Eczema Flashcards
What is atopic eczema?
Atopic dermatitis
Inflammatory skin condition and commonly affects flexural areas
Multiple types and spectrum of severity
Wide range of external and internal factors
Describe the pathophysiology of atopic eczema
Disrupted skin barrier
Antigens get in - dermal dendritic antigen presenting cells
T cell activated response - Th2 predominates drive
Itch and scratch cycle
What 2 things are the main aspects of eczema?
Barrier dysfunction and inflammation
What is the aetiology of eczema?
Genetics, immunology and environment
What is the definition of atopic eczema?
An itchy skin condition in the last 12 months
Plus 3 of following - onset before age 2, history of flexural involvement, dry skin and other atopic disease - asthma, hay fever or allergy
Describe the pathogenesis of eczema
Genetics - key role of Filaggrin gene and atopic family history
Epidermal barrier dysfunction
Environmental factors
Immune system dysregulation
Describe the pathology of atopic eczema
Spongiosis (intercellular oedema) within epidermis
Acanthosis (thickening of the epidermis)
Inflammation - superficial perivascular lymphohistiocyctic infiltrate
What are the clinical features of atopic eczema?
Itch
Distribution - flexures, neck, eyelids, face, hands and feet
Acute changes - pruritus, erythema, scale, papules and vesicles
Chronic changes - lichenification, plaques and fissuring
What is Danny Morgan line?
Increased eye fold in atopic eczema
What are some other types of exogenous eczema?
Contact dermatitis - irritant or allergic
Lichen simplex
Photoallergic or photo-aggravated eczema
What are some other types of endogenous eczema?
Endogenous - atopic, discoid, venous, seborrheic dermatitis, pompholyx and juvenile plantar dermatitis
Asteatosic
What is allergic contact dermatitis?
Type 4 hypersensitivity
Delayed hypersensitivity - can take 48-72hrs to develop
Describe the process of allergic contact dermatitis
Antigen presenting cells take hapten/ allergen to LN ad present to naive T cells
Clonal expansion of these T cells, released into bloodstream
When these T cells next encounter hapten - mast cell degranulation, vasodilatation and neutrophils
What is irritant contact dermatitis?
Skin injured by friction (micro-trauma or cumulative) or environmental factors (cold, over exposure to water and chemicals like acids, alkalis, detergents and solvents)
What occupation can be affected by irritant contact dermatitis?
Hairdressers, NHS staff, cleaners, nappy rash and dermatitis from soap accumulation under ring
How is allergic contact dermatitis diagnosed?
Potential allergens applied by Fin chambers
Baseline/ standard series - applied to all patients
Applied Mon, remove Wed and re-assess Fri
Describe seborrheic dermatitis - infants
Distinctive pattern
Predilection for scalp and proximal flexures - likes hair bearing sites
Under 6 months age usually
Often clears within weeks of treatment
Describe seborrheic eczema - adults
Chronic dermatitis
Malassezia yeast is increased in scaly epidermis of dandruff and seborrheic dermatitis
Red scaly marginalised lesions covered in greasy looking scales
Distinctive distribution - areas rich in sebaceous glands (scalp, face and upper trunk)
What could be a precursor for seborrheic eczema?
Dandruff
May gradually progress through redness, irritation and increased scaling
What is the treatment of seborrheic eczema?
Topical anti-yeast - ketoconazole
If severe then consider HIV test
What is discoid eczema?
Circular patches of eczema
Often the cause is unknown
May develop at sites of trauma/ irritation
Describe pompholyx/ vesicular eczema
Palms and soles
Intensely itchy
More common under 40
Sudden onset of crops of vesicles
Resolution can include desquamation
Describe asteatotic eczema
Very dry skin and cracked scaly appearance
Most commonly skins affected
Climate - heat
Excessive washing/ soaps
Describe venous eczema
Stasis eczema or varicose eczema
Increased venous pressure
Oedema
Ankle and lower leg involved
Resolution of oedema can help - compression stockings
