Photoenhanced Dermatoses

• Many immune-mediated cutaneous disease are made worse by sunlight
  • Lupus erythematosus
  • Dermatomyositis
  • Pemphigus erythematosus
• Vasculitis in extremities, especially white-haired horses
• Grossly:
  • Erythematous, well circumscribed crusted lesions or hyperkeratotic plaques
• Microscopically:
  • Vasculitis of superficial dermal vessels
  • Thrombi may be seen