cells with anisocytosis, anisonucleosis, multiple nuclei,. Departamento de Patologia, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional ...
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Concurrent cholangiocarcinoma, peritonitis, paratuberculosis, and aspergillosis in a goat Maria C. Dominguez, Gilberto Chavez, Francisco J. Trigo, Maria L. Rosales A7-year-old, female Sannen without a prior history of illness, but in poor condition, was submitted to the Pathology Department of the College of Veterinary Medicine for postmortem examination. The animal was from a flock involved in an experimental program for the control of paratuberculosis. Postmortem examination was performed 2 h after death. At necropsy, the abdomen contained approximately 2 L of green-tinged, cloudy exudate and fibrin sheets. The liver was slightly green with a well delineated, 15-cm long saccular structure over its visceral surface, between the right and left lobes. This sac invaded the hepatic parenchyma, had a red and ragged surface, was surrounded by fibrous tissues, and contained copious amounts of fluid similar to that in the abdominal cavity. Adjacent bile ducts were thickened and surrounded by abundant connective tissue. On cross-section, the hepatic parenchyma near the sac was replaced by multiple white, firm, well-delineated nodules up to 6 cm in diameter (Figure 1). Some of the nodules had central necrosis and hemorrhage. The mucosa of the small intestine appeared irregularly thickened, while the right diaphragmatic pulmonary lobe had 2 solid white nodules, each 0.5 cm in size. No gross lesions were observed in other organs. Segments of liver, intestine, and lung, were fixed in 10% neutral buffered formalin, embedded in paraffin wax, and cut into 4-,um sections, which were stained with hematoxylin and eosin (HE), periodic acid-Schiff (PAS), PAS-alcian blue at pH 2.5, and Ziehl-Nielsen for light microscopic examination. Segments of liver for electron microscopy were fixed in 2.5% cacodylate-buffered glutaraldehyde, postfixed in osmium tetroxide, and embedded in epoxy resin. Ultrathin sections were cut and placed on copper grids and then stained with uranyl acetate and lead citrate. All sections were examined by electron microscope. By light microscopy, the liver masses consisted of numerous irregular proliferating ducts and gland-like structures. In some areas, these gland-like structures were lined by a single layer of cuboidal epithelial cells with oval basal nuclei and prominent nucleoli. In other areas, the glands were lined by several layers of pleomorphic cells with anisocytosis, anisonucleosis, multiple nuclei, Departamento de Patologia, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Aut6noma de Mexico, Ciudad Universitaria, Coyoacan, D.F., 04510 Mexico. Address correspondence to Dr. M.C. Dominguez. This work was supported by Grant 25395-B CONACyT, Mexico. 884
Figure 1. Liver. Cut section of a neoplastic nodule showing a white, firm, well-delineated mass.
Figure 2. Liver. A neoplastic, dilated gland with reactive epithelium and debris and hyaline material in the lumen. Fibrous stroma is a prominent feature around the neoplastic ducts. Hematoxylin and eosin: bar = 20 ,um.
