Eczema Flashcards
What is eczema?
AKA dermatitis. A pruritic papulovesicular skin reaction to endogenous or exogenous agents.
What is the pathophysiology of eczema?
Acute phase occurs from Th2-mediated sensitisation which leads to cytokine release, IgE production and peripheral eosinophilia. Persistent inflammation and scratching can lead to chronic eczema with thick, lichenified skin. Chronic eczema is more associated with Th1 immune responses.
What is the aetiology of eczema? (x3 (x3 and x6))
- Family history of atopy e.g., asthma, hay fever and rhinitis
- EXOGENOUS triggers: irritant, contact, phototoxic
- ENDOGENOUS triggers: atopic, seborrheic, pompholyx (dyshidrotic), varicose, herpeticum, discoid
What is irritant eczema?
Prolonged skin contact with a cell-damaging irritant such as ammonia in nappy rash.
What is contact eczema?
Type IV delayed hypersensitivity to allergen (cell-mediated (Th1 and APC) rather than IgE response). Allergens include nickel, chromate, perfumes, latex and plants.
What is the aetiology atopic eczema? (x2)
- Impaired epidermal barrier function due to intrinsic structural and functional skin abnormalities. For example, filaggrin mutations impair the barrier function of the epidermis. Breaks in the epidermal barrier allow increased exposure and sensitisation to antigens
- Immune function disorder in which Langerhans cells, T cells and immune effector cells modulate an inflammatory response to environmental factors
What is the pathophysiology of atopic eczema?
Mixture of Type I and Type IV hypersensitivity
What is seborrheic eczema?
Pityrosporum yeast in skin
What is varicose eczema?
Venous stasis leads to increased venous pressure in lower limbs, oedema, and RBC haemolysis which releases haemosiderin. The result is skin changes manifesting as varicose eczema.
What is discoid eczema?
AKA Nummular. It is a phenotypic description of eczema characterised by oval-shaped lesions
What is dyshidrotic eczema?
It is a phenotypic description of eczema characterised by blisters on soles of feet and palms of hand. Possible causes include contact eczema.
What is eczema herpeticum?
HSV dissemination to sites of eczema. Can be life-threatening in babies.
What is the epidemiology of eczema: Most common type? Age? Where? Family size? Socio-economic status?
Atopic eczema is most common. Presents most commonly before 5-years-old. Increased incidence in urban areas, smaller families and higher socio-economic classes.
GENERAL: What are the signs symptoms of eczema? (x3) Acute? (x4) Chronic? (x4)
- Itching and crusting, inflammation (heat, red, tenderness)
- ACUTE: poorly demarcated erythematous oedematous dry scaling patches, papules, vesicles with exudation, excoriation marks
- CHRONIC: thickened epidermis, skin lichenification, fissures, changes in pigmentation
What are the differentiating signs and symptoms of each type of eczema: Contact, Irritant, Atopic, Seborrhoeic, Pompholyx, Varicose, Discoid, Herpeticum?
- IRRITANT and CONTACT: Hx of contact with allergen/irritant. May present with autosensitisation (spread to sites other than those exposed to allergen) in contact
- ATOPIC: particularly affects face and flexures
- SEBORRHOEIC: yellow, greasy scales on erythematous plaques, particularly in the nasolabial folds (between nose and lateral corners of lips), eyebrows, scalp and sternal area
- POMPHOLYX: acute and painful vesiculobullous eruption on palms and soles
- VARICOSE: lower legs, oedema, with varicose veins
- DISCOID: coin shaped, typically on legs and trunk
- HERPETICUM: umbillicated vesicles (meaning small depressions) superimposed on atopic eczema, accompanied by fever and lymphadenopathy
