JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

November 2016

I-V06

 

SIGNALMENT: Mouse

HISTORY:  This mouse died after a short period of malaise.  Many cutaneous lesions were present.

HISTOPATHOLOGIC DESCRIPTION:  Haired skin:  The epidermis is diffusely ulcerated and replaced by an eosinophilic necrotic coagulum composed of numerous degenerate neutrophils, karyorrhectic debris and multifocal colonies of mixed bacteria.  This serocellular crust extends into the underlying dermis and disrupts normal dermal and adnexal architecture.  Multifocally follicular epithelial cells exhibit ballooning degeneration and both follicular epithelial cells and sebocytes occasionally contain one to multiple round to oval, eosinophilic, intracytoplasmic viral inclusion bodies up to 15 um in diameter (Marchal bodies).  There is marked perifollicular, follicular and dermal inflammation, characterized by numerous neutrophils, lymphocytes and plasma cells with fewer macrophages, and mast cells, which extend into the underlying panniculus and often separate and surround myofibers, adipocytes and nerve bundles.  There is multifocal, marked edema within the dermis and panniculus, with diffuse congestion and scattered hemorrhage.  Myofibers multifocally undergo degeneration and necrosis.

MORPHOLOGIC DIAGNOSIS:  Haired skin:  Dermatitis, necrotizing, subacute, diffuse, severe, with follicular epithelial ballooning degeneration, neutrophilic and lymphoplasmacytic folliculitis and panniculitis, and follicular epithelial and sebocytic eosinophilic intracytoplasmic viral inclusion bodies, strain unspecified mouse, rodent.

ETIOLOGIC DIAGNOSIS:  Orthopoxviral dermatitis

CAUSE:  Ectromelia virus (murine orthopoxvirus)    

CONDITION:  Mousepox

CONDITION SYNONYM:  Ectromelia

GENERAL DISCUSSION: 

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS: 

TYPICAL GROSS FINDINGS:

TYPICAL MICROSCOPIC FINDINGS: 

ULTRASTRUCTURE: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS: 

Cutaneous lesions:

Hepatic necrosis:

 COMPARATIVE PATHOLOGY:

Genus Orthopox:

Genus Parapox:

 REFERENCES: 

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents & Rabbits, 4th ed. Ames, IA: Blackwell Publishing; 2016: 21-23.
  2. Chapman JL, Nichols DK, Martinez MJ, Raymond JW. Animal models of Orthopoxvirus Vet Pathol. 2010;47(5):852-870.
  3. De Sant’Ana FJ, Leal FA, Rabelo RE, et al. Coinfection by vaccinia virus and an Orf virus-like parapoxvirus in an outbreak of vesicular disease in dairy cows in midwestern Brazil. J Vet Diagn Invest. 2013;25(2):267-272.
  4. MacLachlan NJ, Dubovi EJ. Fenner’s Veterinary Virology, 4th ed. London, UK: Elsevier; 2011: 151-165.
  5. Origgi FC, Sattler U, Pilo P, Waldvogel AS. Fatal combined infection with canine distemper virus and orthopoxvirus in a group of Asian marmots (Marmota caudata). Vet Pathol. 2013;50(5):914-920.
  6. Miller WH, Griffin CE, Campbell KL. Viral, rickettsial, and protozoal skin diseases. In: Miller WH, Griffin CE, Campbell KL eds. Small Animal Dermatology, 7th ed. Philadelphia, PA: WB Saunders Company; 2013: 344-345.
  7. Wiener DJ, Welle MM, Origgi FC. Cutaneous lesions associated with dual infection caused by canine distemper virus and orthopoxvirus in a domestic cat. Vet Dermatol. 2013;24(5):543-e130.
  8. Mauldin EA, Peters-Kennedy J. Integumentary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, Vol 1. 6th ed. Philidelphia, PA: Elsevier Saunders; 2015: 616.


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