Viral skin infections - Pathology

()Map INTEGUMENTARY SYSTEM (Map) SKIN INFECTIOUS

Herpesviruses

• Cutaneous lesions may develop with nondermatotropic viruses:
  • Infectious bovine rhinotracheitis (bovine herpes virus - 1)
  • Equine coital exanthema (equine herpes virus - 3)
  • Feline herpes virus -1 (rarely)
• Dermatotropic viruses:

Bovine Herpesvirus 2

• May be latent and reappear at times of stress
• Grossly:
  • Vesicles, ulcers, crusts
• Microscopically:
  • Intraepidermal vesicle
  • Epidermal cell degeneration
  • Acantholysis
  • Syncytial cells may form
  • Intracellular inclusion bodies may be found at edges of ulcers
  • Rapid necrosis

Poxviruses

• Lesion development:
  • Due to viral invasion of epithelium
  • Vascular injury -> ischaemic necrosis
  • Stimulation of host DNA -> hyperplastic nodules
• Cutaneous lesions:
  • Macule -> papule -> vesicle -> umbilicated pustule -> crust -> scar

Contagious ecthyma

Contagious ecthyma (Courtesy of Bristol BioMed Image Archive)

• Also called contagious pustular dermatitis, orf, sore mouth
• Caused by a parapox virus
• Affects mainly young sheep, less commonly cattle, humans, dogs
• Starts in abrasions around mouth commisures and spreads to lips, oral mucosa, eyelids and feet
• May also transfer to teats of the mother of an affected lamb
• Lesions typical of poxvirus but very brief vesicle stage
• Most obvious is the proliferative pustular stage

Other viruses

• Cutaneous lesion are seen with:
  • Picornaviridae
    • Foot-and-mouth disease
    • Swine vesicular disease
  • Rhabdoviridae
    • Vesicular stomatitis
  • Caliciviridae
    • Vesicular exanthema
  • Retroviridae
    • Feline leukemia virus
      • Cutaneous horns on foot pads
      • Epidermal and follicular epithelial hyperplasia, epidermal giant cells, dyskeratosis, necrosis, ulceration
    • Feline immunodeficiency virus