Dermatology Flashcards
6 Functions of normal skin
(VIPSTAr)
- Protective barrier (against environment)
- Temperature regulation
- Sensation
- Vitamin D synthesis
- Immunosurveillance
- Appearance/ cosmesis
Structures of normal skin
= largest organ in the body
- 3 layers: epidermis, dermis, subcutaneous tissue
Epidermis: layers, major cell types
- 5 layers -> Stratum Basale, Stratum Spinosum, Stratum granulosum, Stratum lucidum, Stratum corneum (‘Come Lets Get Sun Burnt’)
- Each layer represents a different stage of maturation of the keratinocytes. Average epidermal turnover time (migration of cells from basal layer to corneum is about 30 days.
- Stratum lucidum is a layer that is present mainly in areas of thick skin such as the sole.
- Composed of 4 major cell types:
1. Keratinocytes - produce keratin as a protective barrier,
2. Langerhan cells - present antigens and activate T-lymphocytes for immune protection
3. Melanocytes - produce melanin, gives pigment to skin and protects cell nuclei from UV DNA damage
4. Merkel cells - contain specialised nerve endings for sensation
Principles of wound healing
‘VIP Room’
* Vascular -> formation of a fibrin clot, through vasoconstriction and platelet aggregation
* Inflammation -> vasodilation. Migration of neutrophils and macrophages.
* Proliferation -> granulation tissue (by fibroblasts) and re-epithelialization.
* Remodelling -> collagen fibre re-organisation, scar maturation
Skin appendages: hair types
Hair:
a. lanugo: fine long hair covering shoulders, back and face of fetus/newborn). Typically shed before/shortly after birth.
b. vellus hair: fine, short, blond hair on all body surfaces/ peach fuzz. Develops during childhood.
c. terminal hair: coarse, pigmented, long hair on scalp, eyebrows, eyelashes. After puberty - face (beard), armpits, chest, pubic regions
Hair follicle and growth cycle
- Hair follicle -> divided into hair shaft (keratinised tube) and a hair bulb (actively dividing cells), and melanocytes which give pigment to the hair.
- Growth cycle -> anagen (long growing phase), catagen (short regressing), telogen (resting/shedding)
Skin appendages: nails
- Made up of a nail plate (hard keratin) which rests on nail bed.
- Nail bed contains blood capillaries, gives pink colour of nails
Skin appendages: Sebaceous glands
- Produce sebum via hair follicles. Lubricates and waterproofs the skin.
- Stimulated by conversion of androgens to dihydrotestosterone and therefore become active at puberty.
Skin appendages: Sweat glands
- Regulate body temp and are innervated by the sympathetic nervous system.
- Eccrine sweat glands -> universally distributed in the skin
- Apocrine sweat glands -> found in axillae, areola, genital and anus. Only function from puberty and action of bacteria on the sweat produces body odour.
Pathology linked to the epidermis
- Psoriasis -> change in epidermal turnover time - Ulcer, Scales, Crusting, Exudate -> change in surface of the skin or loss of epidermis - Hypo or hyper-pigmented skin -> Changes in pigmentation of skin
Pathology linked to the dermis
- Ulcers, papules, nodules -> changes in contour of skin or loss of dermis
- Acne, Disorders of hair -> disorders of skin appendages
- Erythema, Urticaria, Purpura -> changes related to lymphatic and blood vessels
Pathology linked to nails
- Pits and ridges -> abnormalities of nail matrix.
- Splinter haemorrhage -> abnormalities of nail bed
- Discoloured nails, thickening of nails -> abnormalities of nail bed
Pathology linked to sebaceous glands
Acne -> increased sebum production and bacterial colonisation
Pathology linked to sweat glands
- Hidradenitis suppurativa -> inflammation/infection of apocrine glands.
- Hyperhidrosis -> overactivity of eccrine glands
Derm Hx: PC
- nature, site and duration of problem
Derm Hx: HPC
- Initial appearance and evolution of lesion
- Sx (particularly itch and pain) -> systemic, oral/nail/hair loss, joint and muscle
- Aggravating and relieving factors
- Previous and current tx (effective or not)
- Recent contact, stressful events, illness and travel
- History of sunburn and tanning machines
- Skin type
Derm Hx: PMH
- history of atopy (e.g. asthma, allergic rhinitis, eczema)
- history of skin cancer and suspicious skin lesions
Derm Hx: FH + SH
- FH of skin disease
- Occupation (incl skin contacts at work)
- Improvement of lesions when away from work
Derm Hx: Further q’s
- medications and allergies
- impact on QOL
Derm examination: inspect + describe
- Inspect: general, site and number of lesions (distribution)
- Describe the individual lesion: SCAM
Size (widest diameter), Shape
Color
Associated secondary change
Morphology, Margin (border) - If pigmented, ABCD
- Asymmetry (lack of mirror image in any of 4 quadrants)
- irregular Border
- 2+ Colors within lesion
- Diameter >6mm
Derm exam: palpate + systemic check
Palpate: surface, consistency, mobility, tenderness, temperature
Systemic check: nails, scalp, hair, mucous membranes. General all systems.
