title: Clinicopathological findings of canine seborrhoeic keratosis with comparison to pigmented viral plaques.
abstract: BACKGROUND
  Seborrhoeic keratoses (SKs) are common benign epidermal neoplasms in humans and are rarely diagnosed in the dog. These circumscribed, raised, variably pigmented plaques arise in middle aged to older humans, with a focal or multicentric distribution; although common, the underlying cause of these lesions is not known. Although less common in the dog, the lesions are similar and have features that overlap with papillomavirus-associated pigmented viral plaques.
  
  
  OBJECTIVE
  Seborrhoeic keratoses in the dog are negative for canine papillomavirus.
  
  
  METHODS
  Eleven cases of SK from a 12 year period were reviewed.
  
  
  METHODS
  This was a retrospective study of the histopathological findings and case histories. Complete clinical records following collection of the skin biopsy were available in five of 11 cases. Immunohistochemistry was performed for all cases; PCR analysis was carried out for papillomavirus in six cases.
  
  
  RESULTS
  Histologically, SKs had an exophytic to mildly endophytic epidermal proliferation, creating a papillomatous to acanthotic, hyperkeratotic, frequently pigmented plaque. There was an absence of hypergranulosis or viral cytopathic effect; PCRs for canine papillomavirus within the formalin-fixed paraffin-embedded skin biopsies were negative. No breed, sex or site predilection was recognized. The mean age at biopsy of the lesions was 8.8 years (range 5-14 years).
  
  
  CONCLUSIONS
  Histopathological features and negative papillomavirus status distinguish SK as an important differential diagnosis for pigmented viral plaques in dogs.
authors.affiliation: Department of Pathobiology, Anatomic Pathology, University of Pennsylvania, School of Veterinary Medicine, 3900 Delancey Street, MJR VHUP 4037, Philadelphia, PA 19104-6051, USA. cbradle2@vet.upenn.edu
authors.forename: Charles W
authors.initials: CW
authors.lastname: Bradley
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Luff
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Mauldin
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D017492:Keratosis, Seborrheic / Q000473:pathology / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies; D017193:Skin Diseases, Viral / Q000473:pathology / Q000662:veterinary*