JPC SYSTEMIC PATHOLOGY

INTEGUMENT SYSTEM

October 2016

I-P03

 

Signalment (JPC # 1957368):  Adult horse, age and breed unspecified

HISTORY:  Horse with pruritic nodules ventral to medial canthus of each eye

MICROSCOPIC DESCRIPTION:  Haired skin and subcutis:  Markedly infiltrating the dermis and subcutis and extending into the panniculus carnosus, there are multifocal to coalescing eosinophilic granulomas up to 2 mm in diameter which contain rare cross-sections of nematode larvae.  The granulomas frequently contain a core of eosinophilic necrotic debris mixed with many degenerate eosinophils surrounded by epithelioid macrophages and occasional multinucleated giant cells (foreign body type), further bounded by a layer of fibroblasts and fibrosis.  Rarely, granulomas contain up to 60 um diameter nematode larvae with a smooth, 1-2 um thick cuticle, coelomyarian-polymyarian musculature, prominent lateral chords, and a digestive tract lined by cuboidal, uninucleate cells.  Diffusely, in the surrounding subcutis and dermis, there are numerous eosinophils with fewer lymphocytes and plasma cells, admixed with variably sized small caliber blood vessels that are lined by reactive endothelial cells and surrounded by hypertrophied fibroblasts (granulation tissue), all of which separates and surrounds collagen bundles, muscle fibers and adnexa.  Numerous collagen fibers are shrunken, hypereosinophilic, fragmented or hyalinized and occasionally surrounded by degranulated eosinophils (flame figures).  Multifocally myocytes are atrophied, have vacuolated sarcoplasm (degeneration) or have hypereosinophilic sarcoplasm with pyknosis and loss of cross striations (necrosis).  The epidermis is mildly hyperplastic and there is a focally extensive ulcer with replacement by many degenerate inflammatory cells, fibrin, edema and necrotic debris.  . 

MORPHOLOGIC DIAGNOSIS:  Haired skin and subcutis:  Eosinophilic granulomas, multiple, with severe diffuse eosinophilic dermatitis and panniculitis, ulceration, collagen flame figures, and rare spirurid nematode larvae, breed unspecified, equine.

ETIOLOGY:  Habronema muscae, Habronema majus, Draschia megastoma

ETIOLOGIC DIAGNOSIS:  Cutaneous habronemiasis

CONDITION:  Summer sores

CONDITION SYNONYMS:  Granular dermatitis, bursatti, esponja

GENERAL

LIFECYCLE

PATHOGENESIS

 TYPICAL CLINICAL FINDINGS

TYPICAL GROSS FINDINGS

TYPICAL MICROSCOPIC FINDINGS

ADDITIONAL DIAGNOSTIC TESTS

DIFFERENTIAL DIAGNOSIS

For gross findings:

For microscopic lesions (eosinophilic nodular dermatitis):

COMPARATIVE PATHOLOGY:

REFERENCES

  1. Bowman DD. Georgis’ Parasitology for Veterinarians. 10th ed. St. Louis, MO: Elsevier Saunders; 2014: 211-212.
  2. Foster RA. Male reproductive system. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 1217-1218.
  3. Hargis AM, Myers S. The integument. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 1120.
  4. Labelle P. The eye. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 1310.
  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: 685-686.
  6. Myers DA, et al. Cutaneous periocular Habronema infection in a dromedary camel (Camelus dromedarius). Vet Dermatol. 2010;21(5):527-530.
  7. Pusterla N, Watson JL, Wilson WD, Affolter VK, Spier SJ. Cutaneous and ocular habronemiasis in horses: 63 cases (1988-2002). J Am Vet Med Assoc. 2003;222:978-982.
  8. Scott DW, Miller WH. Parasitic diseases. In: Equine Dermatology. 2nd ed. Maryland Heights, MO: Elsevier Saunders; 2011: 239-242.
  9. 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; 2016: 209-210.


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