JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
September 2018
D-M02 (NP)

HISTORY (JPC #1902492): Tissue from a 4-year-old quarter horse with a 5-month history of diarrhea and progressive weight loss.

MICROSCOPIC DESCRIPTION: Small intestine:  Diffusely and circumferentially, the intestinal wall is expanded up to 8mm; the submucosa is expanded diffusely up to 2.5mm.  The submucosa and to a lesser extent the lamina propria are infiltrated and expanded by large numbers of lymphocytes, plasma cells, eosinophils, and fewer macrophages and neutrophils, admixed with eosinophilic cellular and karyorrhectic debris (necrosis), scattered hemorrhage, fibrin, and mild edema with ectatic submucosal lymphatic vessels.  This inflammation invades through and multifocally replaces the discontinuous muscularis mucosa.  Multifocally within the submucosa, dense, round to oval, 0.5-1.5mm, aggregates of brightly eosinophilic necrotic debris are surrounded by epithelioid macrophages, eosinophils, rare multinucleated giant cells, and concentric rings of collagen (eosinophilic granulomas).  The submucosa also contains increased small caliber blood vessels, reactive, haphazardly arrangedhypertrophied fibroblasts, surrounded by abundant edematous collagen (granulation tissue).  Multifocally, submucosal glands (Brunner’s glands) are mildly dilated and frequently filled with or obscured by nodular aggregates of degenerate eosinophils, necrotic cellular debris (necrosis), and abundant pale basophilic fibrillar material (mucin).  Within the lamina propria, lacteals are multifocally dilated and contain moderate numbers of lymphocytes with fewer eosinophils admixed with eosinophilic proteinaceous fluid (lymphangiectasia).  The mucosa is characterized by blunting and fusion of villi with erosion and rare ulceration of the mucosal epithelium. There are occasional crypt abscesses, and rare crypt herniation in foci of discontinuous muscularis mucosae.  The previously described inflammatory infiltrate extends multifocally into the tunica muscularis.  Multifocally, the serosa and outer layer of the tunica muscularis are expanded by increased clear space and dilated lymphatics (edema).  Within the intestinal lumen, there is an exudate composed of hemorrhage and fibrin admixed with sloughed epithelial cells, cellular debris and moderate numbers of eosinophils, lymphocytes, plasma cells, macrophages and few neutrophils.

MORPHOLOGIC DIAGNOSIS: Small intestine, mucosa and submucosa: Enteritis, eosinophilic and lymphohistiocytic, diffuse, severe, with eosinophilic granulomas, mucosal erosion/ulceration, granulation tissue and mild lymphangiectasia, quarter horse, equine.

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REFERENCES:

  1. Gelberg HB. Alimentary system and the peritoneum, omentum, mesentery, and peritoneal vacity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:390.
  2. Mauldin EA, Peters-Kennedy, J. Integumentary System. In: Maxie MG. ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier Saunders; 2015:695.
  3. 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. St. Louis, MO: Elsevier Saunders; 2015:96.


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