Eczema Flashcards
What is eczema?
Eczema is a prototypic example of a spongiotic reaction pattern with multiple clinical patterns
What are the 3 main types of eczema?
- Atopic eczema
- Irritant contact eczema
- Allergic contact eczema
What is atopic eczema?
Atopic eczema is a form of eczema beginning in childhood, caused by genetic and environmental factors, resulting in inflammation
What is the most common mutation in atopic eczema?
The filaggrin gene is most commonly affected in atopic eczema
There is often a family history of atopy or allergy
How will atopic eczema present?
Atopic eczema will present with:
- Pruritus (Itch)
- Ill-defined erythema and scaling
- Generalised dry skin
- Affecting flexor surfaces
What condition is shown?
Atopic eczema
What are some chronic skin changes that can occur in atopic eczema?
- Lichenification
- Excoriation
- Secondary infection
What are some infections that can occur on skin affected by atopic eczema?
Staphylococcus aureus (Causes crusting)
Herpes simplex virus (Eczema herpeticum)
How will eczema herpeticum (HSV) present?
Monomorphic punched-out lesions
What are the diagnostic criteria of atopic eczema?
Diagnosis requires itching plus 3 or more of the following:
- Visible flexural rash
- History of flexural rash
- Personal history of atopy (Or 1st degree relative if under 4y/o)
- Generally dry skin
- Onset before age of 2
In infants, cheeks and extensor surfaces may be affected
What is irritant contact eczema?
This is a form of eczema provoked by contact with water, detergents and chemicals
How will irritant contact eczema present?
- Erythema
- Scaling
- Fissuring
- Lichenification
- Nail dystrophy
- Crusting
This most commonly affects the hands
What is nappy rash?
A form of irritant contact dermatitis to urine with ulceration
What condition is shown?
Irritant contact eczema
What is allergic contact eczema?
Allergic contact eczema is a form of eczema that occurs when a person is sensitised to a usually tolerated environmental antigen
What are some common examples of allergic contact eczema?
- Nickel
- Hair dyes
- Fragrances
Describe the pathophysiology of allergic contact eczema
This occurs because Langerhans cells present the antigen to T-lymphocytes
Sensitised memory T-cells in the nodes recognise the antigen and send T-lymphocytes to the epidermis
The next time the person is in contact with this substance, a spongiotic eczematous reaction will occur with inflammation and presence of eosinophilia
This is a delayed type (Type IV) hypersensitivity reaction
What condition is shown?
Nickel allergy from belt buckle
How is allergic contact eczema diagnosed?
This is diagnosed using patch testing, in which batteries of allergens are placed in small wells and are applied to the skin of the back for 48 hours
A reaction of wheals (Urticaria) should occur within 96 hours, which are very itchy and can last 2-6 hours
What other pattern of eczema is shown?
Discoid eczema
What other pattern of eczema is shown?
Photosensitive eczema (Note cut off at collar)
What conditions can stasis eczema occur secondary to?
- Hydrostatic pressure
- Oedema
- Red cell extravasation
What other pattern of eczema is shown?
Stasis eczema
What other pattern of eczema is shown?
Seborrhoeic eczema
What other pattern of eczema is shown?
Pompholyx eczema - Results in formation of spongiotic vesicles
What other pattern of eczema is shown?
Lichen simplexes by scratching
What are the 3 stages of eczema?
- Acute - Massive spongiosis and vesiculation
- Sub-acute - Less spongiosis with more acanthosis and scale
- Chronic - Minimal spongiosis with prominent acanthosis and scale
How will acute phase eczema present?
Acute phase will present with erythematous red lesions, oedema (Spongiosis) and ooze, scaling or crusting
How will chronic phase eczema present?
Chronic phase will lead to thickening (Lichenification), with elevated plaque formation and increased scaling
How can eczema be managed?
In most patients, emollients and topical steroids are used, with advice given on avoiding irritants such as shower gels and soaps
Phototherapy with UVB, systemic immunosuppressants and bioligic agents can also be used in more severe cases that don’t respond to steroids and emollients
