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DERMATOLOGY

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					DERMATOLOGY
               OBJECTIVES
   List functions of the skin
   Define and discuss different types of eczema
   Discuss management of eczema
   Outline symptoms/conditions requiring referral
    to doctors
   Skin is a vital organ that covers the entire
    outside of the body,
   Forms a protective barrier against pathogens
    and injuries from the environment.
   The skin is the body's largest organ; about 2 mm
    thick and weighs approximately six pounds.
   The skin also helps regulate body temperature,
    gathers sensory information from the
    environment, stores water, fat, and vitamin D,
    and plays a role in the immune system
    protecting us from disease.
   There are three layers in the skin:
-   Epidermis
-   dermis
-   and subcutaneous (or hypodermis).
                      Epidermis
   Outermost layer of the skin
   The thickness varies in different types of skin; it is only
    0.05 mm thick on the eyelids, and is 1.5 mm thick on
    the palms and the soles of the feet.
   The epidermis contains the melanocytes (the cells in
    which melanoma develops), the Langerhans' cells
    (involved in the immune system in the skin), Merkel
    cells and sensory nerves.
   The epidermis layer itself is made up of five sub layers
    that work together to continually rebuild the surface of
    the skin: basal, squamous, stratum granulosum, stratum
    lucidum, stratum corneum
                         Dermis
   The dermis is located beneath the epidermis and is the
    thickest of the three layers of the skin (1.5 to 4 mm
    thick), making up approximately 90 percent of the
    thickness of the skin.
   The main functions of the dermis are to regulate
    temperature and to supply the epidermis with nutrient-
    saturated blood.
   Much of the body’s water supply is stored within the
    dermis. This layer contains most of the skins specialized
    cells and structures, including: blood vessels, lymph
    vessels, hair follicles, sweat, sebaceous glands, nerve
    endings
                Subcutaneous
   innermost layer of the skin
   Consists of a network of fat and collagen cells.
   Functions as both an insulator, conserving the
    body's heat, and as a shock-absorber, protecting
    the inner organs.
   It also stores fat as an energy reserve for the
    body. The blood vessels, nerves, lymph vessels,
    and hair follicles also cross through this layer.
SKIN DISORDERS
                   ECZEMA
   Form of dermatitis or inflammation of the
    upper layers of the skin
   These include dryness and recurring skin rashes
    which are characterized by one or more of these
    symptoms: redness, skin edema, itching and
    dryness, crusting, flaking, blistering, cracking,
    oozing, or bleeding.
   Areas of temporary skin discoloration may
    appear and are sometimes due to healed lesions,
    although scarring is rare.
   2 types
-   Exogenous eczema: ppt by contact with agents
    in the environment
-   Endogenous eczema: no external cause is found
                     Diagnosis
  Generally based on the appearance of inflamed, itchy
   skin in eczema sensitive areas such as face, chest and
   other skin crease areas.
 Given the many possible reasons for eczema flare-ups,
   a doctor is likely to ascertain a number of other things
   before making a judgment:
- An insight to family history
- Dietary habits
- Lifestyle habits
- Allergic tendencies
- Any prescribed drug intake
- Any chemical or material exposure at home or
   workplace
   To determine whether an eczema flare is the result of an
    allergen, a doctor may test the blood for the levels of
    antibodies and the numbers of certain types of cells.
   In eczema, the blood may show a raised IgE or an
    eosinophilia.
   The blood can also be sent for a specific test called
    Radioallergosorbent Test (RAST) or a (PRIST). In the
    test, blood is mixed separately with many different
    allergens and the antibody levels measured. High levels
    of antibodies in the blood signify an allergy to that
    substance.
   Another test for eczema is skin patch testing

