Terminology

• Lesion

  Any single area of altered skin

  May be solitary or multiple
• Rash


  Widespread eruption of lesions
• Configuration of lesions:

  • Nummular/discoid lesion - round coin shaped lesions with no central clearing e.g. discoid eczema
  • Linear lesion - linear shape lesion that often occurs for some external reason such as scratching or striae
  • Target lesions - concentric rings like a dartboard e.g. erythema multiforme
  • Annular - lesions grouped in a circle with central clearing e.g. ring worm
• Lesion distribution:

  • Acral - distal extremities e.g. ears fingers, toes, penis and nipples e.g. lentiginous melanoma on fingernail
  • Dermatomal - confined to one or more segments of skin innervated by a single spinal nerve e.g. shingles
  • Extensor - extensor surfaces of limbs e.g. psoriasis
  • Flexural - related to flexion or skin folds such as back of knees, elbow crease, armpits and groin e.g. eczema
  • Follicular - within or around hair follicles
  • Generalised
  • Koebnerised - new lesion at sign of trauma - underlying dermatological condition
  • Photosensitive
• Colour of skin lesion:

  • Hyperpigmentation e.g. melasma
  • Hypopigmentation e.g. vitiligo
  • Telangiectasia e.g. BCC
  • Purpura - haemorrhage from small blood vessel, does not blanch. If <2mm called petechia
  • Ecchymoses aka bruises - larger extravasations of blood, does blanch
• Morphology of lesion:

  • Macule - small patch of skin that is altered in colour but not elevated e.g. freckle
  • Patch - large area of colour change with smooth surface
  • Plaque - circumscribed, palpable lesion more than 1cm in diameter, most are elevated e.g. psoriasis
  • Papule - elevated, solid, palpable lesion that is less than 1cm in diameter, located primarily in the epidermis
  • Nodule - elevated, solid, palpable lesion that is more than 1cm, located primarily in the dermis and hypodermis e.g. cyst
• Morphology of lesion:

  • Cyst - papule or nodule that contains fluid or semi-fluid material so is fluctuant, if became infected would be called an abscess
  • Pustule - circumscribed lesion that contains pus - filled with neutrophils and may be white or yellow
  • Abscess - localised collection of pus - deeper in tissue than pustule
  • Vesicle - small blister <1cm that contains liquid
  • Bulla - large blister >1cm that contains fluid
  • Wheel - transient elevation of skin due to dermal oedema, often pale centrally with an erythematous rim and without surface change
• Secondary changes:

  • Excoriation
  • Lichenification - chronic rubbing causes palpable thickened skin and lichenoid scale (white) - chronic atopic eczema and lichen simplex
  • Fissure
  • Ulcer - full thickness loss of epidermis and at least a portion of the dermis
  • Crusting - plasma exuding through eroded epidermis e.g. impetigo
  • Hypertrophy - limited to area of damaged skin
  • Keloid - excessive scar formation extending beyond original wound margin
  • Fungating - large malignant tumour