Skin function and terminology Flashcards
Functions of the skin
Immunological barrier
Temperature regulation
Element/UV protection
Sensory and endocrine function
Skin structure
Stratum corneum
Epidermis
Dermis
Subcutaneous layer
Macule
A change in surface colour without elevation or depression (nonpalpable)
5-10mm
If there is some minor surface changes it is a ‘patch’
Papule
A circumscribed, solid elevation of the skin with no visible fluid
5-10mm
Nodule
A large papule >1cm, situated in the dermis or subcutaneous tissue
Differentiated from a papule by size and depth
Plaque
Can be a large papule or the confluence of papules
>1cm
May produce a plateau-like lesion where diameter is greater than depth
Vesicle
Bulla if large
A circumscribed, fluid containing epidermal elevation up to 5-10mm
Lichenification
Epidermal thickening with visible and palpable thickening of the skin with accentuated skin markings
Erosion
A discontinuity of the skin with incomplete loss of the epidermis. Generally moist and depressed
Ulcer
A discontinuity of the skin with complete loss of the epidermis and maybe the dermis and deeper structures.
Erythema
Redness due to hyperemia of capillaries
Pustule
A small skin elevation containing cloudy or purulent material made of necrotic inflammatory cells - may be white or red
Wheal
A rounded or flat topped pale red papule which is usually transient
Scaling
Dry or greasy laminated masses of keratin from the thickened stratum corneum
Desquamation
The collective shedding of sheets of thickened stratum corneum
Xerosis
Abnormal dryness of the skin or mucus membranes
Target Lesions
Typical lesion of erythema multiforme (EM)
Consists of dark, central papule/vesicle, pale intermediate zone and peripheral ring of erythema
Factors effecting skin function
Genetics, Body site, Irritants and detergent use
Proteases – inflammatory cells, house dust mites, Staph A
Corticosteroid use
Allergy testing
Skin prick test – Food allergies and pollen
Skin Patch test – contact dermatitis and irritants. takes 4 days
Radioallergosorbent test (RAST) – used for food allergies, inhaled allergens and wasp/bee venom. determines the amount of IgE and can be used when skin tests are not suitable (extensive eczema or anti-histamine use).
Hirsutism
Androgen dependent
Most commonly PCOS, also cushings, congenital adrenal hyperplasia, androgen therapy, obesity, phenytoin
Assessed by Ferriman-Gallwey scoring system (>15 is moderate or severe). Treat with weight loss or COC. Can use topical eflornithine (except in pregnancy or breastfeeding)
Hypertrichosis
Androgen independent
Minoxidil, ciclosporin and Diazoxide
Can be due to Congenital hypertrichosis lanuginosa or terminalis.
Porphyria cutanea tarda or anorexia nervosis.
