Dermatology 1

Dermatology 1

Dermatology 1

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The Skin

  • The largest organ of the body
  • Complex multilayered organ
  • Three major functions:
    • Protective - mechanical barrier
    • Homeostatic - temperature control
    • Sensing - organ of touch
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Skin Structure

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When Things go Wrong

  • Dermatological conditions affect up to 1/3 of the population at any one time
  • Dermatological conditions make up approximately 10% of GP consultations
  • 3 million patients are treated in UK outpatient clinics every year
  • Significant psychological impact on patients
  • Skin conditions may be the primary disease or may indicate a systemic disease
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Features of Diseased Skin

  • Nodule or papule
    • e.g. acne, squamous cell carcinoma
  • Plaque
    • e.g. psoriasis
    • elevated flat top lesion, >1cm in diameter, may appear with papsules
  • Bullae/blister
    • e.g. physical, infection, allergy
  • Macule
    • flat lesion not elevated, different colour to the surrounding skin, i.e. appearing like a freckle, large macules may be >5mm
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Features of Diseased Skin

  • Cyst
    • e.g. severe acne
    • deep seated mass filled with a semi solid or liquid material, most occur as a result of a blocked gland
  • Pustule
    • e.g. infection, acne, pustular psoriasis
    • lesions containing purulent material, often associated with hair follicles
  • Scale
    • e.g. dermatitis, eczema
    • excess corneocyte production and upset in the desquamation process, dry and whitish scales that flake from the skin surface
  • Others: fissure, erosion, ulcer, e.g. bed sore
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Assessing Skin Lesions

  • Site
  • Shape
  • Size
  • Symmetry
  • Sum
  • Shade
  • Scratch
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Questions to Ask

  • Are there any lesions that you have not examined?
  • Has the patient had this skin problem before?
  • How old are they?
  • How long has the patient been aware of the problem?
  • Is it getting worse?
  • Has the patient tried any treatment?
  • Is the patient taking any medicines currently?
  • Did the patient feel unwell before the problem first appeared?
  • Does the patient have any other illnesses?
  • Does the patient have any allergies?
  • Does it itch?
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Dermatological Therapy

  • Most skin conditions are treated topically
    • Targets the diseased area
    • Minimises system side effects
  • Stratum corneum acts as a significant barrier to topical therapy
  • Need to overcome this barrier to deliver effective treatment
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Topical Over the Counter Products

  • Emollients
    • Creams/ointments
    • Bath additives
    • Soap substitutes
  • Corticosteroids include
    • Hydrocortisone 1%
    • Clobetasone butyrate 0.05% (Eumovate)
  • Keratolytics include
    • Benzoyl peroxide, salicyclic acid, resorcinol, tar
  • Antibacterials include
    • Benzoyl peroxide, triclosan
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Topical Over the Counter Products

  • Antifungals (fungal infections)
  • Antiseptics (bacterial infections)
  • Antivirals (cold sores and other HSV (Herpes Simplex Virus) infections
  • Antihistamines (allergic rashes)
  • Parasiticidal preparations (head lice)
  • Anaesthetics (teething)
  • Antipruritics (reduce itching)
  • Skin 'dissolving agents' (warts, verrucae)
  • Compound preparations
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Dermatological Therapy

  • A number of factors influence drug penetration through the stratus corneum
  • Skin
    • Anatomical site of application
    • Skin temperature
    • Skin hydration
    • Skin integrity
  • Medicine
    • Partition coefficient
    • Concentration gradient
    • Vehicle
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Choice of Vehicle

  • The vehicle is the formulation in which the active ingredient is presented (i.e. cream or ointment)
  • Choice of vehicle is important because:
    • the relative solubility of drug in the vehicle and the stratum corneum influences drug penetration
    • vehicles themselves have an important therapeutic role
  • Creams
    • Use on: moist or dry skin
    • Main components: oil/water
    • Properties: moisturing, emollient, cooling
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Choice of Vehicle

  • Ointments
    • Use on: dry, scaly skin
    • Main components: water/oil
    • Properties: emollient, occlusive, greasy
  • Gel
    • Use on: greasy, weeping skin
    • Main components: usually water and polymers
    • Properties: cooling, spreads easily
  • Pastes
    • Use on: dry, scaly, lichenified skin
    • Main components: petroleum derivatives and powders
    • Properties: protective, messy
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Choice of Vehicle

