicative of the benzo (a) pyrene-hematite, were visible on the lung surfaces. The liver had an accentuated lobular pattern with an occasional prominent circumscribed gray-white area. The intestines seemed normal, except for a focal thickening in the lower jejunum and lower bowel. Other organs and tissues seemed normal. The heart, lungs, trachea, liver, kidney, spleen, intestines, brain, gonads and femur were placed in 10 percent neutral buffered formalin, processed routinely and stained with hematoxylin and eosin . The tumor mass consisted of a scant loose stroma with many immature granulocytic cells. The cells looked the same in all tumor infiltrates but varied in extent from organ to organ. The lungs had extensive tumor infiltrates. Vascular cuffs of tumor cells were common, and many masses were in the parenchyma. Some extended beyond the surface of the lung, and some appeared as isolated nodules. In affected lobes, the blood vessels were engorged with tumor cells. Focal aggregations of hematite-filled macrophages, associated with the carcinogen treatment, were distributed randomly throughout the parenchyma; multiple focal areas of bronchiolar adenomatoid lesions were in some lung lobes. Focal areas of tumor were under the tracheal carina and the bronchial nodes were filled with tumor cells. The heart was partially surrounded by a large mass of tumor cells. The mass had partially destroyed the epicardium on the left ventricle and had infiltrated the cardiac musculature. The kidneys had moderate tumor infiltrates at the hilus immediately under the epithelium. Occasionally small focal nodules of neoplastic cells were in the cortex. The liver contained numerous periportal aggregations of neoplastic cells (fig. 1). The aggregations varied in size; some extended into the hepatic parenchyma. The