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16-year-old, male castrated Maine Coon

  • Presented for an initial internal medicine consultation for further evaluation of previously diagnosed chronic enteropathy, chronic constipation, IRIS Stage II chronic kidney disease, and newly elevated liver enzymes (mild elevation in ALT and ALP).
  • Clinical signs at presentation included mild weight loss over the past year, polyuria, and intermittent hyporexia.
  • Ultrasound performed 1.5 years prior showed a mild segmental enteropathy, mild to moderate colonic distension, and a mild diffuse hepatopathy.

View the carousel of still images above and the video of the duodenum below…


  • Hyperechoic, somewhat spongiform hyperechoic nodule extends from a single vascular marking in the mucosa of the duodenum, close to the pyloroduodenal junction.
  • The nodule measures 1.2 cm diameter and has a few very small anechoic cysts in it
  • The nodule remains in the same position as the duodenum contracts
  • The duodenum is otherwise empty; the stomach is empty
  • Wall layering of the duodenum is maintained

Other findings (not included in the images)

  • Diffusely hyperechoic and mildly enlarged liver with multifocal poorly margined hypooechoic nodules that do not deform the liver capsule
  • Normal GI tract otherwise
  • The location and architecture of the nodule is most consistent with a non-obstructive proximal duodenal polyp
  • The hepatopathy may be related to vacuolar hepatopathy and nodular hyperplasia. ¬†Hepatitis and liver neoplasia cannot be ruled out
  • Negative for diffuse enteropathy

Gastrointestinal polyps are defined as circumscribed lesions protruding from the mucosal surface.1 This is a descriptive term, and the nature of the lesion is further classified histologically. Benign adenomatous polyps contain epithelial cells arranged in tubules with a fibrovascular core resembling or extending from the lamina propria, with varying degrees of inflammation.2,3 Ultrasonographically, pyloroduodenal polyps are described as moderately echogenic and homogenous nodules filling most of the proximal duodenal or pyloroduodenal lumen without regional lymphadenopathy.2

Polyps of the digestive tract are infrequently reported in cats, though they may be under-reported as patients are frequently asymptomatic, and lesions can be found incidentally. When clinical signs are present, they most commonly include vomiting, anorexia, and lethargy.2,4 Pyloroduodenal polyps can be ulcerated and result in clinically significant gastrointestinal bleeding and anemia, cause partial gastrointestinal obstruction, and have the potential for bile flow impairment.1,2

In this case, the pyloroduodenal polyp was thought to be an incidental finding, and the clinicopathologic abnormalities were attributed to progression of the hepatopathy.  

Pyloroduodenal polyps can be missed on ultrasonographic examination as their echotexture can resemble normal ingesta. In a recent study, 2/6 pyloroduodenal polyps were missed during initial ultrasound examination and were subsequently identified on retrospective review of still images and/or video clips.2 Pyloroduodenal nodules can also be mistaken for malignancy. These lesions can be safely excised surgically or via endoscopic polypectomy, and if benign, carry an excellent prognosis.1,2,4


  1. Gualtieri M and Monzeglio MG. Gastrointestinal polyps in small animals. Eur J Comp Gastroenterol 1996; 1:5-11.
  2. Duare E, Jania R, Jennings S, et al. Ultrasonographic and clinicopathological features of pyloroduodenal adenomatous polyps in cats. J Feline Med Surg 2017; 19(2): 141-145.
  3. Kehl A, Torner K, Jordan A, et al. Pathological findings in gastrointestinal neoplasms and polyps in 860 cats and a pilot study on miRNA analyses. Vet Sci 2022; 9(9): 477.
  4. MacDonald JM, Mullen HS, and Moroff SD. Adenomatous polyps of the duodenum in cats: 18 cases (1985-1990). J Am Vet Med Assoc 1993; 202: 647-651.