Atopic Dermatitis

A chronic, relapsing inflammatory skin disorder associated with personal or family history of atopy

Aetiology

Multifactorial involving:
  • Genetic predisposition
    • Filaggrin gene mutation → impaired skin barrier function
  • Immune dysregulation
    • Th2-mediated hypersensitivity → ↑ IgE
  • Skin barrier dysfunction
    • Increased water loss → dry, sensitive skin
  • Environmental triggers
    • Irritants, temperature changes, allergens, stress
Most patients have elevated serum IgE levels.

Clinical presentation

Hallmark: Intense itching (pruritus)
Lesion types vary with age:
Infants (0–2 years)
  • Erythematous, oozing, crusted plaques
  • Primarily on cheeks, scalp, extensor surfaces
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Children (2–12 years)
  • Lichenification (thickening) with dry papules/plaques
  • Affects flexural areas (antecubital, popliteal fossae)
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Adults
  • Chronic lichenified eczema
  • Hands, eyelids, neck, flexures
  • Possible generalized dry skin and itch
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Associated findings:
  • Xerosis (dry skin)
  • Dennie-Morgan infraorbital folds
  • Keratosis pilaris
  • Allergic shiners (dark under-eyes)
  • Nipple eczema, hand eczema

Investigations

  • Primarily clinical
Hanifin & Rajka criteria (3 major + 3 minor) used in diagnosis
Major Criteria
  • Pruritus (intense itching)
  • Typical morphology and distribution
    • Flexural involvement in adults
    • Facial/extensor involvement in infants and children
    • Chronic or relapsing dermatitis
  • Chronic or relapsing course
  • Personal or family history of atopy
    • Asthma, allergic rhinitis, or atopic dermatitis
No specific lab test, but IgE may be elevated.

Management

Goal: restore skin barrier + control inflammation & itch.

Skin Care (Foundation of Treatment)

  • Daily emollients/moisturizers (thick creams/ointments)
  • Lukewarm baths, limit long hot showers
  • Use fragrance-free, mild soap
  • Avoid known triggers

Anti-inflammatory Treatment

  • Topical corticosteroids
    • First-line for flare-ups (choose potency based on severity/location)
      • Infants → Hydrocortisone 0.5–2.5%
      • Children & Adults → Triamcinolone acetonide 0.1% (ointment), Clobetasol propionate 0.05%
  • Topical calcineurin inhibitors
    • Tacrolimus, pimecrolimus (good for face and long-term use)
  • Topical phosphodiesterase-4 inhibitors
    • (e.g., crisaborole) in some cases

Antipruritic therapy

  • Oral antihistamines for itch relief
  • Wet wrap therapy in severe flare-ups

Infection management

  • Treat Staphylococcus aureus superinfection if present
  • Consider bleach baths for recurrent infections

Moderate–Severe or Refractory Cases

  • Phototherapy (UVB)
  • Systemic agents:
    • Cyclosporine, methotrexate, azathioprine
    • Dupilumab (IL-4/IL-13 inhibitor biologic) for severe AD

Complication

  • Secondary bacterial infection (impetigo)
  • Viral infections (eczema herpeticum)
  • Sleep disturbances due to itching
  • Lichenification due to chronic scratching