  • Lotions
    • Use on: acute, weeping lesions
    • Main components: powder and water
    • Properties: soothing, cooling, drying
  • Dusting powders
    • Use on: skin folds
    • Main components: powder
    • Properties: reduce friction
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How much to use

  • The amount of topical treatment that should be used is dependent on:
    • the area being treated (location, size, integrity)
    • the active ingredient contained in the vehicle
    • the risk of side effects
  • Different products have different doses so make sure to counsel on use
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Folliculitis

  • Inflammation of the hair follicle, typically associated with infection
  • Localised pustules and erythema centred around hair follicles
  • E.g. shaving rash, jacuzzis, swimming pools
  • Management
    • Treatment: antibiotics 
    • Give lifestyle advice/avoidance tips
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Fungal Skin Infections

  • Dermatophyte infection - Tinea/ringworm
    • Tinea corporis
    • Tinea cruris
    • Jock itch/Dhobie itch
    • Feet and nails
  • Candida infection
    • Sweat/nappy rash
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Tinea corporis or Tinea cruris?

  • Tinea corporis
    • Red/pink, flat or slightly raised
    • Ring-shaped lesions with red, scaly borders with a clear central area
  • Tinea cruris
    • Red-brown, flat or slightly raised plaques
    • Active borders (pustules or vesicles)
    • Often itch, and in some cases there is uniform scale without central clearing
  • Transmission
    • Direct contact with an infected person
    • Indirect contact with items contaminated with the fungus, e.g. clothing, towels and bed sheets
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Tinea Treatment Strategy

  • Treated with imidazole creams (up to 4 weeks)
  • Treated with terbinafine cream (1-2 weeks)
  • Antifungal powder to reduce perspiration
  • Advice: hygiene, drying, towels, loose fitting clothes, feet
  • Refer: if severe or topical treatment fails
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Imidazole and Terbinafine Creams: P/GSL

  • Imidazole creams
    • Clotrimazole 1%, miconazole 2%
    • Fungistatic
    • Apply 2-3 times daily
    • 10-14 days after symptoms resolve
    • Up to 4 weeks treatment
  • Terbinafine creams
    • Lamisil
    • Fungicidal
    • Binds to keratin
    • Apply once daily
    • 1 week treatment
    • Residency in skin - not for under 16s
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When to Refer

  • Persistent
  • Recurrent
  • Severe
  • Immunocompromised
  • Treatment failure
  • Associated symptoms
  • Difficult diagnosis
  • POM treatments available include oral tablets
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Other Skin Infections

  • Impetigo
    • affects around mouth and nose
  • Viral Herpes Simplex Virus on skin, especially hands
    • not common but very severe so refer immediately if suspected
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Male/Female Pattern Baldness

  • Androgenetic alopecia
  • First occurs in men between the ages of 20 and 45
  • Follows a typical pattern of hair loss
  • Usually begins at the temples or on the crown
  • Initial thinning progressing to complete loss
  • Typical loss is over the top of the head 
  • Psychological distress and reduced quality of life
  • Genetic disposition
  • Anagen --> Catagen --> Telogen
  • High levels of dihydrotestosterone (DHT) have an adverse effect on the hair follicle cycle
  • DHT acts at receptors on hair follicles and slows down growth to produce weaker/shorter hair
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Male/Female Pattern Baldness: Treatment

  • Minoxidil (Regaine)
  • Potent antihypertensive drug
  • Hypertrichosis side effect
  • Topical solution 2% (GSL) or 5% (GSL/P)
  • Also available as a 5% foam
  • Regular application - twice daily
  • Patients with pre-existing heart problems should consult their doctor before using minoxidil
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Male/Female Pattern Baldness: Oral Treatment

  • Finasteride (Propecia)
  • A 5alpha-reductase inhibitor (POM)
  • Available on private prescription only
  • Dose is 1mg daily
  • Daily treatment is required for 3-6 months before any effect is seen
  • Reversed following discontinuation
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