Common Skin Disorders

• What is dry skin characterized by?

  A lack of water in the stratum corneum
• What is the normal water content of the epidermis?

  About 10-20%
• What happens to the epidermis in dry skin?

  It loses its normal flexibility, leading to roughness, fissures, and inflammation

  
• What maintains the thickness of the stratum corneum?

  The balance between keratinocyte production and corneocyte shedding
• What role do protease enzymes play in skin health?

  They cleave corneodesmosomes, allowing for the shedding of corneocytes
• How does humidity affect skin hydration?

  Reduced humidity decreases skin water content and protease enzyme activity
• What effect do soaps and detergents have on the skin?

  They disrupt the structure of intercellular lipids and reduce hydration
• How does UV radiation affect the stratum corneum?

  It impairs the barrier leading to increased water loss

  
• What does the "outside-in" theory suggest about atopic eczema (AE)?

  It suggests that genetic susceptibility leads to a defective skin barrier, allowing allergens to enter and provoke inflammation.
• What discovery in 2006 supported the "outside-in" theory?

  Loss-of-function mutations in the gene coding for filaggrin (FLG) were found to cause ichthyosis and predispose to AE.
• What role does filaggrin play in skin health?

  Filaggrin is a protein required for an intact skin barrier and contributes to the natural moisturizing factor.
• Why do not all individuals with FLG mutations develop AE?

  Because the alternative "inside-out" hypothesis suggests a dysfunctional immune response may also play a role.
• What is the consequence of a breached skin barrier in AE?

  It leads to water loss, skin drying, and provides entry for allergens and irritants.

  
• What is the "scratch-itch" cycle in AE?

  It is a vicious cycle where scratching damages the skin, leading to inflammation and further itching.
• What sensation do patients with dry skin experience due to loss of water?

  Patients perceive a sensation of "tightness."
• How do emollients function in treating dry skin?

  • Form a protective oily layer over the skin
  • Prevent water loss and improve hydration
  • Provide relief from cracking
  • Create a barrier against allergens and irritants
• What are humectants found in some emollient products?

  Humectants such as urea, lactic acid, or glycerol attract and retain water in the skin.
• What is the most important factor in choosing an emollient?

  Patient preference is the most important factor.
• What are the guidelines for managing atopic eczema according to NICE?

  • Emollients are recommended for all patients with atopic eczema.
  • Guidelines apply to patients with mild, moderate, and severe disease.
  • Emollients should be used frequently and on the whole body.
• How should emollients be applied for best results?

  Emollients should be applied frequently and immediately after washing or bathing.
• What is the recommended quantity of emollients for patients?

  Patients should be prescribed 1-1.2 kg of emollients per month.
• What is the recommended order of applying emollients and topical steroids?

  Apply the emollient first and leave a 30-minute gap before applying the topical steroid.
• What general advice should be given to patients on the use of emollients?

  • Use emollients to wash and bathe, avoiding soaps.
  • Apply emollients liberally and frequently.
  • Pat the skin dry after bathing and apply emollients immediately.
  • Use a downward stroking motion to apply emollients.
  • Prefer pump dispensers to avoid contamination.
• What are the physiological effects of topical steroids?

  Topical steroids have anti-inflammatory and immunosuppressive actions.
• What are the four potency classes of topical steroids in the UK?

  Mild, moderate, potent, and very potent.
• What is the significance of steroid potency?

  Potency influences the effectiveness and safety of the steroid treatment.
• How do changes in the steroid molecule affect its potency?

  Alterations in the structure can influence binding to the steroid receptor and thus its potency.
• What is the mode of action of topical corticosteroids?

  They bind to glucocorticoid receptors, modulating inflammation-related gene transcription.
• What are the common signs of bacterial infection in eczema?

  Signs include red, weepy skin with yellow crusts, pustules, fever, and soreness.
• How should infected eczema be managed?

  Infected eczema is best managed with oral antibiotics like flucloxacillin.
• What are the two calcineurin inhibitors available for eczema treatment?

  • Tacrolimus (Protopic®)
  • Pimecrolimus (Elidel®)
• What is the mode of action of calcineurin inhibitors?

  They inhibit T cell proliferation and the release of inflammatory cytokines.
• What is the recommended use of calcineurin inhibitors?

  They are considered a second-line treatment option for moderate to severe eczema.
• What are the systemic treatments for eczema?

  • Ciclosporin
  • Azathioprine
  • Oral corticosteroids
  • Mycophenolic mofetil
  • Methotrexate
• What is the purpose of phototherapy in treating eczema?

  Phototherapy has immunosuppressive effects and can improve disease severity.
• How often is phototherapy typically administered?

  Phototherapy is normally administered 3 to 5 times per week.
• What is Dupilumab used for?

  Dupilumab is a monoclonal antibody licensed for the management of moderate to severe AE.
• What are the potential benefits of phototherapy for patients with AE?

  • Immunosuppressive effects
  • Alters cytokine production
  • Causes apoptosis of infiltrating T-cells
  • Inhibits antigen-presenting function of Langerhans cells
  • Induces epidermal hyperplasia
• What are the three phototherapy modalities mentioned?

  Narrow-band UVB, broad-band UVB, and PUVA
• Why is PUVA less studied for atopic eczema (AE)?

  There are fewer studies on its use in AE compared to psoriasis