Define Macule and Patch
Macule: Small (less than 1cm), smooth area of colour change. Ex// freckle, petechiae
Patch: Large (greater than 1cm), smooth area of colour change. Ex// Vitiligo, port wine stain
Define Macule and Patch
Macule: Small (less than 1cm), smooth area of colour change. Ex// freckle, petechiae
Patch: Large (greater than 1cm), smooth area of colour change. Ex// Vitiligo, port wine stain
Define Papule, Nodules and Plaque
- Papule: palpable + raised lesion <0.5cm. Ex// wart, mole, acne, angioma, xanthomata
- Nodule: palpable + raised lesion >0.5cm with deeper component. Ex// Cyst, Pyogenic granuloma.
- Plaque: palpable flat lesion. Can be scaly. Ex// Psoriasis.
Define Vesicle, Bulla, Pustule
- Vesicle: small <0.5cm, fluid filled blister.
Ex// Herpes, sunburn, pompholyx - Bulla: Large >0.5cm, fluid filled blister.
Ex// Herpes/infection, sunburn, pemphigoid - Pustule: pus-containing raised lesion.
Ex// Acne
Define Wheal, Scar, Ulcer, Fissure
- Wheal: transient raised lesion due to dermal oedema. Usually with swelling, burning or itching.
Ex// Hives - Scar: New fibrous tissue occurring post-wound healing.
Ex// Keloid scar - Ulcer: Break in skin - Loss of epidermis and dermis. Ex// Leg ulcer
- Fissure: Epidermal crack often due to excess dryness. Ex// Eczema
Define Naevus, Comedone, Abscess, Purpura
- Naevus: A localise malformation of skin structures
- Comedone: A plug in sebaceous follicle containing altered sebum, bacteria and cellular debris. Present as open (blackheads) or Closed (whiteheads)
- Abscess: Localised collection of pus surrounded by damaged and inflamed tissue
- Purpura: Red/purple non-blanching rash consisting of numerous petechiae (small, round non-blanching red/purple spots).
Nails: define clubbing, koilonychia, oncholysis, pitting
- Clubbing: loss of angle between posterior nail fold and nail plate
-> suppurative lung disease, cyanotic heart disease, IBD, idiopathic - Koilonychia: Spoon-shaped depression of the nail plate
-> IDA, congenital, idiopathic - Onycholysis: Separation of distal end of nail plate from nail bed -> trauma, psoriasis, fungal nail infection, hyperthyroidism
- Pitting: punctuate depressions of nail plate -> psoriasis, eczema, alopecia
Examples of inflammatory skin conditions? how spread between people? General aims of treatment
- Atopic eczema, acne, psoriasis
- Not infectious
- Mx: achieving control and not providing a cure
anatomy/physiology of acne
- An inflammatory disease of the pilosebaceous follicle
- Causes: hormonal (androgen) -> increase sebaceous glands. Abnormal follicular keratinisation. Bacterial colonisation.
FURTHER:
-SEBACEOUS GLANDS produce oily substance sebum, responsible for keeping the skin and hair moisturized. During adolescence, sebaceous glands will typically ENLARGE and produce more sebum under the influence of hormones.
- BACTERIA Propionibacterium acnes is a normal inhabitant of the skin. It uses sebum as a nutrient for growth and will continue to grow in line with the production of sebum.
- The presence of the bacteria attracts WBC’s to follicle. These immune cells produce an enzyme that damages the wall of the follicle, releasing debris into the hair shaft and deeper in the middle layer of skin to (the dermis). This process causes an inflammatory reaction that gives rise to a little red bump (called a papule), which can then develop into a pus-filled blister (called a pustule)
Presentation of Acne Vulgaris
- Non-inflammatory lesions (mild acne) -> open and closed comedones
- Inflammatory lesions (moderate-severe) -> papules, pustules, nodules.
- Commonly affects the face, chest and upper back.
Management of Acne Vulgaris
- Topical therapies (mild acne):
Benzoyl peroxide (antibac)
Antibiotics (antibac)
Retinoids (desquam +
comedolytic) - Oral therapies (moderate to severe):
Antibiotics e.g. tetracyclines
Anti-androgens
Retinoids e.g. Isotretinoin
(severe)
What is psoriasis
- A chronic inflammatory skin disease due to HYPERPROLIFERATION of KERATINOCYTES in the epidermis and INFLAMMATORY cell infiltration.
Types of psoriasis
- Plaque psoriasis: thickened erythematous lesions with silvery SCALES.
- Guttate: Commonly children. Many small raised PAPULES across trunk + limbs. Often triggered by STREP throat infection, medication, stress.
- Pustular: rare, SEVERE form. PUSTULES form under erythematous lesions. (emergency)
- Erythrodermic: EXTENSIVE ERYTHEMATOUS inflamed areas covering most of the surface area of the skin. Raw exposed areas when skin comes away. (emergency)