and atypical mitosis. Occasional cysts with stratified epithelium forming luminal papillae and intraluminal cellular debris, mucous-like fluid, and neutrophils were identified (Figure 2). Neoplastic cells were positive for PAS-alcian blue stain (indicating acid mucin) at the apical cell surface, while the cytoplasm was negative. Other findings in the hepatic parenchyma included invasion of neoplastic cells into the stroma, large areas of necrosis, cholestasis, centroacinar fibrosis, and infiltration by lymphocytes. The walls of the saccular structure were not very well preserved, except for some cuboidal epithelium, foci of necrosis, fibrosis, and neutrophilic infiltrates in adjacent parenchyma. Can Vet J Volume 42, November 2001
Ultrastructural studies confirmed the epithelial histogenesis of this tumor. The well-differentiated cuboidal cells were linked by desmosomes, delimited by a continuous basal membrane, and covered by microvilli at the apical surface. Membrane-bound mucin granules near the cell membrane, swollen mitochondria, and intermediate filaments, but few other organelles, were identified in the cytoplasm. The nuclei had numerous surface invaginations, multiple nucleoli, and clumped chromatin. At the cystic areas, the papillary cells were columnar, with oval basal nuclei. Fibroblasts were common throughout the tumor. Based on morphology, this tumor was classified as a cholangiocarcinoma. The serosa of the intestines and liver, as well as the peritoneum, was severely thickened with proliferation of fibroblasts and infiltrated by many macrophages, neutrophils, lymphocytes, and fibrin, compatible with peritonitis. The intestine had many small granulomata, with foamy macrophages and lymphocytes in Peyer's patches and adjacent mucosa. Staining with Ziehl-Nielsen revealed infrequent acid-fast bacilli in macrophages, findings typical of paratuberculosis. Diagnosis was confirmed by isolation of Mycobacterium avium subsp. paratuberculosis in Lowenstein-Jensen medium with mycobactin. In addition to numerous intravascular microthrombi, several small inflammatory foci were found in the lung. These foci contained many dichotomous, branched hyphae, surrounded by a rim of macrophages, lymphocytes, and neutrophils. The hyphae were morphologically compatible with Aspergillus fumigatus. The presentation of this case was unusual due to the concurrence of cholangiocarcinoma, peritonitis, paratuberculosis, and aspergillosis. The cause of death appeared to be peritonitis, secondary to the cholangiocarcinoma. Based on the histopathologic findings, the saccular structure in the liver appeared to originate as a bile duct that was progressively occluded by neoplasia and fibrosis. Subsequently, rupture of the bile duct induced peritonitis that was followed by septic shock and pulmonary microthrombi. Although aspergillosis can cause vascular damage in the lung of ruminants, the small number of foci observed in this case is not consistent with the diffuse distribution of microthrombi throughout the lung. The paratuberculosis lesions were considered to be responsible for the animal's poor condition, but they were
Can Vet J Volume 42, November 2001
also considered to be a coincidental and expected finding due to the history of this herd. Although infrequent, hepatic tumors that have been reported in the goat include cholangioma (1), hepatocellular carcinoma (2), and cholangiocarcinoma (3). In humans, this tumor has been associated with viruses, chemical carcinogens, mycotoxins, and drugs (4). As in other reports in the goat, the cause of this tumor could not be established. Histopathologic and ultrastructural findings in this case were similar to those previously described. Neoplastic cells in cholangiocarcinomas typically form irregular gland-like structures surrounded by a prominent connective tissue stroma (3), but cysts and papillae are inconsistent findings. Ultrastructural studies have not been done previously in a cholangiocarcinoma in a goat. Except for the lack of abundant mucin and intracellular lumens, this case shared most of the ultrastructural features described for this tumor in humans (5). Overall, this case highlights an unusual concurrence of a tumor and coincidental infections, where a secondary obstructive process rather than the primary tumor was the cause of death.
Acknowledgments The authors would like to thank Dr. Marcelo de las Heras from the School of Veterinary Medicine, Zaragoza, Spain for his helping in obtaining some of the references. This work was supported by Grant 25395-B CONACyT, Mexico.
References 1. Puette M, Hafner H. Cholangioma in a goat. J Vet Diagn Invest
1995;7:574-575. 2. Lairmore MD, Knight AP, De Martini JC. Three primary neoplasms in a goat: Hepatocellular carcinoma, phaechromocytoma and leiomyoma. J Comp Pathol 1987;97:267-271. 3. Rodriguez F, Herraez P, Rodriguez JL, Or6s J, Zaera JP, Espinosa de los Monteros A. Cholangiocarcinoma in a goat. Vet Rec 1996; 139:143-144. 4. Kelly RW. The liver and biliary system. In: Jubb KVF, Kennedy PC, Palmer N, eds. Pathology of Domestic Animal. San Diego: Academic Pr, 1993:404. 5. Erlandson E. Ultrastructural features of specific human neoplasms with clinicopathologic, immunohistochemical, and cytogenetic correlations. In: Stemnberg S, ed. Diagnostic Transmission Electron Microscopy of Human Tumors. New York: Masson Publ Inc, 1981:99-103.
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