JPC SYSTEMIC PATHOLOGY

DIGESTIVE SYSTEM

September 2024

D-M14 (NP)

 

Signalment (JPC #2558677): 9-month old female beagle

 

HISTORY: Incidental necropsy finding in a beagle used in a toxicology study.

 

HISTOPATHOLOGIC DESCRIPTION: Jejunum: Multifocally replacing intestinal mucosa are several well-demarcated foci, up to 1.5 mm wide, of gastric mucosa composed of tightly packed tubular glands lined by an admixture of cuboidal cells with either basally positioned nuclei and apical, lightly eosinophilic, foamy cytoplasm (chief cells) or with more centralized, round nuclei and abundant eosinophilic, granular cytoplasm (parietal cells). Diffusely, remaining jejunal villi and crypts are lined by markedly increased numbers of goblet cells (goblet cell hyperplasia).

 

MORPHOLOGIC DIAGNOSIS: Jejunum: Heterotopic gastric fundic mucosa, multifocal, segmental, with diffuse goblet cell hyperplasia, beagle, canine.

 

CONDITION: Gastric heterotopy (choristoma)

 

GENERAL DISCUSSION:

• Extremely rare in animals; has been reported in the dog and cat

• A survey of 365 beagle dogs found 4.1% affected, with higher incidence in males

• Choristoma: Mature tissue in an ectopic location

• Most commonly involves ectopic gastric or pancreatic tissue in the intestines, with one report of intestinal choristoma in the subcutis

• It was the site of development of a gastric adenocarcinoma in one beagle

 

PATHOGENESIS:

• Congenital rest of normal gastric mucosa that can occur at any level of the gastrointestinal tract

• The site in one report coincided with the usual site of Meckel’s diverticulum

 

TYPICAL CLINICAL FINDINGS: 

 

TYPICAL GROSS FINDINGS: 

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Islets of histologically normal, well circumscribed gastric mucosa (surface mucus cells, chief cells, parietal cells and mucus neck cells of the stomach) replacing small intestinal mucosa; adjacent small intestine is normal
• Submucosal and muscular layers are a continuation of the corresponding layers of the small intestine
• Goblet cell hyperplasia in adjacent mucosa may be a protective response to gastric acid secretion by the heterotopic tissue

 

ADDITIONAL DIAGNOSTIC TESTS: 

 

DIFFERENTIAL DIAGNOSIS:

Intestinal Masses: 

• Intestinal neoplasms
• Hyperplastic polyps
• Inflammation (e.g. pythiosis)

 

COMPARATIVE PATHOLOGY:

• Two Siamese cats with heterotopic gastric mucosa within the mucosa of dilated esophagi have been reported
• Occurs in esophagus, thoracic and abdominal cysts, bile duct, gallbladder, intestinal tract and intestinal diverticula in humans

 

REFERENCES:

1. World Health Organization International Histological Classification of Tumors of Domestic Animals. Vol X. Second Series. Armed Forces Institute of Pathology; 2003:108-109.
2. Bishop LM, Kelly DF, and Pearson H. Megaloesophagus and associated gastric heterotopia in the cat. Vet Pathol. 1979;16:444-449. 
3. Brannick EM, Newkirk KM, Schaefer MW. Neoplasia and Tumor Biology. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:344-345.
4. Iwata H, Arai C, Koike Y, et al. Heterotopic gastric mucosa of the small intestine in laboratory beagle dogs. Toxicol Pathol. 1990;18:373-379.
5. Husain AN, Koo SC. Diseases of infancy and childhood. In: Kumar V, Abbas AK, Aster JC, eds. Robbins and Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Saunders Elsevier; 2021: 475. 
6. Kumar V, Abbas AK, Aster JC. The gastrointestinal tract. In: Robbins and Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Saunders Elsevier; 2021: 755. 
7. Panigrahi D, Johnson AN, Wosu NJ. Adenocarcinoma arising from gastric heterotopia in the jejunal mucosa of a beagle dog. Vet Pathol. 1994;31:278-80.

 

 

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