Dermatitis

• Dermatitis refers to a group of itchy inflammatory conditions characterised by epidermal changes
• Dermatitis can be classified in a variety of ways:

  • Cause e.g. allergic contact dermatitis, photosensitive dermatitis
  • Clinical appearance e.g. discoid dermatitis, hyperkeratotic dermatitis
  • Site e.g. hand dermatitis, eyelid dermatitis
• In many cases, various factors may all act together as underlying triggers together (especially in hand dermatitis):

  • Allergic
  • Irritant
  • Endogenous (e.g. atopy)
• The terms dermatitis and eczema are often used interchangeable. All eczema is a dermatitis, but not all dermatitis is eczema.

  • Dermatitis = any cause of skin inflammation affecting the epidermis
  • Eczema = oedema within the epidermis
• Different types of dermatitis are more frequent at different stages of life:

  • Children - atopic dermatitis, pityriasis alba
  • Middle aged - hand eczema
  • Middle/older age - venous eczema, nummular eczema
• Clinical features:

  • Acute - redness and/or swelling, papulation, vesiculation, oozing and weeping, and even blistering
  • Chronic - skin thickening with accentuation of the creases, hyperkeratosis, scaling, fissuring, excoriation, and hyperpigmentation
  • Subacute will show features of both
• Exogenous dermatitis is the result of an external factor:

  • Allergic contact - immune sensitisation to an allergen e.g. rubber - identified by patch testing
  • Irritant contact - anyone exposed to irritant at sufficient concentration for long enough e.g. soaps, detergents
  • Photosensitive
  • Post-traumatic dermatitis - physical injuries such as abrasions, burns
  • Induced by local skin infections
  • Drug induced
• Endogenous dermatitis is the result of internal factors:

  • Atopic dermatitis - often occurring in families with history of atopy
  • Seborrhoeic - chronic eczema affecting the face, scalp, ears and major flexures due to a reaction to yeasts that colonise the skin
  • Discoid (nummular) - coin shaped patches usually affecting the limbs
  • Lichen simplex - chronic, thickens due to perpetual scratching
  • Pityriasis alba - pale patches affecting the cheeks
• Investigations:

  • Usually history and examination is all that is required, sometimes need:
  • Skin scraping - exclude fungal infection
  • Skin swab - superimposed infection
  • Patch testing - contact allergens
  • Light testing - photosensitive dermatitis
  • Skin biopsy
  • Bloods - IgE (atopic dermatitis), thyroid function
• General management:

  • Allergen identification and avoidance
  • Irritant identification and avoidance
  • Protect skin with PPE
• Topical therapies:

  • Emollients - in place of soap, after washing, any time skin feels dry
  • Potassium permanganate soaks - dry up weepy or blistering acute eczema
  • Paste bandages - help topical steroids penetrate the skin, soothe and reduce trauma from scratching
  • Topical steroids - ointment if skin dry, cream if skin wet
  • Topical anti-inflammatory agents e.g. calcineurin inhibitors such as tacrolimus - suppress eczema and do not have the long-term side effects of potent steroids
• Topical steroids:

  • Use ointment if skin is dry, cream if skin wet and weepy
  • Most work just as well if applied once daily
  • Help reduce skin inflammation that causes eczema, and should be applied where the skin is inflamed
  • Potent products = used for 7-14 days, then reduce to alternate days, then twice weekly. Step down the potency.
  • Twice weekly steroid treatment is often recommended to prevent disease relapse
• Antihistamines are not recommended for routine use in the management of atopic eczema but if there is severe itch or urticaria:

  • Consider prescribing a month trial of a non-sedating antihistamine - cetirizine, loratadine
• Atopic eczema can be categorised by severity:

  • Mild - areas of dry skin, infrequent itching
  • Moderate - areas of dry skin, frequent itching, and redness (with our within excoriation and skin thickening)
  • Severe - widespread areas of dry skin, incessant itching, and redness (with or without excoriation, extensive skin thickening, bleeding, oozing, cracking, and alteration of pigmentation
  • Infected - weeping, crusted, pustules, with fever or malaise (usually treated with oral flucloxacillin)