Atopic Dermatitis Flashcards
What is another name for eczema?
Dermatitis
Describe the appearance of dermatitis (eczema)
It is characterised by itchy, dry patches of papules and vesicles on an erythematous base.
What is the most common type of eczema?
Atopic dermatitis
Is eczema well or poorly demarcated?
Poorly
What are the endogenous types of eczema?
Atopic
Seborrhoeic
Varicose - from venous stasis
Discoid
What are the exogenous types of eczema?
Allergic contact (type IV sensitivity reaction) Irritant contact
When does atopic eczema usually develop by?
Early childhood (before age of 5) and resolves during teenage years (but may recur)
As eczema is itchy, what marks can be seen on the skin?
Excoriation marks
What are the causes of eczema?
Multifactorial
Family history of atopy often present e.g atopic dermatitis, asthma, allergic rhinitis (the atopic triad)
Genetic defect in epidermis barrier function - defects in the filaggrin protein
In infants, where on the body is atopic dermatitis usually found?
Face
Extensor aspects of limbs
In children and adults where on the body is atopic dermatitis usually found?
Flexor aspects of limbs
Also around eyes and on neck
Can involve scalp and abdomen
What are some complications of eczema?
Secondary bacterial infection- crusted weepy lesions
Secondary viral infection- molliscum contagiosum, viral warts, eczema herpeticum
Linchenification
What general measures can be done to treat atopic dermatitis?
Explain : management involves control not cure. It can fluctuate in its course
Identify and avoid triggers Avoid overheating Dress in soft fabrics Manage stress Keep fingernails short Try and stop children from scratching
Atopic dermatitis can worsen with allergens such as…
Soaps, detergents, shower gels
Abrasive or synthetic fabrics e.g wool, nylon
Skin infections
Extremes in temperature
Inhaled allergens - dust mites, pollen, pet dander, mould
Stress
Hormonal changes in women
What type of hypersensitivity reaction is atopic dermatitis?
Type 1 - starts off with something in environment e.g flower pollen that travels through porous skin and picked up by an antigen presenting immune cell. Allergen presented to naive helper T cell activating it into a Th2 cell - stimulates a B cell to produce IgE antibody specific for that pollen.
IgE binds to other immune cells e.g mast cells, basophils = sensitisation
If second exposure to pollen, the allergen cross links the IgE on sensitised cells - degranulation and release of pro inflammatory molecules
Causes nearby vessels to dilate and attract more immune cells to area creating inflammation in skin tissue. More allergen can enter skin and water can escape (skin becomes dry).
Scratching further damages skin barrier - vicious cycle
When is the itchiness often worse?
At night - no distractions
What topical measures can be used to treat atopic dermatitis?
Frequent emollient usage - best applied when skin moist, but applied at other times as well (ideally every 4 hours)
Topical steroids BD - weakest that controls disease effectively
Topical calcineurin inhibitors e.g tacrolimus if intolerant to / steroid therapy ineffective - does not thin skin like steroids, so useful on face
How do topical calcineurin inhibitors work? E.g pimecrolimus and tacrolimus
They are immunomodulators - they decrease lymphocytic proliferation
What oral treatment can be used to manage atopic dermatitis?
Oral antibiotics if signs of infection - 7 days of flucloxacillin
Antivirals if secondary viral infection
Antihistamines - ideally intermittently for exacerbations to reduce itch and scratch
Secondary care: immunosuppressive agents - cyclosporin, azathioprine, prednisolone
What percentage of children with eczema also have food allergies?
30%
Where is the incidence highest?
Developed countries in urbanised areas - affects 20-30% of children here
What is another term for itch?
Pruritis - the main feature!
Are bacterial infections a common complication?
Yes
How would a bacterial infection present?
Crusting
Weeping
Surrounding erythema - may look like cellulitis
