Dermatology >
Eczema
“An inflammatory skin condition characterised by dry, itchy skin with a chronic relapsing course. Although it can affect all ages, it is commonly diagnosed before 5 years of age”
Risk Factors
- Age <5 years
- Family history of eczema, asthma and/or allergic rhinitis
- Anthelmintic treatment in utero
- Exposure to cigarette smoke
Aetiology
- Multifactorial combination of genetic susceptibility and environmental factors
Pathophysiology
- (Type 4 hypersensitivity reaction) abnormal skin barrier function allows allergens to transverse the skin
- Allergens are taken up by antigen-present cells (APCs)
- APCs present allergen to naïve T-cell
- Naïve T-cell turns into a Th2 cell
- Th2 cell stimulates B cells to produce allergen-specific IgE antibodies
- IgE antibodies bind to mast cells and basophils, enabling sensitisation to the allergen
- Further exposure to the allergen causes degranulation
- Leading to release of histamines, leukotrienes and proteases and recruitment of eosinophils
- The skin barrier becomes leakier allowing further entry to allergen and loss of water
- Skin becomes dry and scaly
- Persistent inflammation can cause the skin to become lichenified
Clinical Presentation
- Patchy or widespread itchy, dry and cracked skin that often affects flexor surfaces (creases of wrists, insides of elbows, backs of knees) and exposed surfaces (scalp, face, hands, feet); comes in flareups; red on lighter skin/purple of grey or darker skin; hypopigmentation; lasts longer than 12 months; worst at night
Investigations
- Diagnosed clinically
Management
- Identification and avoidance of triggers, emollients, topical corticosteroids, topical calcineurin inhibitors, bandages, phototherapy
Complications
- Social stigma (depression, social anxiety)
- Limitation of everyday activities and psychosocial functioning
- Loss of sleep