Samples of liver, kidney, spleen, and hepatic, mesenteric, retromandibular, prescapular and mediastinic lymph nodes, collected from 12 groups of cattle of different ages from the State of Mato Grosso, were studied. A total of 120 bovines was examined. According to their history, the animals were kept in pastures where Brachiaria decumbens and Brachiaria brizantha were the predominant plants. Grossly there was a yellowish liver which was more evident after 24 hr. fixation with formalin. Hepatic and mesenteric lymph nodes had normal size, however, on the cut surface there were whitish grooves, extending from the cortex to the medular, and multiple small white nodular areas in the medular. Beside these areas there were red, sometimes hemorrhagic, foci. Microscopically all animals had cells with foamy citoplasm in the liver and in the hepatic and mesenteric lymph nodes, often forming multinucleated cells. In the lymph nodes these infiltrates were adjacent to necrotic, hemorrhagic areas. In the liver the foamy cells were irregularly disseminated throughout the parenchyma or formed nodules around the central vein. These cells did not stain with PAS but weakly with oil red. Ultrastructurally foamy cells and hepatocytes showed negative images of crystals involved partially or totally by membranes. Mediastinic, retromandibular and prescapular lymph nodes of the same animals showed no gross and microscopic alterations.
Foamy macrophages; granulomatous lymphadenitis; liver lesions; Brachiaria spp; cattle
