JPC SYSTEMIC PATHOLOGY

INTEGUMENTARY SYSTEM

November 2016

I-P13 (NP)

 

Signalment (JPC 21474-16):  7-year-old German shepherd dog

HISTORY:  A draining skin lesion from a dog from South Vietnam

HISTOPATHOLOGIC DESCRIPTION:  Fibroadipose tissue:  Diffusely, the tissue is replaced by abundant eosinophilic cellular and karyorrhectic debris (necrosis), admixed with abundant viable and degenerate neutrophils, eosinophils, fewer plasma cells, lymphocytes and macrophages.  Multifocally there is profuse hemorrhage separating and surrounding collagen fibers and adipocytes and frequently there are large cross and tangential sections of arthropod larvae up to 8x4 mm. The arthropod larvae have a 40 to 50 um chitinous cuticle with short, yellow spines, striated skeletal muscle, a hemocoelom, chitinized tracheal rings, a large tortuous digestive tract, and gonads (dipteran).  Collagen bundles are frequently separated by either clear space or a pale eosinophilic, beaded to fibrillar material (fibrin) with multifocal ectatic lymphatics (edema).  There are large numbers of reactive fibroblasts admixed with numerous small caliber blood vessels, hemorrhage, and edema (granulation tissue).  Multifocally, vessels contain fibrin thrombi.  Within necrotic areas surrounding the arthropod larvae, there are high numbers of previously described inflammatory cells admixed with aggregated colonies of 1um basophilic cocci.  

MORPHOLOGIC DIAGNOSIS:  Fibroadipose tissue:  Cellulitis, suppurative and eosinophilic, chronic, diffuse, severe, with dipteran larvae, German shepherd dog, canine.

ETIOLOGIC DIAGNOSIS:  Cutaneous chrysomyiasis

ETIOLOGY:  Chrysomya bezziana (Asian and African screw worm)

CONDITION:  Myiasis

GENERAL DISCUSSION: 

PATHOGENESIS:

TYPICAL GROSS OBSERVATIONS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTICS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY

REFERENCES:

  1. Bowman DD. Arthropods. In: Georgis’ Parasitology for Veterinarians. 10th ed. Philadelphia, PA: WB Saunders; 2014: 26-29.
  2. Buisch WW, Hyde JL, Mebus CA. Screwworm myiasis. In: Foreign Animal Diseases. Richmond, VA: Carter Printing Company; 1992: 333-342.
  3. Christen JA, Skoda SR, Heng-Moss TM, Lee DJ, Foster JE. Sequence-characterized amplified regions that differentiate New World screwworms from other potential wound-inhabiting flies.  J Vet Diagn Invest.  2015;27(1):25-30.
  4. Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissue. Washington, DC: Armed Forces Institute of Pathology; 1999: 56-61.
  5. Mauldin EA, Peters-Kennedy J. Integument system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. New York, NY: Elsevier Limited; 2016: 669-670.
  6. Scott DW. Parasitic diseases. In: Large Animal Dermatology. Philadelphia, PA: WB Saunders; 1988: 245-251.
  7. Scott DW, Miller WH, Griffin CE. Parasitic skin diseases. In: Muller and Kirk’s Small Animal Dermatology. 6th ed. Philadelphia, PA: WB Saunders; 2001: 500-505.
  8. Urquhart GM, Armour J, Duncan JL, Dunn AM, Jennings FW. Veterinary Parasitology. 2nd ed. London, England: Blackwell Science; 1996: 141-169.
  9. Williams KJ, Summers BA, De Lahunta A. Cerebrospinal cuterebriasis in cats and its association with feline ischemic encephalopathy. Vet Pathol. 1998; 35:330-343.


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