Eczema (incl. atopic, contact, discoid, dyshidrotic, herpeticum, seborrhoeic) Flashcards
Define eczema.
A pruritic papulovesicular skin reaction to endogenous or exogenous agents.
Pompholyx/dyshidrotic eczema shown on bottom right. Varicose on top right. Asteatotic eczema with “crazy paving” on the bottom left on shins.
What are the risk factors of eczema?
- Age <5 years - 45% of patients diagnosed by 6months of age and 85% by 5yrs. Early onset associated with persistance.
- FH
- M=F
- Type I skin
- Allergic rhinitis - in 50-80%. Allergen sensitisation and immune dysregulation.
- Asthma - in 40-50%
- Urban areas
- Smaller families
- Higher socio-economic class
- Anthelmintic treatment in utero
- Active and passive exposure to smoke
What is the pathophysiology of atopic eczema?
Impaired skin barrier function either acquired or inherited. Due to:
- Defect in filaggrin which is the scaffold in corneocytes +/-
- Reduced extracellular lipids + lower levels of natural moisturising factor in stratum corneum.
This means sensitisation occurs and immune dysregulation after allergen exposure. There is also transepidermal water loss.
- Acute - Th2 mediated immune response following sensitisation → IL-4, 5, 13 → more IgE production and peripheral eosinophilia
- Chronic - persistent inflammation and scratching → thick, lichenified skin. Predominantly a Th1 response and high IL-12 levels.
What is the aetiology of these types of eczema?
- Exogenous
- Endogenous
- Irritant
- Contact
- Atopic
- Seborrhoeic
- Varicose
Numerous varieties caused by a diversity of triggers.
- Exogenous: Irritant, contact, phototoxic.
- Endogenous: Atopic, seborrhoeic, pompholyx, varicose, lichen simplex.1
- Irritant: Prolonged skin contact with a cell-damaging irritant (e.g. ammonia in nappy rash).
- Contact: Type IV delayed hypersensitivity to allergen (e.g. nickel, chromate, perfumes, latex
- and plants).
-
Atopic: Two major models currently exist to explain the pathogenesis:
- 1 Impaired epidermal barrier function due to intrinsic structural and functional skin abnormalities
- (predominant model).
- 2 Immune function disorder in which Langerhans cells, T cells and immune effector cells modulate an inflammatory response to environmental factors (traditional model).
- Seborrhoeic: Pityrosporum yeast seems to have a central role.
- Varicose: Increased venous pressure in lower limbs.
How common is eczema? (atopic/contact)
Contact - prevalence 4%
Atopic - usually in first year of line, childhood incidence 10-20%
What are the types of endogenous and exogenous eczema?
What are the signs and symptoms of eczema?
- Pruritus
- Xerosis (dry skin)
-
Site
- Infants - typically cheeks, forehead, scalp and extensor surfaces (crawling); prominent weeping and crusting.
- Children - flexural (antecubital, popliteal, wrists, hands, ankles, feet). Plaques and papules with lichenificatiion from scratching.
- Chronic eczema - in addition affects neck, upper back, arms, hands and feet
- Erythema - in acute flares
- Scaling - in acute flares
- Vesicles - in acute flares and infants
- Papules in acute flares and infants
- Keratosis pilaris - hyperkeratotic papules, on extensor surfaces, arms and buttocks. Asymptomatic.
- Excoriations - in easy to reach areas
- Lichenification - thickened skin
- Hypopigmentation - affected areas will heal lighter
Describe some different clinical features of these types of eczema:
- Contact/irritant
- Atopic
- Seborrhoeic
- Pompholyx
- Varicose
- Nummular
- Asteatotic
- Contact and irritant: Eczema reaction occurs where irritant/allergen comes into contact with the skin. In some cases, autosensitization (spread to other sites) can occur in contact eczema.
- Atopic: Particularly affects face and flexures.
- Seborrhoeic: Yellow greasy scales on erythematous plaques, particularly in the nasolabial folds, eyebrows, scalp and presternal area.
- Pompholyx: Acute and often recurrent painful vesiculobullous eruption on palms and soles.
- Varicose: Eczema of lower legs, usually associated with marked varicose veins.
- Nummular: Coin shaped, on legs and trunk.
- Asteatotic: Dry, ‘crazy paring’ pattern.
What do these lesions show?
- Urticaria = raised central inflammation with flare around it
- Top = scabies (pointing to burrows) – sarcoptus scabei. Usually very quick onset.
- Middle bottom = psoriasis on extensor surfaces
- Lichen planus = shiny, flat, topped papules which are itchy. Purplish in colour. Inside wrists, ankles, back, white lines on buccal mucosa and genitals. More common in middle aged people. Fairly common. Take a punch biopsy. Treat with topical steroids. Aetiology unknown but could be linked to Hep C/medications.
What is the diagnostic criteria for atopic eczema called?
Hanifin & Rajka
What investigations would you do for eczema?
Clinical diagnosis
Other:
Contact eczema - skin patch test - disc containing postulated allergen is diluted and applied to back for 48 h. Positive if allergen induces a red raised lesion.
Atopic eczema - IgE levels; but lab testing not routinely used
Swab for infected lesions (bacteria, fungi, viruses)
What is a common symptom of discoid eczema?
It causes itching which is worse at night
What sign of eczema is shown in this child?
Dennie-Morgan folds under the eyes
A 48-year-old cleaner presented with a 1-year history of an itchy sore rash affecting both her hands. Name 3 dfferentials.
- Atopic eczema
- Psoriasis
- Contact dermatitis
- Irritant dermatitis
What is the diagnosis?
