Dermatitis/Psoriasis

Question 1

What is contact dermatitis? What triggers it?

Answer 1

inflammation of the skin that occurs when you come into contact with a particular substance

triggers
- irritant
= substance that directly damages the epidermis

• allergen
  = substance that triggers the immune system to respond in a way that affects the skin

Question 2

What does contact dermatitis look like?

Answer 2

skin appearance:

• red
• may appear dark brown/purple/grey in darker skin
• itchy (dominant in allergic)
• burning/stinging (dominant in irritant)
• blistered (more in allergic)
• dry and cracked
• scaly

most commonly affects hands and face especially with irritant

Question 3

What is irritant contact dermatitis? What are the different irritants that trigger it?

Answer 3

can develop from single exposure (strong irritant) or repeated exposures (weaker irritants)

usually resolves within a few days if irritant avoided

irritants:

• soaps and detergents (e.g. washing up liquid)
• perfume and cosmetics
• solvents (e.g. petrol or industrial chemicals)
• powders (soil and dust)
• plants (spurge and ranunculi)

Question 4

What is allergic contact dermatitis? What allergens trigger it?

Answer 4

usually after re-exposure to allergen
resolution can take days

allergens:

• metal jewellery (e.g. nickel)
• perfume and cosmetics (e.g. hair dyes)
• preservatives (e.g. eye drops, topical medications)
• latex
• plants (sunflowers and daffodils)

Question 5

How can contact dermatitis be treated?

Answer 5

avoid the irritant or allergen
- gloves, jewellery, health and safety at work etc.

1st Line: Emollient (same as atopic eczema)

2nd Line: Topical Corticosteroid

3rd Line : Oral Corticosteroids (severe cases)

Question 6

What is psoriasis?

Answer 6

immune-mediated, inflammatory skin disease affecting the skin, joints and nails

occurs at any age

Question 7

What causes psoriasis?

Answer 7

skin replacement process speeds up, taking just a few days to replace skin cells that usually take 21-28 days
- this abundance of skin cells builds up to form raised plaques on the skin

Question 8

What is the appearance of psoriasis?

Answer 8

skin, joints and nails affected
inflamed areas of skin

raised, red and scaly patches/plaques in appearance
- in darker skin, plaques appear purple/dark brown with grey scales and may cause post-inflammatory hyperpigmentation

scales are white/silvery
oval, irregular lesions (1-5cm diameter)

may be itchy/sore
symmetrical patches
pitted fingernails

Question 9

What are the factors increasing psoriasis flare ups?

Answer 9

influenced by inherited and environmental factors

infections 
= e.g. strep throat
hormonal changes
skin injury 
stress and anxiety
alcohol 
- altering immune function and keratinocyte activity, impairing skin barrier function
smoking 
- oxidative damage
medications – beta blockers, lithium, antimalarials

Question 10

What are differential diagnosis for psoriasis? What are associated conditions?

Answer 10

differential diagnosis:

• fungal infections
• eczema
• seborrhoeic dermatitis

associated conditions:

• psoriatic arthritis
• metabolic syndrome
• ischaemic heart disease
• IBD
• anxiety and depression
• VTE
• non-melanoma skin cancer

Question 11

How can psoriasis be managed?

Answer 11

lifestyle advice
- avoid triggers
= smoking cessation, alcohol limits, weight loss

Question 12

What are the different types of pharmacological treatments for psoriasis?

Answer 12

1st line
- topical therapy

2nd or 3rd line
- can be offered at same time if topical therapy alone unlikely to control psoriasis
= psoriasis e.g. extensive disease (≥10% BSA), moderate, nail disease where topical therapy is ineffective

Question 13

What are pharmacological treatments for psoriasis?

Answer 13

topical vitamin D preparation
= e.g. calcipotriol, calcitriol
- slows rate at which skin cells divide

coal tar preparation

• helps to remove loose scales, slows skin overgrowth
• can cause light sensitivity

dithranol

• ideal for chronic scaly psoriasis in selected areas and treatment resistant psoriasis
• slows production of skin cells
• apply sparingly, may irritate skin

salicylic acid preparations
- reduces excessive scaling for scalp psoriasis

topical retinoids
= tazarotene
- licensed for mild-moderate psoriasis

Question 14

How does phototherapy treat psoriasis? Why is it used? What type of light is used?

Answer 14

purpose is to target skin immune cells and keratinocytes, causing epidermal remodelling and reducing inflammation

duration is 8-10 weeks with 2-3 sessions per week

types of light
- Narrowband UVB
= refractory mild-moderate plaque psoriasis
= offered in preference to broad-band UVB and PUVA

• Ultraviolet A light
• before administration of UVA light, patient needs to have their skin sensitised (psoralen tablets) = PUVA

Question 15

What are drugs used for moderate-severe psoriasis?

Answer 15

methotrexate - 1st line
- slows down rapid division of skin cells and reduces inflammation

ciclosporin
- first choice if flare up or considering conception or palmoplantar pustulosis (PPP)

acitretin

• retinoid = avoid giving to women of childbearing age or PPP
• only after considering both methotrexate and ciclosporin

biologics
- monoclonal antibodies (tumour-necrosis factor-alpha inhibitors)
= e.g. infliximab, adalimumab, etanercept
- used after phototherapy when conventional systemic therapies were ineffective/not tolerated/contraindicated