JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
September 2018
D-F04

Signalment (JPC 2841523):  Dog, age and breed not specified.

HISTORY:  This dog had a small intestinal mass.

HISTOPATHOLOGIC DESCRIPTION:  D-F04a:  Small intestine:  Affecting 60% of the section, transmurally replacing normal architecture, and markedly expanding the intestinal wall up to 1.2 cm in thickness, are multiple coalescing granulomas centered on cores of abundant necrotic debris admixed with numerous degenerate eosinophils and neutrophils, and small amounts of fibrin and hemorrhage.  Necrotic cores contain low numbers of negatively staining and poorly-discernible hyphae, and are surrounded by a band of numerous macrophages, including epithelioid macrophages, and fewer multinucleated giant cells (Langhans and foreign body type), admixed with eosinophils and neutrophils.  These are further surrounded by numerous haphazardly arranged hypertrophied fibroblasts and anundant collagen (fibrous connective tissue) admixed with previously described inflammatory cells.  There are multifocal areas of degranulating eosinophils surrounding individualized collagen bundles (collagenolysis). Collagen bundles and smooth muscle fibers throughout the tunica muscularis are replaced by plump fibroblasts and widely separated by the degranulated eosinophils, previously described inflammatory infiltrate, edema, and few small areas of hemorrhage. There are multifocal areas of smooth muscle fiber loss or necrosis, and the tunica muscularis is replaced by abundant fibrosis. In less affected areas there is expansion of the submucosa and lamina propria by infiltrates of epitheloid macrophages, neutrophils, eosinophils, increased clear space and ectatic lymphatics (inflammation and edema), fusion and blunting of the villi, and rare granulomas.  There is focally extensive compression of the intestinal lumen and effacement of mucosal architecture by the aforementioned inflammation and fibrosis.

D-F04b:  GMS:  Scattered throughout the tissue, but primarily within the center of granulomas, are small to moderate numbers of GMS-positive, 4-8 um wide hyphae with nonparallel walls, non-dichotomous acute and right angle branching, and rare septations.

MORPHOLOGIC DIAGNOSIS:  Small intestine:  Enteritis, granulomatous, eosinophilic, and fibrosing, focally extensive, transmural, marked, with rare GMS-positive hyphae, canine.

ETIOLOGIC DIAGNOSIS:  Enteric pythiosis

CAUSE:  Pythium insidiosum

CONDITION:  Pythiosis, oomycosis

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. do Carmo PM, Protella RA, Silva TR, Oliveira-Filho JC, Riet-Correa F. Cutaneous pythiosis in a goat. J Comp Pathol. 2015; 152(2-3):103-105.
  2. Hargis AM, Myers, S. The Integument. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1083.
  3. Maia, LA, Olinda RG, et al. Cutaneou pythiosis in a donkey (Equus asinus) in Brazil. J Vet Diagn Invest. 2016; 28(4):436-439.
  4. Mauldin, EA, Peters-Kennedy, J. Integumentary System. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier Ltd; 2016:657-659.
  5. Souto EPF, Olinda RG, et al. Pythiosis in the nasal cavity of horses. J Comp Pathol. 2016; 155(2-3):126-129.
  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. St. Louis, MO: Elsevier Ltd; 2016:177-180.


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