JPC SYSTEMIC PATHOLOGY
DIGESTIVE SYSTEM
November 2018
D-V22

SIGNALMENT (JPC #1956094):  5-month-old lamb

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Tongue:  Multifocally, the hyperplastic epithelium is expanded up to 500 um and contains numerous various sized pustules with many degenerate neutrophils, fewer macrophages, lymphocytes, and plasma cells admixed with hemorrhage, fibrin and edema.  Multifocally, the pustules are ruptured and the superficial epithelium is eroded and covered in a disorganized coagulum of karyorrhectic and cellular necrotic debris and degenerate neutrophils.  Adjacent keratinocytes are swollen with abundant pale eosinophilic to clear vacuolated cytoplasm (hydropic degeneration) and multifocally contain 5-10 um diameter, round, eosinophilic intracytoplasmic viral inclusion bodies.  Multifocally, individual keratinocytes are shrunken with bright eosinophilic cytoplasm and karyorrhexis, karyolysis, or nuclear pyknosis (necrosis). Hemorrhage, fibrin, edema and low to moderate numbers of neutrophils, lymphocytes and macrophages moderately expand the adjacent subepithelial connective tissue and separate, surround, and expand the perimysium and endomysium of underlying skeletal muscle bundles and fibers, respectively. There is a moderate increase in subepithelial, small caliber vessels which are frequently lined by hypertrophied, reactive endothelium.  Multifocally, individual myocytes are swollen with vacuolated sarcoplasm (degeneration) or shrunken with bright eosinophilic cytoplasm, disorganization of myofibrils, loss of cross striations and absent or pyknotic nuclei (necrosis).  Multifocally expanding skeletal myofibers are thin-walled protozoal cysts up to 80 um in diameter containing numerous crescentic basophilic bradyzoites (sarcocysts).  On the epithelial surface and within the stratum corneum, there are multiple colonies of 1 x 3 um filamentous bacilli.

 MORPHOLOGIC DIAGNOSIS: 

  1. Tongue:  Glossitis, proliferative and necrotizing, multifocal, moderate, with hydropic degeneration, intraepithelial pustules, and epithelial eosinophilic intracytoplasmic viral inclusion bodies, breed not specified, ovine.
  2. Tongue, skeletal muscle: Intramuscular protozoal cysts, multiple, etiology consistent with Sarcocystis sp.

ETIOLOGY:  Ovine parapoxvirus (family Poxviridae, genus Parapoxvirus)

ETIOLOGIC DIAGNOSIS:  Ovine parapoxviral glossitis and glossal sarcocystosis

CONDITION:  Contagious ecthyma (CE)

SYNONYMS:  Orf (human condition), contagious pustular dermatitis (stomatitis), sore mouth, scabby mouth

GENERAL DISCUSSION: 

PATHOGENESIS: 

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:              

REFERENCES: 

  1. Gelberg HB. Alimentary system and the peritoneum, omentum, mesentery, and peritoneal cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:391-392.
  2. Hampton AL, Dyson MC, Bergin IL. Pathology in practice. 3-week-old female Suffolk lamb with a large perianal mass. J Am Vet Med Assoc. 2012;240(11):1293-1295.
  3. Hargis AM, Myers, S. The Integument. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1068-1069,1124-1125.
  4. MacLachlan NJ, Dubovi EJ. Fenner’s Veterinary Virology. 4th ed. London, UK: Academic Press; 2017: 158-160,171.
  5. 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; 2016:615-619.
  6. Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, eds. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier; 2016: 140.
  7. Zachary JF. Mechanisms of microbial infections. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:202-203.


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