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