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Primary and secondary skin lesions

Skin is a mirror of systemic disease. Examination of skin will reveal specific sign of systemic disease.
Skin lesions can be classified as 
Primary skin lesions
  • Macules are flat lesions < 1cm circumscribed alteration of color of skin <1cm
  • Papules are palpable solid elevation < 1cm .Maculopapular rash include both macule and papule
  • Plaque are papular lesions of size > 1cm
  • Patch is a circumscribed alteration of color of > 1cm.
  • Vesicles are lesions < 1 cm these are fluid filled epidermal elevations.
  • Bullae are > 1cm fluid filled elevation 
  • Pustules are epidermal elevations < 1cm containing pus
  • Nodule areSolid palpable lesion ->0.5 cm
  • Papilloma - Pedunculated projecting lesion
  • Wheal - Elevated central white lesion with red margin
  • Telangiectasia - Dilated small cutaneous blood vessel
  • Petechiae - Pinhead size macule of blood into the skin.
  • Purpura -Larger petechiae which do not blanch on pressure
  • Ecchymosis -Large extravasation of blood into resulting in  haematoma 
  • Erythema - Redness of the skin.
Secondary skin lesions are the following
  • Scales—Desquamated epithelium
  • Ulcers—Loss of epidermis, dermis and often with loss of underlying tissue
  • Crust are dried up exudates
  • Scar are replacement by fibrous tissue
  • Excoriation are Loss of skin substance produced by scratching
  • Fissure—Any linear slit or discontinuity of skin.