Lecture 6: Eczema Flashcards
what is atopic eczema?
Eczema is a chronic inflammatory disorder of the skin characterised by dermal inflammation (dermatitis) with resultant spongiotic change in the epidermis histologically, with chronic features including epidermal acanthosis, hyperkeratosis, and parakeratosis.
Definition of atopic eczema using the Modified Hanifin and Rajka criteria
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 (asthma, hayfever) or in 1st degree relative if under 4 years old
what gene has a key role in eczema?
Filaggrin gene
what will histology of skin with eczema show?
- spongiosis (intercellular oedema) within epidermis
- acanthosis (thickening) of the epidermis
- inflammation - superficial perivascular lymphohistocytic infiltrate
clinical features of atopic eczema
- itchy skin
- distribution: flexures, neck, eyelids, face, hands, feet
- acute changes: pruritus, erythema, scale, papules, vesicles, exudate, crusting, excoriation
- chronic changes: lichenification, plaques, fissuring
list other types of exogenous (external) eczema
- contact dermatitis: irritant, allergic
- lichen simplex
- photoallergic or photoaggravated eczema
list some endogenous (internal) types of eczema
- atopic
- discoid
- venous
- seborrhoeic dermatitis
- pompholyx
- juvenile plantar dermatitis
- asteatotic
describe the pathophysiology of allergic contact dermatitis
- a delayed type IV hypersensitivity reaction
- exposure to allergen sensitises the immune system over time
- upon re-exposure, an immune response is triggered, leading to inflammation and the characteristic skin rash.
describe irritant contact dermatitis
- a form of contact dermatitis, in which the skin is injured by friction, environmental factors such as cold, over-exposure to water, or chemicals such as acids, alkalis, detergents and solvents.
what is thought to cause seborrhoeic dermatitis?
Malassezia Furfur, a commensal organism on the skin.
- a predisposed individual due to genetic and environmental factors may develop an inflammatory response to the organism.
Seborrhoeic dermatitis tends to affect which areas of the body?
Areas rich in sebaceous glands e.g. scalp, face, upper trunk
what is the most common term used to describe a mild, non-inflammed form of seborrheic dermatitis?
dandruff
what is the treatment for seborrheic dermatitis in adults?
anti-fungal agents such as ketoconazole shampoo
- if severe, consider HIV test
infantile seborrheic dermatitis is commonly referred to as?
cradle cap
what does discoid eczema look like?
circular plaques of eczema
describe Pompholyx eczema
- a subtype of eczema associated with intensely itchy vesicles that erupt in the hands
- it is also referred to as hishydrotic eczema
describe the appearance of asteatotic eczema
- very dry skin
- cracked scaly appearance
- most commonly shins affected
clinical features of eczema herpeticum
- disseminated viral infection
- fever and often unwell
- itchy clusters of blisters and erosions
- herpes simplex 1 and 2
- swollen lymph glands