***SCORAD test
   Allergic contact dermatitis
-   Delayed hypersensitivity
    reaction involving allergens
    or antibodies
-   E.g. plants, rubber, nickel,
    cosmetics
-   Clears off after offending
    agent is removed
   Irritant contact
    dermatitis
-   Exposure to irritating
    chemicals or detergents
-   Usually on hands
   Photoallergic dermatitis
-   Delayed sensitivity to
    topical or systemic
    chemical agent with UV
    exposure
-   Allergens perfumes,
    sunscreens
-   Drugs sulphonamides,
    piroxicam, griseofulvin
   Phototoxicity                  Atopic Dermatitis
-   Direct tissue injury by     -   Allergic type action with
    phototoxic agent or             hayfever, asthma, very
    radiation                       dry skin
-   Appears like a sunburn      -   Associated with family
    on areas exposed                history, high levels of
-   Drugs: frusemide,               IgE
    thiazides, tetracyclines,   -   Red scaly eruptions, may
    retinoids                       be weeping or thickened
                                -   Secondary infection
                                    common
 Discoid Eczema
- Round disc like intense itchy erythematous
  scaling lesions
   Asteatotic Eczema: caused by drying of skin, dry
    cracked dermatitis
Varicose Dermatitis
Dyshidrotic Dermatitis
Seborrheic dermatitis
Lichen Complex
                   Treatment
   Identify cause aggravating factors, reduce itch
-   wool, synthetic clothing, soaps, detergents
-   Photosensitizing drugs
-   Raised temp, sweating
-   Preserved food, inhaled allergens, dust mites
   Improve skin hydration
-   ↓ frequency duration of showering
-   Use tepid water
-   Adding bath oils, using soap substitutes (refer to
    table in notes)
-   Using emollients
               Moisturizers
   Minimize dryness, prevent exacerbation
   Should be applied to exposed areas at regular
    intervals
   Apply before topical CS or at different times
   2 types:
-   Humectants: attract trans-epidermal water to
    stratum corneum and retain it e.g. glycerin, urea
-   Emollients: leave a film on surface, reduce water
    loss e.g. soft paraffin, dimethicone
                   Topical CS
   Used when emollients inadequate, check for
    secondary infection
   Choice depends on:
-   Age: hydrocortisone
-   Site: face, flexures mild topical CS, else where
    moderately potent CS
-   Lichen simplex and thick skin may require
    potent to very potent CS
               Practice Points
   Use potent preparations for shortest time, then
    stop
   Apply sparingly
   Regular correct use of emollients can reduce use
    of CS therefore advice patients appropriately
   For chronic dermatitis, avoid tolerance by
    applying on alternate days or having medication
    free periods
   BEWARE of potential misuse of topical steroids
              Tar preparations
   Coal tar, Ichthammol, wood tars
   Complex compounds, mechanism unclear
   Long lasting anti-inflammatory properties, fewer
    side effects than CS
   Less potent more messier
   Should not be applied to acutely inflamed skin,
    genitals due to irritation
   Useful for chronic lichen lesions
                      Others
   Astringents (normal saline, K permanganate)
    used in acute cases to dry weeping eruptions in
    localized areas
   Antiseptics: reduce risk of infection??
   Systemic CS: short course in acute allergic
    contact dermatitis
   Sedating antihistamines: useful at night due to
    excessive scratching
   Immunomodulating agents: severe disabling
    disease
   UV therapy: effective in unresponsive eczema,
    UVB, PUVA
   Antibiotics: secondary bacterial infection
   Pimecrolimus, tarcrolimus: immnomodulating
    agent , effectively suppress the immune system
    in the affected area, and appear to yield better
    results in some populations
   Herbal medicines
               Prevent relapse
   Avoid ppt factors
   Regular application of emollients
   Avoid soap
   Stress management
                    Referral
   Infections
   Inadequate response or no response after 7 days
    with recommended tx
   Severe eczema affects face, genitals
   Psoarisis
   Child < 12 or pregnant women
                Useful sites
   http://www.eczema.com.au/eczema.php
   http://www.netterimages.com/image/dermatol
    ogy.htm
   http://www.eczema.org/
   http://www.nlm.nih.gov/medlineplus/eczema.h
    tml
   http://www.dermnetnz.org/

				
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