Terminology in dermatology

Primary skin lesions

Flat lesions
- Macule
  - A flat skin lesion < 1 cm in size with discolouration
- Patch
  - A flat skin lesion > 1 cm in size with discolouration
Infiltrative lesions
- Papule
  - An elevated palpable skin lesion < 0,5 cm in size
  - Epidermal
- Plaque
  - An elevated palpable skin lesion > 0,5 cm in size
  - Intradermal
- Tuber
  - An elevated palpable skin lesion whose infiltration involves the entire depth of the dermis
- Nodule
  - A circumscribed elevated lesion > 1 cm
  - In dermis and subcutis
- Tumor
  - Large solid mass of tissue
Fluid-filled lesions
- Vesicle
  - Small fluid-containing lesion
  - Intraepidermal
- Bulla
  - Large fluid-containing lesion
  - Intraepidermal or subepidermal
- Urtica/wheal
  - Transient oedema in the dermis
- Pustule
  - Collection of pus in or below the epidermis
Dermatopathological terms
- Acantholysis
  - Separation of epidermal cells due to dissolution of desmosomes
  - E. g. in pemphigus vulgaris
- Acanthosis
  - Hyperplasia of stratum spinosum
  - E.g. in acanthosis nigricans
- Hypergranulosis
  - Hyperplasia of stratum granulosum
  - E.g. in lichen planus
- Hyperkeratosis
  - Hyperplasia of stratum corneum
  - E.g. in psoriasis
- Papillomatosis
  - Hyperplasia and enlargement of dermal papillae
- Parakeratosis
  - Keratinocytes in stratum corneum retain their nuclei
  - E.g. in
    - Psoriasis
    - Dandruff
- Spongiosis
  - Intraepidermal oedema
  - E.g. in
    - Atopic dermatitis
    - Allergic contact dermatitis

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