ISSN 2398-2977      

Eosinophilic granuloma

pequis

Synonym(s): Nodular necrobiosis, eosinophilic granuloma with collagen degeneration, acute collagen necrosis, nodular collagenolytic granuloma


Introduction

  • The most common, non-neoplastic, nodular skin disease of the horse.
  • Cause: uncertain. Possibly hypersensitivity reactions.
  • Signs: isolated individual papules or groups or chains of papules or nodules predominately over the back, neck and withers. Can be extensive and much larger areas involved.
  • Diagnosis: history, physical examination, biopsy.
  • Treatment: benign neglect (some resolve or shrink). Surgical excision or intralesional corticosteroids.
  • Prognosis: good.

Pathogenesis

Etiology

  • Insect bite reactions   Insect hypersensitivity   have been suggested. This hypothesis is further supported by the fact that histopathological changes are similar to the ones observed in cats and horses with other hypersensitivity reactions. 
  • Trauma has been suggested as an etiology for lesions occurring in the saddle region.
  • Some lesions appear post-clipping.
  • Silicone coated needles have been reported anecdotally to cause it.
  • No evidence of auto-immune condition   Skin: atopy  .

Predisposing factors

General
  • Most cases develop in the spring/summer but signs may be seen some weeks after onset.
  • Successive waves/crops of lesions may develop in individual horses.

Pathophysiology

  • The pathogenesis is unknown, although probably involves some form of hypersensitivity reaction.
  • Similar lesions reported in dogs, cats, horses and man.
  • Trauma has been suggested as an etiology for lesions occurring in the saddle region.
  • Unknown, although horses with other hypersensitivities such asCulicoideshypersensitivity   Insect hypersensitivity  , atopic dermatitis   Skin: atopy  , onchocerciasis   Skin: onchocerciasis   and possibly food hypersensitivity; cats with atopic dermatitis, mosquito, flea or food hypersensitivities, have histologically identical lesions.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Barrelet A, Foote A & Littlewood J D (2010) Common equine skin tumours. UK Vet 15 (6), 9-17 VetMedResource.
  • Uhlhorn M, Hurst M & Demmers S (2006) Disseminated eosinophilic pulmonary granulomas in a pony. Equine Vet Educ 18 (4), 178-181 VetMedResource.
  • Pilsworth R C & Knottenbelt D C (2005)Nodular collagen necrosis (collagenolytic granuloma).Equine Vet Educ 17 (5), 228-229 VetMedResource.
  • Valentine B A (2005) Equine cutaneous non-neoplastic nodular and proliferative lesions in the Pacific NorthwestVet Derm 16 (6), 425-428 PubMed.
  • Lloyd D et al (2000) Stannards illustrated equine dermatology notes: nodular diseases. Vet Derm 11, 179-186 VetMedResource.
  • Slovis N M (1999) Injection site eosinophilic granulomas and collagenolysis in 3 horses. J Vet Intern Med 13 (6), 606-612 PubMed.
  • Mathison P T (1995) Eosinophilic nodular dermatoses. Vet Clin North Am Equine PractDerm, 75-77 PubMed.

Other sources of information

  • Scott D W (1988) Large Animal Dermatology. W B Saunders. USA. ISBN: 0721685536.

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