Eczema/dermatitis Flashcards
What is dermaitis ?
- This refers to a group of itchy inflammatory skin conditions characterised variably by erythema, oedema, vesiculation (small fluid-filled blisters), scaling, fissuring & lichenification (thickening of skin)
- The terms dermatitis & eczema are used interchangably
Describe the histology of dermatitis/eczema in general
There is spongiosis with varying degrees of acantholysis & a superficial perivascular lympho-histocytic infiltrate
What are the different classifications of inflammatory dermatitis/eczema based on time ?
- Acute dermatitis/eczema = rapidly evolving red rash which may be blistered & swollen
- Chronic dermatitis/eczema = referring to a longstanding irritable area. It is often darker than the surrounding skin, thickened (lichenification) & scratched
What are the 2 main classifications of dermatitis/eczema ?
- Endogenous = mediated by inflammatory processes within or produced by the body
- Exogenous = mediated by inflammatory processes originating from causes outside the body
What are the main forms of endogenous eczema ?
- Atopic dermatitis
- Sebhorroeic dermatitis
- Discoid eczema (nummular dermatitis)
- Nodular purigo
- Lichen simplex chronicus
- Others
What are the main types of exogenous dermatitis/eczema ?
- Irritant contact dermatitis
- Allergic contact dermatitis
What is sebhorreic dermatitis ?
It is a chronic form of eczema/dermatitis that mainly affects the sebaceous gland rich regions of the scalp, face & trunk
What causes sebhorreic dermatitis ?
It is thought to be caused by an inflammatory reaction related to proliferation of a skin commensal called Malassezia furfur
What are the 2 forms of sebhorreic dermatitis ?
- Infatile (babies < 3months)
- Adult (tends to begin in late adolescence or the elderly)
What conditions is sebhorreic dermatitis in adults associated with ?
- HIV - if severe or widespread
- Parkinsons disease
Describe the distribution of infantile sebhorroeic dermatitis
- Commonly on the scalp as ‘cradle cap’
- Also face, neck, nappy area & limb flexures
What are the clinical features of sebhorreic dermatitis
Scalp:
- ‘Cradle cap’ = erythematous rash with scales which are yellow-brown & greasy
Elsewhere:
- well-defined areas of erythema ‘salmon-pink’ & scaling (smaller & whiter)
In infantile dermatitis the patient is usually well & itching is relatively mild/negligable
Describe the distribution of adult sebhorroeic dermatitis
Mainly affects the scalp, face (esp periorbital, nasolabial & auricular areas) & upper trunk
What are the clinical features of adult sebhorroeic dermatitis ?
- Well-defined patches of erythema with scaling & flaking of the skin
- Scales may be white/yellow or oily/dry
- Mild itch
- Scalp lesions may cause dandruff
- Ottitis externa & blepharitis may develop
How is sebhorroeic dermatitis diagnosed ?
Clinically
What is the treatment of infantile sebhorroeic dermatitis ?
For scalp:
- 1st line = topical emollient (e.g. olive/veg oil) & brush gently & wash with baby shampoo
- 2nd line = topical imidazole cream (clotrimazole 1% or miconazole)
Elsewhere:
- 1st line = bathing using emollient + barrier emollent (e.g. zinc & caster oil or parrafin ointments) + consider topical imidazole (clotrimazole 1% or miconazole)
- If nappy rash develops consider low potency TCS (hydrocortisone 1%)
What is the treatment of adult sebhorroeic dermatitis on the scalp & beard ?
- 1st line = ketonazole 2% shampoo or selenium sulphide shampoo
- 2nd line = other medicated shampoo e.g. zinc, pyrithione, coal tar, or salicylic acid
Adjunct if severe itch then add short course of TCS e.g. betatheasone valivate 0.1% or mometasone furate 0.1%
What is the treatment of adult sebhorroeic dermatitis on the face & body ?
1st line = topical anti-fungals - ketonazole 2% cream or imidazole (clotrimazole 1% or miconazole) + midly potent TCS (hydrocortisone 0.5% or 1%)
What condition may patients with sebhorroeic dermatitis develop later in life ?
Psoriasis or atopic eczema
What is discoid (nummular) eczema/dermatitis ?
An endogenous type of eczema/dermatitis in which there are scattered, roundish plaques or eczema
Note - usually plaques are less well-defined and have a finer more powdery scale than psoriasis
Who most commonly gets discoid eczema ?
- Can affect children & adults
- In males > 50 it is associated with chronic alcoholism
Describe the typical distribution of discoid eczema
Usually affects the limbs esp the legs. However, may affect trunk
What are the clinical features of discoid eczema ?
- Well-circumscribed round or oval plaques which are inflammed
- Very itchy
- May be 1. eudative = oozy papules, blisters & plaques or 2. dry = erythematous, dry plaques
- Plaques can be clear in centre ==> resembling ringworm
How is discoid eczema diagnosed/investigated?
- Diagnosed clinically
- But, skin scrappings doen to rule out tinea corporis (ringworm)
Pic shows discoid eczema presenting similar to ringworm
How is discoid eczema treated ?
Emollients + TCS (mild)
What is nodular prurigo?
- It is a skin condition characterised by very itchy firm lumps.
- It is the most severe form of prurigo (prurigo refers to intensley itchy spots)
What is the cause of nodular prurigo?
The cause if unknown. It is uncertain whether scratching leads to the nodules or if the nodules appear beforre they are scratched
Who is nodular prurigo most common in ?
- 80% of patients are atopic i.e. have asthma, eczema, hayfever or other allergic conditions
- In some it may start following an insect bite
Describe the typical distribution of nodular prurigo
The lateral aspects of the arms & legs are most commonly affected
What are the clinical features of nodular prurigo ?
- An individual nodule is a firm lump 1-3cm in diameter
- Nodule has a thick surface & may have a scab, crust or scratch marks on top of it
- Nodules are intensley itchy
- Nodules are grouped & numerous
How is nodular prurigo diagnosed?
Clinically, but if doubt do skin biopsy to confirm
How is nodular prurigo treated ?
- 1st line = emollients + ultrapotent TCS (applied under occlusion e.g. plastic cover) + oral anti-histamine e.f. fexofenadine or certirizine + phototherapy
- 2nd line = immuno-suppressive treatments - oral steroids, ciclosporin, methotrexate or azathioprine
What is lichen simplex ?
- This is a localised area of chronic, lichenified (thickened/leathery) eczema/dermatitis
- There may be single or multiple plaques