A common inflammatory skin condition. Commonly affects flexural areas. Multiple types and a spectrum of severity Wide range of external (exogenous) or internal (endogenous) factors can induce the condition

Eczema Flashcards by Chloe Lee

Describe the epidemiology of eczema

24% children
4% in western countries
60% cleared by adulthood

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What is eczema?

A common inflammatory skin condition.
Commonly affects flexural areas.
Multiple types and a spectrum of severity

Wide range of external (exogenous) or internal (endogenous) factors can induce the condition

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What is another name for eczema?

Atopic dermatitis

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How is the prevalence of eczema changing?

Increased prevalence of atopic eczema

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What is the clinical definition of atopic eczema?

An itchy skin condition in the last 12 months

Plus 3 of:
• Onset before 2yrs 
• History of flexural involvement 
• H. of generally dry skin 
• H. of other atopic disease

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What is the pathogenesis of eczema?

Genetics:
• Atopic FH: atopic eczema, asthma, hay fever (allergic rhinitis), food allergy
• Filaggrin gene

Epidermal barrier dysfunction
Environmental factors
Immune system dysregulation - TH2 overactive causing inflammation and leukocyte increase

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What are three pathologies on the skin?

Spongiosis (intercellular oedema) within the epidermis
Acanthosis (thickening of the epidermis)
Inflammation - superficial perivascular lymphohistiocytic infiltrate

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Describe normal structure of skin layers

Epidermis - outermost layer of skin

* Dermis - contains blood vessels, lymph vessels, hair follicles and sweat glands

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Describe the histology of acute dermatitis

Intercellular oedema within the epidermis
Accumulation of intra-epidermal vesicles
Infiltration of the epidermis with lymphocytes
Dermal changes include varying degrees of oedema and a superficial perivascular infiltrate with lymphocytes, histiocytes and occasional neutrophils and eosinophils.

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Describe the histology of chronic spongiotic dermatitis

Spongiosis is mild
Epidermal acanthosis (thickening of epidermis) - psoriasis pattern with hyperkeratosis and hypergranulosis
Fibrosis of papillary dermis

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What is spongiotic dermatitis?

Dermatitis that involves fluid buildup in your skin

Spongiosis is mainly intercellular oedema in the epidermis

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What are the clinical features of eczema?

• ITCH

Acute changes:
• Pruititus, erythema, scale, papules, vesicles
• Exudate, crusting, excoriation

Chronic changes:
• Lichenification (thickened skin), plaques, fissuring (split or crack)

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Describe the distribution of eczema

Flexure, neck, eyelids, face, hands and feet

* Tends to spare nappy area

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What is excoriation?

Obsessive-compulsive disorder. It is characterised by repeated picking at one’s own skin which results in skin lesions.

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Name other types of exogenous eczema

Contact dermatitis (irritant and allergic)
Lichen simplex
Photoallergic or photoaggravated

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Name other types of endogenous eczema

Atopic
Discoid
Venous
Seborrhoeic

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What is the pathogenesis of allergic contact dermatitis?

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 kind of reaction causes allergic contact dermatitis?

Type 4 hypersensitivity

* Delayed hypersensitivity (48-72hrs)

What are the two ways the skin is injured by in Irritant Contact Dermatitis?

Friction – micro-trauma, cumulative

2. Environmental factors

What are the environmental factors which can cause irritant contact dermatitis?

Cold
Over-exposed to water
Chemicals; acids, alkalis, detergents and solvents

What test can be used for allergic contact dermatitis?

Patch testing

What are the principles of patch testing?

Potential allergens applied
Baseline/standard series – applied to all patients
Applied Monday, remove Wednesday and re-assess Friday as you’re looking for a delayed hypersensitivity reaction

What are the clinical features of seborrhoeic dermatitis (infants)?

Distinctive pattern
Scalp, proximal flexures
< 6months age
Often clears within weeks of treatment

What are the clinical features of seborrhoeic eczema (adults)?

Chronic dermatitis.
Malassezia yeast increased in the scaly epidermis of dandruff
Red, sharply marginated lesions covered with greasy looking scales.
Distinctive distribution – areas rich in supply of sebaceous glands (scalp, face, upper trunk)

What do you treat seborrhoeic eczema?

Topical anti-yeast (ketoconazole) If severe, consider HIV test

What are the clinical features of discoid eczema?

* Circular plaques of eczema. * Cause often unknown. * May develop at sites of trauma/irritation.

What are the clinical features of pompholyx/vesiclar eczema?

* Palms and soles * Intense itch * < 40yrs * Sudden onset of crops of vesicles * Resolution can include desquamation

What are the clinical features of Asteatotic eczema?

* Very dry skin * Cracked scaly appearance * Most commonly shins affected * Climate – heat * Excessive washing/soaps

What are the clinical features of Venous eczema?

* Stasis eczema or varicose eczema * Increased venous pressure * Oedema * Ankle and lower leg involved Resolution of oedema can help – compression stockings.

What are the clinical features of Venous eczema?

* 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 is the treatment of eczema?

* Patient education * Avoid Causative / exacerbating factors * Emollients (moisturisers) * Soap substitutes * Intermittent topical steroids * Sometime antihistamines or antimicrobials * Calcineurin Inhibitors (Pimecrolimus)

What intermittent topical steroids can be used?

Different potency: • Hydrocortisone (low) • Betamethasone (potent)

What is the treatment of severe eczema?

Ultraviolet light. ``` Immunosuppression: • Azathioprine • Ciclosporin • Methotrexate • Mycophenolate mofetil ```

What is a possible side effect of prolonged steroid use?

Steroid induced striae (skin atrophy)

What are the two key features of eczema?

* Irritated skin | * Barrier dysfunction and inflammation

What is the filaggrin protein?

Protein of the epidermis and is vital for skin cells to mature properly into the tough, flat corneocytes that form the outermost protective layer of our skin

What does a mutation in the filaggrin gene increase risk of eczema?

Without filaggrin the outer protective layer does not form properly, the corneocytes dry out and the lipid layer is easily lost so that the skin becomes dry and cracked --> impaired barrier function

What is the different between seborrhoeic dermatitis and seb. eczema?

Seb. eczema is chronic seb. dermatitis

How was children with sea. dermatitis differ from those with seb. eczema?

Less itchy so child appears happier than with baby with eczema

What is the function of Calcineurin Inhibitors?

Immunomodulating agents; this means that they act on the immune system to reduce skin inflammation