Atopic eczema = poorly defined erythematous patches on her antecubital fossae, a typical site for atopic eczema.
What has been developed for parents/carers to help with eczema management at home?
EWAP - eczema written action plant - explains how to treat eczema depending on how bad symptoms are at any given time and when to contact GP .
What is the management of atopic eczema?
- Control > cure
- Written action plan
- MDT approach
- Avoid triggers but don’t alter diet
Medical:
- Acute:
- Topical Diprobase ointment (emollient)
- Dermol 500 for washing (soap substitute)
- +/- intermittent topical Eumovate (moderate steroid) ointment
- Ongoing:
- Add topical calcineurin inhibitor
- High potency topical corticosteroid
- Resistant:
- UV (PUVA/narrow band UVB) light therapy/coal tar
- Systemic immunosuppression
- Advanced therapies
What advanced therapies are available for eczema?
- Methotrexate
- Azathioprine
- Cyclosporin
- MMF
What is this complication of atopic eczema?
Impetiginisation - gold crust due to S. aureus infection
What are the side effects of topical steroids?
Folliculitis
Worsening acne and rosacea
Infection
Perioral dermatitis
Tachyphylaxis (eczema getting worse before it gets better)
How many grams of steroid in one fingertip unit?
0.5g NB: face = 2.5 FTU needed
What are 2 side effects of topical calcineurin inhibitors?
Burning sensation
Photosensitivity - may be severe enough to cause burns in the sun
What kind of eczema does this patient have? Describe the features.
Atopic eczema is the commonest form of eczema, affecting up to 20% infants and at least 1% adults. In nearly all patients, it begins in infancy and presents with an intensely itchy rash with certain characteristics:
- Association with personal or family history of asthma, rhinitis
- Symmetrical distribution
- Flexural accentuation in childhood and adolescence
- Flare-ups
What is the diagnosis? Describe the rash.
Eczema herpeticum = due to HSV1 infection which can spread rapidly in damaged atopic eczema skin especially if topical steroids are also used.
Classically small umbilicated vesicles are seen which then deroof forming punched out erosions.
MONOMORPHIC
Name one option on each step of the steroid ladder used to treat eczema. How long can steroids me taken?
- Very potent = Dermovate
- Potent = Betnovate
- Moderate = Eumovate
- Mild = Hydrocortisone 1%
Summary of potency: 1% HC > Eumovate >Betnovate >Elocon > Dermovate
Better to “hit hard” for a few days rather than to take weak steroid for long time (so you don’t always have to start at bottom of ladder). Use for 2 days after resolution (max 5 days on face)
A lady presents with a number of very itchy lesions affecting her body but not her face. The itching is worse when warm such as in bed. No one else is affected but is persistent. What is the diagnosis?
Discoid eczema
What kind of eczema does this patient have and what are the features?
Discoid or nummular eczema can arise at any age. It often starts as a single patch at the site of injury – for example, a scratch, thermal burn, insect bite. In time, more well-defined round or oval eczematous plaques appear on limbs and trunk. Itch may be severe.
- Asymmetrical distribution
- Blistering or crusted plaques
- Relative resistance to topical steroids
What kind of eczema does this patient have and what are the features?
Dry discoid eczema is a form of asteatotic eczema and usually appears on the limbs.
- Round dry red patches
- Minimal to mild pruritus
- Response to emollients and mild topical steroids
What are the differences between contact and irritant dermatitis?
Contact = ALLERGIC CONTACT DERMATITIS - allergic reaction; T cell mediated, there may be a lag between exposure and reaction e.g. to jewellery; if affecting hands then affects PALMS
Irritant = IRRITANT CONTACT DERMATITIS - due to the direct effect of something over a long period of time; if affects hands then affects BACK of hands
What is shown?
ALLERGIC contact dermatitis - arises from direct contact with an allergen e.g. nickel in jewellery, fragrances, dyes, natural rubbers or plants like poison ivy
What are the clinical features of seborrhoeic dermatitis?
- Greasy scale, not pruritic
- Cheeks, scalp, extremities, trunk affected
- Cradle cap
- Napple area often affected
What kind of eczema does this patient have and what are the features?
Seborrhoeic eczema affects 5 to 10% adults. The infantile form usually clears by 6 to 12 months of age. Although prevalent in the scalp (dandruff), it may affect face, flexures and trunk. The main features are:
- Flaky skin
- Minimal pruritus
- Response to antifungal agents
What kind of eczema is this?
Eczema craquelé describes a crazy-paving appearance of astetatotic eczema. It is most frequently observed on the shins of middle-aged or elderly patients during the winter months.
What kind of eczema is this and what are the features?
Venous stasis eczema
- Affects the lower legs.
- Hx PAD/DVT
- Usually chronic
- UNILATERAL - rarely bilateral
- Brawny pigmentation due to haemosiderin deposition
- Chronic oedema
- Venous ulceration
- Lipodermatosclerosis (circumferential hardened skin of ankle)
What are these?
TL - dermatomyositis, usually also causes a rash on teh face and swelling of cheeks and eyelids
BL - tine corporis - fungal infection; annular lesion with pale centre and erythematous outer ring (opposite of discoid eczema)
TR - pomphlyx blisters
BR - porphyria cutanea tarda - rare disorder characterized by painful, blistering skin lesions that develop on sun-exposed skin; defect in breaking down porphyrins in blood which accumulate and cause photosensitivity. Affected skin is fragile and may peel or blister after minor trauma.
What is shown?
Pompholyx
