Culicoides Hypersensitivity

Also known as Sweet Itch

• Usually involves Type I reaction and Type IV reaction due to salivary antigens of Culicoides sp.
• May be seasonally recurring or continuous depending on climate
• Grossly:
  • Papules, crusts, alopecia, excoriations, lichenification
• Microscopically:
  • Superficial and dep perivascular dermatitis
  • Many eosinophils
  • Epidermal hyperplasia
  • Hyperkeratosis
  • Dermal fibrosis
  • Possibly eosinophilic folliculitis, intraepidermal pustules and eosinophilic granulomas