ISSN 2398-2969      

Skin: pigmented viral plaque

icanis
Contributor(s):

David Godfrey

John Munday

Synonym(s): Pigmented plaque, canine epidermodysplasia verruciformis


Introduction

  • Cause: multiple canine papillomavirus types (but not types 1, 2, and 6).
  • Signs: multiple 1cm diameter darkly pigmented plaques on the ventrum of the dog.
  • Pugs and minature schnauzers appear predisposed, but plaques can occur in any breed.
  • Diagnosis: histopathology required for definitive diagnosis.
  • Treatment: surgical excision if evidence of neoplastic transformation is observed.
  • Prognosis: the majority of plaques develop and then stabilize causing no significant disease. However, a small proportion of plaques progress toin situcarcinomas and careful observation is recommended. It is possible sunlight could influence neoplastic progression of a plaque toin situcarcinoma.

Pathogenesis

Etiology

  • Multiple different canine papillomavirus types have been associated with pigmented plaques.
  • Plaques are not caused by the same papillomavirus types that cause cutaneous Skin: cutaneous papilloma or oral papillomas Mouth: viral papilloma.

Predisposing factors

General
  • It appears most dogs are asymptomatically infected with papillomaviruses that could potentially cause plaques.
  • Therefore plaque development is dependent on host factors rather than the presence of the virus.
  • Immunosuppression (corticosteroid therapy, Cushing's disease Hyperadrenocorticism , hypothyroidism Hypothyroidism ) has been associated with the development of plaques in some cases.
  • Pugs and miniature schnauzers appear to have a genetic inability to control cutaneous papillomavirus infection and so are predisposed to plaques.
  • Plaques can develop in dogs of any breed even in the absence of identifiable immunosuppressive disease.

Pathophysiology

  • Papillomaviruses infect basal cells in the epidermis.
  • Infection is maintained, but in most dogs, no clinical evidence of infection is present.
  • Rarely, host factors in a dog will allow greater viral replication and the development of plaques.
  • Most plaques remain stable, but plaques can progress toin situcarcinoma.
  • Ifin situcarcinomas are not surgically excised, they have the potential to progress to invasive squamous cell carcinomas Skin: squamous cell carcinoma.
  • It is possible that exposure to sunlight increases the chance of neoplastic transformation.

Timecourse

  • Infection by the causative papillomaviruses probably occurs in the first few days of life.
  • Plaques typically are first observed in dogs as young adults.
  • Plaques are generally stable over a long time period and many dogs have plaques throughout life without any disease progression.
  • Progression of a plaque to anin situcarcinoma can occur rapidly or over a long time period and is impossible to predict. Likewise, progression fromin situto invasive carcinoma cannot be accurately predicted although the chance of progression probably increases with time.

Epidemiology

  • It is currently thought that infection by the causative papillomaviruses is common, but disease is rare.
  • This illustrates the importance of host factors in disease development.

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.
  • Lange C E, Favrot C (2011) Canine papillomaviruses. Vet Clin North Am Small Anim Pract 41 (6), 1183-1195 PubMed.
  • Munday J S, O'Connor K I, Smits B (2011) Development of multiple pigmented viral plaques and squamous cell carcinomas in a dog infected by a novel papillomavirus. Vet Dermatol 22 (1), 104-110 PubMed.
  • Munday J S, Kiupel M (2010) Papillomavirus-associated cutaneous neoplasia in mammals. Vet Pathol 47 (2), 254-264 PubMed.
  • Lange CE, Tobler K, Ackermann M et al (2009) Three novel canine papillomaviruses support taxonomic clade formation. J Gen Virol 90 (Pt 11), 2615-2621 PubMed.
  • Lange CE, Tobler K, Favrot C et al (2009) Detection of antibodies against epidermodysplasia verruciformis-associated canine papillomavirus 3 in sera of dogs from Europe and Africa by enzyme-linked immunosorbent assay. Clin Vaccine Immunol 16 (1), 66-72 PubMed.
  • Tobler K, Lange C, Carlotti D N et al (2008) Detection of a novel papillomavirus in pigmented plaques of four pugs. Vet Dermatol 19 (1), 21-25 PubMed.
  • Tobler K, Favrot C, Nespeca G et al (2006) Detection of the prototype of a potential novel genus in the family Papillomaviridae in association with canine epidermodysplasia verruciformis. J Gen Virol 87 (Pt 12), 3551-3557 PubMed.
  • Narama I, Kobayashi Y, Yamagami T et al (2005) Pigmented cutaneous papillomatosis (pigmented epidermal nevus) in three pug dogs; histopathology, electron microscopy and analysis of viral DNA by the polymerase chain reaction. J Comp Pathol 132 (2-3), 132-138 PubMed.
  • Tanabe C, Kano R, Nagata M et al (2000) Molecular characteristics of cutaneous papillomavirus from the canine pigmented epidermal nevus. J Vet Med Sci 62 (11), 1189-1192 PubMed.
  • Le Net J L, Orth G, Sundberg J P et al (1997) Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog. Vet Pathol 34 (1), 8-14 PubMed.

Other sources of information

  • Gross T L, Ihrke P J, Walder E J (2005)Skin diseases of the dog and cat: clinical and histopathologic diagnosis.2nd edn. Blackwell Science, Oxford, United Kingdom.

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