Mod 1 week 6 Allergies

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Are patients with atopic eczema more prone to developin allergic contact dermatitis (ACD) or irritant contact dermatitis (ICD)?
Both. Reactions more likely to occur in damaged skin or with repeated exposure e.g. ammonia - nappy rash
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% of pop with hand eczema. What % of hand eczema is caused by ICD? Is it more or less common than ACD?
5%. 25-35%. More
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Commonest site for ICD?
Hands
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Commonest site for ACD?
Face, eyelids, genitals, hands
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Types of ICD? 4
Acute, acute delayed, irritant reaction, cumulative
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Describe acute ICD pattern?
Sudden exposure to irritants like acids/alkalis -> burns with clearly demarcated margins (often linear appearance), sometimes with bullae and necrosis. Burning, stinging and soreness. e.g. jellyfish sting
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Example of acute delayed
e.g. topical retinoids causing erythema and burning a few days after use.
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Describe irritant reaction ICD
Following exposure to liquids e.g. hairdressers/metal workers at the start of their training. Starts under ring (soap gathers here and causes the problem). Spreads to dorsae of hands and fingers.
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Does ICD cause itching?
No, burning
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Describe cumulative ICD? Sx? Appearance? e.g.
Multiple subthreshold damage to the skin with inadequate gaps between insults to allow full recovery. Itching and pain. Dryness, lichenification, chapping. Asteatotic eczema.
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What is a hallmark of ICD of the hands?
Guttering - erythema of webspaces. Due to soap and detergent not being washed off adequately in people who wash hands a lot.
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Is patch testing helpful for ICD?
Yes, to exclude/identify an allergic component. NB not easy to test for irritants as direct application of irritants can cause burns.
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Management of ICD?
PREVENTION - protect skin from irritants (gloves/clothing), adequate facilities for washing. Soap substitutes. Regular emollients. Flares - topical steroids (or tacrolimus). KNMO4 soaks for pompholyx (commonly triggered by irritants)
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Advice re gloves for hand ICD?
Wear cotton gloves inside rubber/plastic gloves e.g. for washing up - keeps hands dry (otherwise can get sweaty and make things worse).
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Are barrier creams helpful in ICD if pt can't use gloves at work?
Not always - can trap irritants, enhancing effect. Sometimes develop allergy to ingredients in the cream.
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ACD - how long does sensitisation take?
4-5d
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How does sensitisation happen?
Sensitising chemical must be antigen/combine w body protein to form antigen -> penetrates S corneum -> Langerhans cells in epidermis take it up and present to T lymphs -> migrate to regional LNs -> clone of sensitised T cells reach skin of whole body
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What happens on subsequent exposure to same antigen?
Dermatitis
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Prevalence?
1-2% of general population
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Can you patch test when dermatitis active?
No, need to settle it - topical/oral steroids
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ACD o/e?
Looks like eczema in mild forms. If severe, can get whole body blistering. Hands & face common then spreads.
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What do patients find hard to grasp with ACD? How to exp[lain?
Why it affects areas not in contact with the allergen. Advise them to think of skin as a single organ - infl cascade triggered (like a lit fire), affecting the whole organ
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What is used for patch testing? How is it done?
European standard battery (ESB) of 35-38 substances. Other specialist ones available e.g. Florist series, Hairdresser series. Put into inert metal discs (Finn chambers) and attaches c micropore tape. Read at 48 and 72-96h.
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What is a positive reaction patch testing?
Papular eczema under the disc. Gets worse from day 3 to 5 (some irritant reactions look similar at day 3 but lessen by day 5)
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What patterns of eczema should raise suspicion of ACD? 7
1. Face/eyelid/perioral 2. Otitis externa 3. Hand/foot 4. Perianal/genital 5. Unusual/asymmetrical patterns 6. sudden deterioration of chronic eczema 7. certain occupations e.g. hairdresser
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Most common contact allergen?
Nickel (F>M): jewellery, jeans buttons, belt buckles, bra strap watch strap buckles, glasses frames. Gold <24 carat can be contaminated. 2005 regs limit amount of nickel that can be released from alloys. Cheap imports not always checked.
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Another common contact allergen?
Chromate - cement, plaster, leather (used in curing - causes shoe dermatitis), matches, polish, cleaners. Builders can become allergic to chromate in cement.
