Eczema/Dermatitis Flashcards
How is eczema broadly classified?
- Exogenous
- Endogenous
Give two examples of exogenous eczema
- Photosensitive dermatitis
- Contact dermatitis
- Allergic
- Irritant
Give three examples of endogenous eczema
- Atopic eczema
- Seborrhoeic eczema
- Venous eczema
- Asteatotic eczema: caused by dry skin
What is the commonest form of eczema?
Give two risk factors for this eczema
Atopic eczema: 10-20% children, 2-5% adults.
- 90% +ve FHx atopy
- Polygenetic + environmental influence
- Filaggrin deficiency: important for skin barrier
- Psychological stress
Describe the characteristic skin lesion of acute eczema
Papules and vesicles on an erythematous base
Describe three presenting features of atopic eczema
- Itchy red/dark skin lesions
- Poorly defined edges
- Bleeding
- Papules/vesicles on erythematous base (acute)
- Scaling/thickened (chronic)
- Weep/crust (infected)
- Commonly on face, scalp, and flexors
- Young children: extensors
- Psychological impact
- Sleep disturbance
- Social restrictions: school, job etc.
Outline the diagnostic criteria for atopic eczema
-
Itchy skin condition plus 3+ of the following
- History of pruritus in skin creases; cheeks in infants
- Atopy PMH; atopy FHx in children <4yr
- General dry skin in the preceding year
- Visible flexural eczema; cheeks and extensors in <4yr
- Onset in first 2yr of life
Outline the different severities of atopic eczema
- Clear: normal skin and no active eczema
- Mild: areas of dry skin, and infrequent itching
- Moderate: areas of dry skin, frequent itching, and redness
- Severe: widespread areas of dry skin, incessant itching, and redness
- Infected: weeping, crusted, or pustules; with fever or malaise.
What age group typically develop atopic Eczema?
<12yr
Tends to resolve by teenage years; may recur
What immunological response occurs in atopic eczema?
How does it compare to psoriasis?
- Both are type 4 hypersensitivity reactions
- Atopic eczema features a TH-2 response
- Extracellular organisms
- High IgE and eosinophils
- Psoriasis features a TH-1 response
- Intracellular organisms.
List three exacerbating factors of atopic eczema
- Infections
- Staph. aureus is the most important trigger
- Irritants: soaps; detergents
- Contact allergens
- Sweating
- Climate: worse in winter
- Dietary: predominently in children
- Severe stress
How does eczema present differently on non-caucasians?
- Caucasians: red lesions seen on flexors
- Non-caucasians: dark lesions seen on extensors
Which demographic is most at risk of seborrhoeic eczema?
Male
Teens-20s
How is seborrhoeic eczema diagnosed?
Diagnosed based on distribution
Which condition has increased risk of seborrhoeic eczema?
HIV
What is the commonest trigger of allergic contact dermatitis?
Nickel
How does allergic contact dermatitis present differently to other forms of eczema?
Random irregular distribution that fits with contact with triggers on clothing, piercings etc.
What investigation is used for allergic eczema?
Patch testing
Compare patch testing and skin prick test
- Patch test: Type 4 hypersensitivity
- Contact dermatitis
- Skin prick: Type 1 hypersensitivity
- Specific allergens; atopy
Explain the pathophysiology of venous eczema/gravitational dermatitis
- Poor venous drainage (eg. DVT, varicose veins)
- Venous pooling and HTN
- Activates innate immune system
Give three specific clinical features of venous eczema?
- Atrophie blanche
- “Champagne bottle” shape
- Induration (lipodermatosclerosis)
Why are elderly patients more prone to specific types of eczema.
Dry skin - asteatotic eczema
Normally Tx with moisturisers
What is the prognosis of eczema in young children?
50% resolve by age 6
90% resolve by teenage years
Outline the management of atopic eczema
- Education
- Avoiding irritants: cool temp; frequent baths; avoid soaps
- Antihistamines
- Non-sedating for severe itching or urticaria
- Sedating if disturbed sleep
What antibiotics are given in infected eczema?
- Flucloxacillin: commonly S. aureus or Strep
- Penicillin-allergic: Erythromycin or Clarithromycin
Provide three complications of eczema
- Chronic scratching
- Excoriation (raw worn)
- Lichenification (thick and leathery)
- Infection: Staph aureus (90%); Group A Strep
- Eczema herpeticum: HSV causes widespread infection and punched-out lesions.
- Psychological impact
- Effect on ADLs
- Sleep
- Mood
What is Eczema herpeticum?
Dermatology Emergency
- Widespread eruption of eczema with punched-out lesions
- due to Herpes simplex infection
- Serious complication of atopic eczema
- Systemically unwell with fever and malaise
How is Eczema herpeticum treated?
- Aciclovir
- Abx for any bacterial secondary infection
- Opthalmology and dermatology advice if eye area involved
Why is Eczema herpeticum a dermatological emergency?
- Herpes hepatitis: rapid progression to fulminant liver failure
- Encephalitis
- DIC
- Death (rare)
