JPC SYSTEMIC PATHOLOGY

DIGESTIVE SYSTEM

September 2024

D-M19

 

Signalment (JPC #4070541): 9-month-old, intact female Persian cat

 

HISTORY: This cat had a history of intermittent vomiting and failure to gain weight. Abdominal radiographs revealed a mass at the gastric pylorus. Exploratory laparotomy revealed a thickened gastric pylorus region characterized by a thickened wall and roughened mucosal surface.

 

HISTOPATHOLOGIC DESCRIPTION: Stomach, pylorus: Affecting 90% of this section, the wall of the pylorus is transmurally effaced by a mass-forming proliferation of innumerable large, plump fibroblasts arranged in long, interlacing streams and bundles intertwined with thick bands of branching, anastomosing, herringbone patterned, fibrous connective tissue of variable maturity ranging from loose and immature to dense and sclerotic. Admixed are abundant eosinophils and fewer macrophages and plasma cells. The overlying mucosa is extensively lost (ulcerated); within the remaining overlying and adjacent mucosa, gastric glands are decreased in number and often dilated, and the lamina propria is expanded by increased fibrous connective tissue and slightly increased numbers of lymphocytes, plasma cells, histiocytes, and eosinophils. The interface between the mucosa and the fibrous mass is composed of a large bed of granulation tissue which blends imperceptibly with the advancing front of the fibrous mass. At the edges of the fibrous mass, muscle fibers of the tunica muscularis are shrunken and hypereosinophilic (atrophy and necrosis) and surrounded by infiltrating fibrous connective tissue. Fibrous connective tissue infiltrates and expands perivascular tissue throughout much of the remaining muscular tunics. There are multiple lymphoid nodules within the serosa, and serosal vessels are often surrounded by edema and moderate numbers of eosinophils and lymphocytes.

 

MORPHOLOGIC DIAGNOSES: Stomach: Gastritis, eosinophilic and sclerosing, transmural, focally extensive, marked, with ulceration, Persian, feline.

 

CAUSE: Idiopathic

 

CONDITION: Feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF); scirrhous eosinophilic gastritis

 

GENERAL DISCUSSION:

• A feline-specific inflammatory condition affecting the gastrointestinal tract and associated lymph nodes, first described in 2009
• Primarily affects middle-aged cats

 

PATHOGENESIS:

• Not completely understood etiopathogenesis, suggestions include: 
  • Immunologic dysregulation triggered by one of multiple possible causes (parasitism, food allergy, dysbiosis, IBD, inherited genetic mutation leading to eosinophil dysregulation)
  • Presence of bacteria (gram positive cocci and gram negative bacilli embedded within sclerotic collagen of the lesion) have been associated with lesions; antibiotic therapy is not effective in treating the condition
  • Presence of fungi (Grau-Roma, J Comp Pathol, 2014)
  • Presence of Toxoplasma gondii
  • Presence of alimentary nematode Cylicospirura sp. in a free-ranging puma
  • No infectious etiology was reported in nearly half of cases in one report (Eckstrand, J Comp Pathol, 2013)
• Eosinophils elaborate major basic protein, TGF-β, IL-1B, and IL-6 (and more) à repetitive cycle of tissue destruction and fibrosis

 

TYPICAL CLINICAL FINDINGS:

• Digestive signs including persistent emesis, weight loss, and malnutrition
• An abdominal mass is frequently palpated or found on abdominal imaging
• Clinical pathology: Hyperproteinemia associated with hyperglobulinemia, hypoalbuminemia, +/- peripheral eosinophilia, mild peripheral neutrophilia

 

TYPICAL GROSS FINDINGS:

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Characteristic pattern of a network of coarse collagen trabeculae admixed with large spindle cells (myofibroblasts) mixed with predominantly eosinophilic inflammation
• Fibroplasia and inflammation extensively infiltrate the intestinal wall (may be transmural) and sometimes extend to regional lymph nodes
• Intestinal mucosa is frequently ulcerated

 

DIFFERENTIAL DIAGNOSIS:

• Gross appearance: Neoplasia (lymphoma, fibrosarcoma, adenocarcionoma), granuloma
• Histologic appearance: Neoplasia (fibrosarcoma, extraskeletal osteosarcoma [sclerotic collagen misinterpreted as osteoid], feline sclerosing mast cell tumor, lymphoma [sclerosing variant])
• Eosinophilic gastritis, 3 forms in dogs and cats:
  • Focal eosinophilic infiltrate in dogs and cats is sometimes associated with trapped intramural nematode larvae, due to antigenicity of nematode larval sheath, feces, and saliva; tissue reaction results in gastric epithelial cell hyperplasia resulting in polyp-like proliferation of antral mucosa; especially Toxocara canis (dogs)
  • Diffuse eosinophilic infiltrate is believed to be a hypersensitivity reaction to an unknown antigen, often with associated peripheral eosinophilia and intestinal eosinophilia; eosinophilic inflammation may become transmural with necrosis and scarring, and may be associated with visible hypertrophy of the tunica muscularis
  • Scirrhous eosinophilic gastritis of dogs and cats

 

COMPARATIVE PATHOLOGY:

• This condition is unique to felids; other than domestic cats, it has been recognized in pumas in association with Cylicospirura sp., although the puma lesions had fewer eosinophils
• Eosinophilic enteritis in equids: “Multisystemic epitheliotropic syndrome” associated with eosinophilic and granulomatous pancreatitis and eosinophilic dermatitis; it can cause a thickening of the mucosa (occasionally transmurally) within any segment of the gastrointestinal tract to include the esophagus; histologically will have a mixed inflammatory infiltration often with foci of eosinophils; these foci are occasionally surrounded by macrophages and multinucleated giant cells
  • It can occur as an enteritis separate from the multisystemic syndrome

 

REFERENCES:

1. Brosinski K, Burkhardt WA, Venzin C, Grest P. Diagnostic exercise: submucosal gastric masses in a cat. Vet. Pathol. 2013;50(2):350-353.
2. Craig LE, Hardam EE, Hertzke DM, et al. Feline Gastrointestinal eosinophilic sclerosing fibroplasia. Vet Pathol. 2009;46(1):63-70.
3. Eckstrand CD, Barr BC, Woods LW, Spangler T, Murphy B. Nematode-associated intramural alimentary nodules in pumas are histologically similar to gastrointestinal eosinophilic sclerosing fibroplasia of domestic cats. Comp. Pathol. 2013;148:405-409.
4. Grau-Roma L, Galindo-Cardiel I, Isidoro-Ayza M, Fernandez M, Majo N. A case of feline gastrointestinal eosinophilic sclerosing fibroplasia associated with phycomycetes. Comp. Pathol. 2014;151:318-321.
5. Spagnoli ST, Gelberg HB. Alimentary System and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:435,463. 
6. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:96.

Click the slide to view.

---