Pathologic Features of Colorectal Inflammatory Polyps in Miniature Dachshunds

Abstract

The histopathologic characteristics of colorectal inflammatory polyps that formed in Miniature Dachshunds were compared with those of other colorectal proliferative lesions, including adenomas and adenocarcinomas. Fifty-three colorectal polypoid lesions were histopathologically classified into inflammatory polyps (26 cases), adenoma (18 cases), and adenocarcinoma (9 cases). All 26 dogs that were diagnosed with inflammatory polyps were Miniature Dachshunds, indicating that colorectal inflammatory polyps exhibit a marked predilection for this breed. The inflammatory polyps had complex histopathologic features and were classified into 3 stages based on their epithelial composition. In early stage (stage 1), the polyps tended to exhibit a thickened mucosa containing hyperplastic goblet cells, dilated crypts filled with a large amount of mucus, and mild lymphocyte and macrophage infiltration. In later stages (stages 2 and 3), more severe neutrophil infiltration, interstitial mucus accumulation, granulation tissue, and occasional osteoid tissue were seen. Also, a few small foci of dysplastic epithelial cells were detected. The hyperplastic goblet cells, which were a major component of the epithelium of the inflammatory polyps, were positive for cytokeratin 20 (CK20), while the dysplastic epithelial cells found in inflammatory polyps (stage 3) and the tumor cells of the adenomas and adenocarcinomas were negative for CK20. These CK20-negative epithelial cells exhibited cytoplasmic and nuclear immunoreactivity for beta-catenin. In addition, the epithelial cells in the inflammatory polyps demonstrated significantly higher cyclooxygenase 2 and fibroblast growth factor 2 expression than did those of the adenomas and adenocarcinomas, suggesting that the arachidonate cascade is involved in the development of colorectal inflammatory polyps in miniature dachshunds.

A histopathological study on spontaneous gastrointestinal epithelial tumors in dogs

“…The age and location of polypoid lesions in the present Jack Russell terrier cases were similar to those reported in human FAP 22,24,26 ; however, the high incidence of gastric tumors may be a characteristic unique to the breed of Jack Russell terriers. In contrast, the large intestine is of importance, while considering the tumorigenesis of gastrointestinal tumors in Miniature Dachshunds because the breed frequently develops inflammatory polyposis in the colorectum 27,28 . A previous study, by the authors, showed that inflammatory polyposis in Miniature Dachshunds may subsequently develop into adenoma or adenocarcinoma 29 adenocarcinoma, papillary adenocarcinoma, mucinous adenocarcinoma, signet-ring cell carcinoma, undifferentiated carcinoma and adenosquamous carcinoma 3 .…”

Expression of apical junction complex proteins in colorectal mucosa of miniature dachshunds with inflammatory colorectal polyps

“…The 8 MDs with ICRPs had been referred to Hokkaido University Veterinary Teaching Hospital for the investigation of hematochezia, tenesmus and an increased frequency of defecation and diagnosed with ICRPs based on clinical and histopathological findings of a previous report [13, 20]. They consisted of 5 males (2 intact and 3 neutered) and 3 females (2 intact and 1 neutered), and the median age of these dogs was 10 years (range, 9 to 14 years).…”

“…These 5 MDs consisted of 2 neutered males and 3 females (1 intact and 2 neutered), and the median age of these dogs was 9 years (range, 8 to 11 years). Inflamed mucosal lesions were staged (I-III) according to criteria adapted from those described previously [20]. Lesions in which >15, 5 -15 and <5% of the tissue consisted of epithelial cells were defined as stages I, II and III lesions, respectively (Fig.…”

“…ICRPs are characterized by the formation of multiple small polyps around the large bowel mucosa, almost invariably restricted to the descending colon and rectum, sometimes accompanied by space-occupying solitary large polyp formation. Histopathological findings of ICRPs are proliferative changes of epithelium without cellular atypia, increased goblet cells with dilated crypts, the infiltration of inflammatory cells (predominantly by neutrophils and macrophages) and proliferation of granulation tissue [13, 20]. MDs with ICRPs show a good response to immunosuppressive drugs, such as prednisolone, cyclosporine and leflunomide [6, 13].…”

Adenocarcinoma of Barrett’s esophagus in a dog

“…The CK expression of Barrett’s esophagus is characterized by diffuse CK7 staining and surface staining of CK20 14 , which were also observed in the present canine case. CK20 is a marker of differentiated intestinal epithelial cells, and its expression is decreased in the esophageal and intestinal adenocarcinoma cells of humans and dogs 15 , 16 .…”