Today's Veterinary Practice

JAN-FEB 2018

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PEER REVIEWED 94 IMAGING ESSENTIALS In cats, common intestinal tumors include lymphoma and adenocarcinoma. Mast cell tumor and hemangiosarcoma have also been reported in the cat. 44-47 Multicentric small intestinal neoplasia, particularly lymphoma, has moderately to severely thickened walls 53 with muscularis layer thickening ( FIGURE 20 ). 54 Muscularis layer thickening is not definitive in diagnosing infiltrative neoplasia as it is also seen in cats with inflammatory bowel disease; however, it has been determined that the odds are high for a cat with muscularis thickening to have lymphoma. 54 Thickening of the muscularis may be explained by the fact that lymphoma commonly occurs in conjunction with inflammatory bowel disease in cats, 54 as chronic gastrointestinal inflammatory processes in cats can transform to develop subsequent gastrointestinal lymphoma. 55 Additional imaging findings of lymphoma include circumferential, homogeneous, hypoechoic thickening of the small intestinal walls with a loss of normal wall layering; 45 regional, moderate, hypoechoic lymphadenopathy is generally present ( FIGURE 21 ). A complication of infiltrative intestinal neoplasia includes mechanical obstruction due to intraluminal narrowing. Common inflammatory bowel diseases, such as lymphocytic-plasmacytic enteritis, are usually associated with mild to moderate wall thickening affecting several or all intestinal segments with variable severity. Other ultrasonographic features of intestinal inflammatory diseases include circumferential, mild to moderate wall thickening affecting primarily the mucosa, submucosa, and/or muscularis layers ( FIGURE 22 ); 54 diffuse increased echogenicity of the mucosa; or the presence of bright mucosal speckles. 45,56 The bright mucosal speckling has been postulated to represent a section through dilated lacteals or focal accumulation of mucus, cellular debris, proteins, and/or gas within the mucosal crypts. 57 There is significant overlap between the ultrasonographic appearance of inflammatory bowel disease and small cell lymphoma in cats, and the differentiation between these two entities is often impossible based on ultrasound findings alone. 53,54 The presence of large, rounded hypoechoic mesenteric lymph nodes should be evaluated for potential multicentric disease (lymphoma or pythiosis) or metastatic disease (adenocarcinoma). In dogs, intestinal tumors have significantly greater wall thickness, loss of wall layering, and more focal lesions than seen with enteritis. 45 However, the absence of wall thickening does not completely rule out inflammatory disease as the correlation between wall thickness and histopathological diagnosis of inflammatory bowel disease in dogs have not been seen. 58 To obtain a definitive diagnosis, histopathology of the affected area is required. 59 SUMMARY A systematic examination of the gastrointestinal tract is a routine part of the complete ultrasonographic abdominal evaluation. In Part 1 of the gastrointestinal tract, the normal and common abnormal ultrasound findings of the stomach, duodenum, and jejunum have been presented. The ileum, cecum, and colon will be addressed in Part 2. FIGURE 22. Longitudinal axis view of a segment of jejunum of a cat diagnosed with histopathologically confirmed inflammatory bowel disease. Note the mild, diffuse thickening of the wall, measuring 0.3 cm in thickness, with thickening of the muscularis layer. Elizabeth Huynh Elizabeth Huynh, DVM, is a diagnostic imaging resident and graduate student at University of Florida College of Veterinary Medicine. Her interests include ultrasonography, cross-sectional imaging, and nuclear medicine. She received her DVM from Ross University, finished her clinical year at Ohio State University, and completed a diagnostic imaging internship at Animal Specialty and Emergency Center in Los Angeles, California. Clifford R. Berry Clifford R. Berry, DVM, DACVR, is a professor of diagnostic imaging at University of Florida College of Veterinary Medicine. His research interests include cross-sectional imaging of the thorax, nuclear medicine, and biomedical applications of imaging. He received his DVM from University of Florida and completed a radiology residency at University of California–Davis. To see the references for this article, please visit tvpjournal.com .

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