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In this report, multiple abnormalities (bilateral ovarian cysts, cystic endometrial hyperplasia and pyometra (CEH-P), mammary adenoma, fibrosarcoma and cystic-papillary adenocarcinoma) identified in a queen continually administered medroxyprogesterone acetate (MPA) for 9 years are described. An 11-year-old domestic shorthair intact queen was presented for reduced appetite, polyuria, polydipsia, abdominal distension, and mammary mass. Pyometra was diagnosed based upon clinical, ultrasonographic and radiographic examinations. Mastectomy and ovariohysterectomy (OHE) were performed for treatment. Bilateral ovarian cysts were detected during OHE. Histopathologically, follicular ovarian cysts, CEH-P, and benign and neoplastic mammary lesions were identified. We suggest that, the pathological abnormalities may have been attributed to adverse effects of prolonged administration of MPA.

A 15-year-old female Holstein cow was presented with a history of anorexia and weight loss. Abnormal physical examination findings included poor body condition, dehydration, icterus, and photodermatitis on nonpigmented areas of the skin of the dorsum. At necropsy, the common bile duct was greatly enlarged, with thickened walls, and tightly adhered to the hepatic capsular surface and serosa of adjacent loops of the small intestine. Two sessile, yellowish, friable, well-circumscribed, cauliflower-like, bulging masses (14 and 8 cm in diameter) were attached to the inner surface of the common bile duct blocking its lumen. Microscopically, the tumor was composed of well-differentiated, columnar epithelial cells with oval or round, vesicular, basal nuclei arranged in papillary projections. Periodic acid-Schiff-positive material accumulated in the apical cytoplasm of the neoplastic cells. Immunostaining of the tumor cells was positive for cytokeratin (CK) of wide-spectrum screening and for CK 7. The diagnosis of papillary adenocarcinoma of the extrahepatic bile duct was based on the morphologic features of the neoplasm and evidence of local invasion. To the best of our knowledge, extrahepatic bile duct carcinomas have not been described in cattle.

Histopathologic and immunohistochemical examinations were performed on localized amyloidosis associated with mammary tumors in two dogs. These tumors were identified as adenoma and adenocarcinoma. An acellular, amorphous pale eosinophilic material (amyloid) was observed in the lumina of acini lined by neoplastic cells and in the stroma of the tumors. Concentrically laminated pale eosinophilic bodies (corpora amylacea) were also found in the lumina of the acini. Amyloid and corpora amylacea stained positively with Congo red with and without 5% potassium permanganate pretreatment and revealed a green birefringence under polarized light. Corpora amylacea showed an occasional Maltese-cross pattern. Immunohistochemically, amyloid and corpora amylacea usually stained positively with anti-bovine alpha-casein antibody but negatively with anti-human amyloid AA, anti-bovine kappa-light and lambda-light chains, anti-human lactoferrin, anti-human transferrin, anti-human secretory component, and anti-human polyglucosan antibodies. These findings suggested that the amyloid deposition in these canine mammary tumors was related to lactating casein.

As part of long-term pulmonary carcinogenesis studies in dogs, it is important to analyze the incidence of spontaneous lung neoplasia. Primary lung carcinoma incidence was determined in two control populations of Beagle dogs observed for their life spans. One population comprised 216 dogs (112 males and 104 females) that were controls for life span studies, and another comprised 182 dogs (50 males and 132 females) that were retirees from a breeding colony. Forty lung neoplasms were noted in the 398 dogs; 35 neoplasms were carcinomas classified as papillary adenocarcinoma (20), bronchioloalveolar carcinoma (9), adenosquamous carcinoma (5), or bronchial gland carcinoma (1). The other five neoplasms were a malignant fibrous histiocytoma, three adenomas, and a fibroma. The crude incidence of lung carcinomas averaged for both populations was 8.8% (35/398) and was dominated by a relatively high incidence of lung neoplasia in aged dogs, those dying after the median life span of 13.6 years.

The expression of epidermal growth factor receptor (EGF-R) was examined in canine lung tumors and in proliferative epithelial foci induced by plutonium-239 to determine if EGF-R was associated with specific neoplastic phenotypes or putative preneoplastic lesions. Seventeen (47%) of 36 canine lung tumors expressed EGF-R. Of these 17 tumors, three tumors hybridized with an erb-B RNA probe, which identified activated cell oncogenes. The expression of EGF-R was not correlated with tumor etiology, e.g., spontaneous versus radiation induced, but did correlate with specific histologic phenotypes. Nineteen (15%) of 127 proliferative epithelial foci in the canine lungs also expressed EGF-R. The phenotypic specificity demonstrated for EGF-R in canine lung tumors parallels that previously shown in human lung tumors. This finding, in addition to the identification of EGF-R in nonneoplastic proliferative lung lesions, indicates that radiation-induced lung tumors in the dog may be a useful animal model to investigate the role of EGF-R in lung carcinogenesis.

Twenty-two cases of intestinal adenocarcinoma were diagnosed in an 11-year survey of 3145 feline necropsies. Histologically, tumors were grouped into four classes: (1) carcinoma with solid groups of cells, (2) adenocarcinoma with solid and acinar cells, (3) papillary adenocarcinoma, and (4) mucinous adenocarcinoma. Tumors were commonest in the ileum. Connective tissue, as well as epithelial metaplasia, were associated more often in this group of intestinal adenocarcinomas nomas than seen before. Hypertrophy and hyperplasia of muscular layers of the unaffected sections of intestines were seen in most of the small bowel and in half of the large bowel carcinomas in this series.