Eczema Flashcards
What % of children will be diagnosed with eczema in their childhood?
24%
How is eczema also known as?
Atopic dermatitis
What % of cases of eczema in children have cleared by the time they reach adulthood?
60%
What are some theories for the increasing prevalence of eczema, particularly in developed countries?
– Social class effect?
– Commoner in cooler climates?
– Pollution? Other environmental factors?
Hygiene hypothesis?
Describe the Modified Hanifin and Rajka criteria for the definition of atopic dermatitis
An itchy skin condition in the last 12 months + 3 of the following:
• Onset before age 2
• History of flexural involvement
• History of generally dry skin
• History of other atopic disease
– History in 1st degree relatives if under 4 yo
What gene plays a key role in the pathogenesis of eczema?
Filaggrin gene
What components are involved in the pathogenesis of eczema?
Genetics – Many genes implicated – Key role for Filaggrin gene – Atopic family history • Atopic eczema, asthma, allergic rhinitis, food allergy
Epidermal barrier dysfunction
Environmental factors
What 3 processes are involved in the pathology of eczema?
Spongiosis (intercellular oedema) within the epidermis.
Acanthosis (thickening of the epidermis).
Inflammation - Superficial perivascular lymphohistiocytic infiltrate.
What are the clinical features of eczema?
Itch!!
• Distribution
– Flexures, Neck, Eyelids, Face, Hands and feet
– Tends to spare nappy area
Acute changes
– Pruritus, Erythema, Scale, Papules, Vesicles
– Exudate, crusting, excoriation
Chronic changes
– Lichenification, Plaques, Fissuring
List some external/exogenous types of eczema
Contact dermatitis - irritant or allergic
Lichen simplex
Photoallergic or photoaggravated eczema
List some endogenous/internal types of eczema
– Atopic – Discoid – Venous – Seborrhoeic dermatitis – Pompholyx – Juvenile plantar dermatitis
What type of eczema does contact dermatitis come under?
Exogenous/external eczema
What type of eczema does lichen simplex come under?
Exogenous/external eczema
What is lichen simplex?
Hyperpigmented, lichenified plaque with accentuated skin lined caused by repeated rubbing of the area. Lichen simplex chronicus (LSC) is a localized, well-circumscribed area of lichenification (thickened skin) resulting from repeated rubbing, itching, and scratching of the skin
What type of eczema does Photoallergic or photoaggravated eczema fall under?
Exogenous/external eczema
What type of eczema does Atopic dermatitis fall under?
Endogenous/internal eczema
What type of eczema does discoid eczema fall under?
Endogenous/internal eczema
What type of eczema does venous eczema fall under?
Endogenous/internal eczema
What type of eczema does Seborrhoeic dermatitis fall under?
Endogenous/internal eczema
What type of eczema does Pompholyx or vesicular eczema full under?
Endogenous/internal eczema
What type of eczema does Juvenile plantar dermatitis fall under?
Endogenous/internal eczema
Describe asteatotic eczema
Asteatotic - diminished or arrested action of the sebaceous glands
Characterized by pruritic, dry, cracked, and polygonally fissured skin with irregular scaling, often on shins of elderly patients
Describe allergic contact dermatitis
Type 4 Hypersensitivity
Delayed hypersensitivity – can take 48-72 hrs to develop reaction
Antigen presenting cells take hapten/ allergen to LN and present to naive T cells
Clonal expansion of these T cells, released into blood stream
When these T cells next encounter hapten
– Mast cell degranulation, vasodilatation and neutrophils
What type of reaction is involved in allergic contact dermatitis?
Type 4 Hypersensitivity (delayed)
How long after exposure does allergic contact dermatitis flare?
Delayed hypersensitivity – can take 48-72 hrs to develop reaction
Describe irritant contact dermatitis
Skin injured by:
– Friction – micro-trauma, cumulative
– Environmental factors e.g.Cold, over-exposure to water
chemicals such as acids, alkalis, detergents, solvents
What occupations are at risk of irritant contact dermatitis
– Hairdressers
– NHS staff
– Cleaners
How do we test for allergens?
Patch testing
Potential allergens are applied on the monday and covered
Washed off on wednesday
Examine on friday for results
Describe Seborrhoeic eczema
Symptoms include red, scaly, greasy, itchy, and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the scalp, face, and chest
In babies, when the scalp is primarily involved, it is called cradle cap.
Dandruff is a milder form of the condition, without associated inflammation
How does Seborrhoeic eczema present in infants?
- Distinctive pattern
- Predilection for scalp (cradle cap), proximal flexures.
- <6months age usually.
What type of eczema is linked to cradle cap and dandruff?
Seborrhoeic eczema
Describe discoid eczema
- Circular plaques of eczema.
- Cause often unknown.
- May develop at sites of trauma/irritation.
Describe Pompholyx/vesicular eczema
- Affects palms and soles with vesicles/bullae
- Intensely itchy.
- Sudden onset of crops of vesicles.
- Resolution can include desquamation (peeling)
What age group is most commonly affected with Pompholyx/vesicular eczema?
< 40yo
What is Asteatotic eczema linked to?
- Climate – heat
* Excessive washing/soaps
Describe Venous eczema/venous stasis eczema
- Stasis eczema or varicose eczema.
- Increased venous pressure.
- Oedema.
- Ankle and lower leg involved.
- Resolution of oedema can help – compression stockings.
How can venous eczema be treated in addition to classic eczema therapy?
Compression stockings
What is eczema herpaticum?
- Disseminated viral infection
- Fever and often unwell
- Itchy clusters of blisters and erosions
- Herpes Simplex 1 and 2
- Swollen lymph glands
- Consider admission, antivirals, consider secondary bacterial infection.
What viruses are involved in eczema herpaticum?
HSV 1 and 2
Describe the signs of infected eczema
o Fluid oozing from the skin o A yellow crust on the skin surface o Small yellowish-white spots appearing in the eczema o The skin becoming swollen and sore o Fever and generally feeling unwell
What increases the risk of infected eczema?
Scratching
Not using treatment properly
How is eczema treated?
Patient education
Avoid Causative / exacerbating factors
Emollients (moisturisers)
Soap substitutes
Topical steroids e.g. Hydrocortisone, Betamethasone
Sometimes need antihistamines or antimicrobials
Calcineurin Inhibitors e.g. topical Pimecrolimus, Tacrolimus
Describe the different types of emollients used in eczema treatment
– Ointment – greasy but effective
– Creams – lighter
– Lotions – more watery
Describe a low potency intermittent topical steroid used in eczema treatment
Hydrocortisone
Describe a high potency intermittent topical steroid used in eczema treatment
Betamethasone
What are calcinuerin inhibitors?
Immunomodulators
Give two examples of calcinuerin inhibitors
Topical Pimecrolimus and Tacrolimus
How is severe eczema treated?
Ultraviolet light. Immunosuppression. – Azathioprine – Ciclosporin – Mycophenolate mofetil – Methotrexate
List 4 immunosuppressive agents used in severe eczema
– Azathioprine
– Ciclosporin
– Mycophenolate mofetil
– Methotrexate
Name the topical PDE-4 inhibitor recently approved by the FDA for eczema
Crisaborole
What is Dupilumab?
– 1st biologic for eczema patients
– IL-4/IL-13 inhibitor
What is the first ever biologic developed for eczema, and acts as a IL-4/IL-14 inhibitor?
Dupilumab
