Eczema Flashcards
Types of eczema
Atopic eczema Contact allergic dermatitis Irritant contact dermatitis Eczema Herpeticum Discoid Eczema Seborrhoeic eczema Lichen Simplex
Eczema - acute phase presentation
Erythematous lesions Oedema Relatively flat Scaling and crusting Papulovesicular
Eczema - chronic phase presentation
Lichenification - thickening due to the epidermis being scratched
Elevated plaques
Scaling
Histology
Spongiosis - Collection of fluid between the keratinocytes in the epidermis
Acanthosis - increased thickening of the epidermis
Atopic eczema - Cause
Genetic and environmental factors resulting in inflammation
Familial disease
Strong maternal inheritance
Formation of excessive IgE
Atopic eczema - Association with other conditions
Hayfever
Asthma
Atopic eczema - What is fillagrin
Skin barrier gene found in granular layer
Binds to water molecules so they retain water and therefore prevent water loss
Atopic eczema - Fillagrin
Fillagrin is MISSING in patients with eczema resulting in a defective skin barrier.
Easy penetration of microbes and allergens
Stimulation of immune system
Inflammatory response (IgE mediated)
Atopic eczema - Morphology
Dry skin Scaling Erythematous patches ill-defined borders Acute: can have papules and vesicles Chronic: more likely to have lichenification
Atopic eczema - Clinical presentation
Intense itch
Sleep disturbance
Cognitive impairment (due to lack of sleep)
Exaggerated skin markings (looks like wrinkles)
Atopic eczema - Commonly affected areas
Flexural distribution (behind knees, neck, front of wrists, elbows, ankles) - Can have eczema affecting extensor surfaces at beginning of disease
Atopic eczema - Diagnostic criteria
Itching + 3 of the following:
- visible flexural rash
- Hx of flexural rash
- personal history of atopy (hay fever, asthma)
- general dry skin
- onset in first 2 years of life
Atopic eczema - Complications
Secondary infection
- crusting indicates staph aureus
Atopic eczema - Investigations
Diagnosis is clinical
Confirm diagnosis by
- high serum IgE levels
- blood eosinophilia
Atopic eczema - Prognosis
Onset very early - eczema likely to clear up in teenage years
Onset later in childhood - eczema follows a more chronic course
Atopic eczema - Management (first line)
Avoid irritants and allergens
Emollients
Topical steroids - can be used long term if applied to correct areas
Topical immunomodulators - useful alternative to chronic use of potent steroid
Soap substitute
Anti-histamines - at night time
Antibiotics - if secondary infection present
Atopic eczema - second line management
Bandaging
Phototherapy
Systemic immunosuppressants - ciclosporin
Biologic therapy - azathioprine
Allergic contact dermatitis - hypersensitivity reaction
Type 4 (delayed)
Allergic contact dermatitis - cause
Contact with antigens such as:
- chemicals (perfume)
- topical therapies
- latex in gloves
- nickel in belts
Allergic contact dermatitis - Clinical presentation
Localised distribution where skin has come in contact with allergen
Sharp cut off point in skin
Reaction more severe at areas of thin skin - allergen an penetrate the skin quicker here
Allergic contact dermatitis - immunopathology
Allergen presented to skin
APCs (dendritc or langerhanns) recognise allergen
Allergen presented (by APC) to Th cells in dermis
Transported to lymph nodes where memory cells reside
If pt comes into contact with same allergen in future, there will be an immediate response due to generation of immunological memory
Allergic contact dermatitis - investigations
Patch test
Irritant contact dermatitis - causes e.g.
Soap Detergents Cleaning products Under a pts ring - soap stuck under ring not adequately washed off Nappy rash Mechanical oils at work
Irritant contact dermatitis - Clinical presentation
Non specific physical irritation
Irritant contact dermatitis - who gets it?
Anyone can get it Most common occupations: - hairdresser - mechanic - cleaner
Eczema Herpeticum - cause
Herpes Simplex Virus
Eczeam Herpeticum - morphology
Multiple monomorphic punched out crusty lesions
Eczema Herpeticum - management
Oral Aciclivir
Discoid Eczema - cause
Scratching
Discoid Eczema - morphology
Coin shaped eczematous lesions
Well defined
Can sometimes be confused with psoriasis
Discoid Eczema - commonly affected areas
Limbs
Seborrhoeic eczema - clinical presentation
In babies: cradle cap - yellowish thick crusts on scalp
In adults: dandruff, wide spread rash (not itchy)
Photosensitive eczema - cause
UV exposure
Photosensitive eczema - Clinical presentation
Cut off at t-shirt area is an important clue
Lichen simplex - cause
Scratching or rubbing the skin
