B16. Primary skin lesions, basics of dermatohistopathology

• Scales
  • Detaching fragments of a thickened stratum corneum
  • Dry and usually whitish
• Erosion
  • Loss of epidermis
  • Heal without scarring
• Excoriation
  • Loss of papillary dermis
  • Heals with scarring
• Fissure
  • Painful, deep, linear opening of skin through the epidermis and into the dermis
• Rhagades
  • Cracks or tears in the skin caused by stretching of brittle skin
• Ulcer
  • Skin defect with loss of epidermis and upper papillary dermis
  • Usually leave scars
• Crust
  • Dried secretion
  • Red-brown crust – blood
  • Yellow crust – serum
  • Honey-coloured crust – purulent streptococcus exudate
  • Yellow-green crust – purulent staphylococcus exudate
• Scar
  • Permanent fibrous lesions
  • A result of the repair process
  • Hypertrophic scar = keloid scar
  • Atrophic scar
• Atrophy
  • Thinning of epidermis and dermis
• Lichenification
  • Increased thickness of epidermis
  • Cobblestone-like surface
  • A result of chronic rubbing or scratching