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Foot dermatitis - pattern (vs atopic eczema)
Usually starts DORSUM (atopic occurs on soles and sides)
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Foot dermatitis 3 most common allergens? Others?
1. Chromate 2. p-tert-Buytylphenol-formaldehyde resin (used as glue in shoes) . 3 Thiuram (used as accelerator in rubber making, included in ESB) - soles, trainers. Nail varnish, glues, fabric dyes
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Hand dermatitis - 3 potential causes?
1. ICD (powders/sweat/soap/gloves) 2. ACD (typically due to thiruam) 3. Type 1 allergy - Latex (sharp cut off of eczema at site of glove)
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Types of allergic reaction caused by latex
Type 1 (angio-oedema, anaphylaxis, urticaria, hayfever-type sx). Type 4 reactions.
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Diagnosis of latex allergy?
Skin ***** (need resus equipment) or RAST specific IgE
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Who does latex allergy affect?
HCPS, spina bifida patients or pts with indwelling catheters, atopics, women who have had multiple internal exams.
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What to advise latex allergic pts?
Avoid rubber balloons, contraceptives, swimming hats, wear rubber-free gloves (powder free hypoallergenic gloves not enough). If severe wear Medic-Alert badge and carry Epipen. Advise their dentist/doctors.
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What to consider if unilateral hand dermatitis?
Tinea
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Cause of hair dye ACD? Rx
PPD. If severe needs oral pred, dermovate, admission.
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Distribution of PPD ACD?
Spares scalp - rash is mainly on face (eyelids, face, neck). Can cause marked reddening, blistering and swelling. Dermatitis can become widespread.
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Causes of henna tattoo ACD (which chemical)? Rx
PPD. Potent topical steroids.
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Fragrance allergy - distribution? What to advise pts to look for on labels?
Anterior neck, axillae. Parfum
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Other cosmetic allergies?
Preservatives in makeup, sun blocking agents (e.g. cinnamates, bezophenones), resins in nail polish.
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Where is nail polish allergy seen?
Eyes and neck, sometimes anogenital (vapour rises to face when pt painting nails/constantly touching face/neck). Pts will rarely make the connection.
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Allergen in baby wipes?
MI (think of this with nappy rash)
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Anogenital dermatitis causes?
Allergy to components of creams e.g. LA in haemorrhoid creams, antiseptics, abx, topical steroids, preservatives in wet wipes.
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What causes ACD around eye?
Eye drops, ointments (abx, steroids, preservatives)
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What causes ACD around ears?
Ear drops/ointments. Check medicament series with patch testing (in addition to ESB)
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What causes ACD on lower legs?
Dressings, antiseptics, bandages, ointments, thiruam in rubber elasticated bandages, preservatives in emollients, lanolin in creams, fragrances.
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What to advise pts with steroid allergy? What is used as marker in patch testing?
Avoid dermovate and HC. betnovate and mometasone ok. Tixocortol pivalate.
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Plant ACD - UK cause? US?
Primula, chrysanthemum (compositae family). Poison ivy
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Distribution of primula allergy?
Hands and face - airborne (pollen). May see sharp cut off at neck where shirt collar begins.
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What is phytophotodermatitis? Rx. Cx.
Giant hogweed. Plant sap on skin -> reacts with UVB -> linear streaks and blisters. Super potent topical steroids. Post-infl hyperpig.
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2 common allergens in tattoos?
PPD in henna tattoos. Red pigment.
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Occupational dermatoses - ages affected?
2 peaks, beginning and end of working life. Atopics.
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Types of occupational dermatoses? 5
ICD. ACD. Contact urticaria - chefs handling fruit and meat - instant itching when they touch allergen. Acne - aromatic hydrocarbons - manufacture of cables. Coal tar distillation. Face, esp ears. Chemical leukoderma - depigmentation, bleaching agen
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Treatment for severe hand eczema (no responding to topicals)?
UV light, oral steroids, allitretinoin, azathioprine/cyclosporin/methotrexate
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Types of glove reaction? 3
1. Latex Advise nitryl gloves, Durex Avanti condoms. 2. Thiuram allergy (in latex, rubber). Type 4. +ve patch test. Advise vinyl gloves. 3. Irritant-gloves provide occlusive effect-sweat/water/soap
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Card 2

Front

% of pop with hand eczema. What % of hand eczema is caused by ICD? Is it more or less common than ACD?

Back

5%. 25-35%. More

Card 3

Front

Commonest site for ICD?

Back

Preview of the front of card 3

Card 4

Front

Commonest site for ACD?

Back

Preview of the front of card 4

Card 5

Front

Types of ICD? 4

Back

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