Atopic dermatitis

Atopic dermatitis 

Updated: 02/24/2020

© Jun Wang, MD, PhD

General features
  • Usually starts in early infancy
  • Higher risk to develop other allergic disorders later in life
  • More common in women, Asians, Blacks, immigrants from developing countries into developed countries
  • Patients tend to have hypersensitive skin
  • Usually with family history of atopic dermatitis
  • Intermittent course with flares and remissions occurring, for unexplained reasons
  • Diagnosis based on clinical features, IgE reactivity and history of allergies
Pathogenesis
  • Most likely a combination of skin barrier defects and abnormal immune response
    • Filaggrin or SPINK5 mutation: causing increased epidermal permiability 
    • IgE sensitization
    • Imbalance between T cell subgroups
  • Cutaneous hyper-reactivity to environmental triggers
  • Skin barrier dysfunction worsened by inflammation
Clinical features
  • Incessant pruritus
  • Relatively age specific site of involvement
Early childhood: Face, extensor sides of extremities,
Older children or adults: Flexural surfaces, side of neck, popliteal and antecubital fossa
  • Primary physical findings including:
Xerosis: Dry skin
Lichenification: Thickening and hardening of skin 
Eczematous lesions

Infant atopic dermatitis
Childhood atopic dermatitis
Adult atopic dermatitis
  • More diffuse
  • Underlying background of erythema
  • Prominent xerosis
  •  Brown macular ring around the neck
Kaposi varicelliform eruption
  • AKA Eczema herpeticum
  • Cutaneous eruption caused by herpes simplex virus, coxsackievirus A16, or vaccinia virus
  • Infects preexisting dermatosis
  • Most commonly disseminated HSV infection in patients with atopic dermatitis
  • Associated with impaired immune function and mechanical barrier defect of affected skin
  • Clinical features
Sudden eruption of painful; edematous; crusted/hemorrhagic vesicles, pustules, or erosions
Areas of the preexisting dermatosis
  • Treated with antivirals
Pathological findings
  • Acute to chronic spongiotic dermatitis
  • Acute phase: Spongiosis, parakeratosis, lymphocytic exocytosis
  • Chronic phase: Epidermal hyperplasia
Management
  • Moisturization
  • Topical steroid
  • Immunomodulators


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