Pathology in Practice
Journal of the American Veterinary Medical Association
Sections of various tissues, including rumen, reticulum, omasum, abomasum, heart, liver, and lungs, were prepared for histologic examination. No important microscopic abnormalities were noted in sections of rumen, reticulum, omasum, abomasum, and heart. The cysts in the lung and liver tissues were identified as the larval stage of a tapeworm (metacestodes). In lung sections, multiple metacestodes replaced portions of entire lobes. The metacestodes consisted of a thick outer layer of laminar acellular material that rested on a layer of simple squamous germinal epithelium (Figure 2). Adjacent to the germinal epithelium were multiple, encapsulated protoscolices, which lacked a body cavity but had armed scolices (brood capsules; Figure 3). Thick bands of fibrous tissue surrounded each metacestode, and epithelioid macrophages frequently infiltrated outermost collagen fibers. Adjacent pulmonary lobules were compressed and infiltrated with numerous macrophages and lymphocytes. Peribronchiolar lymphoid follicles were large and densely cellular. In the liver, metacestodes similar to those in the lung replaced numerous contiguous lobules. In addition, there were multifocal, randomly distributed foci of hepatocellular necrosis infiltrated with moderate numbers of neutrophils. Overall, the characteristics of the metacestodes were consistent with the larval stage of Echinococcus granulosus.
Kelly, E.J., T. Baldwin, and K.A. Rood. (2012) Echinococcus granulosus infection in a Utah sheep in Pathology in Practice. December 1, 2012, Vol. 241, No. 11, Pages 1449-1451. doi: 10.2460/javma.241.11.1449