Derm + Allergy Flashcards
What is the difference between primary and secondary food allergy?
Primary (usually)
-> child failed to develop immune tolerance to antigen so in infants this is usually to COWS MILK, egg, peanut
in older adults usually to peanut, fish and shellfish
Secondary
-> where child initially tolerates it but then becomes allergic later - cross reactivity between proteins in fruit/nuts and pollen –> oral allergy syndrome
What are the symptoms of IgE and non-IgE mediated allergy?
IgE mediated allergy:
- urticaria
- facial swelling (angioedema)
- rash
- erythema
- nausea
- D+V
- colic-ky abdominal pain
- sneezing, rhinorrhoea, congestion and cough
- tightness, wheeze
- –> anaphylaxis in 10-15 mins
Non-IgE mediated:
- erythema
- atopic eczema
- GORD
- change in frequency of stools blood/mucus in stools, abdominal pain,
- FTT
- food aversion
How would you Ix suspected food allergy in a child?
Ix:
- Allergy focussed clinical history -> classify the reaction (speed, age on onset, severity, location, reproducibility/history), atopic Hx, any food avoidance, feeding history
- Test 1 = skin prick allergy testing
- Test 2 = measure specific IgE antibodies (RAST)
How would you manage food allergy?
Mx:
- Refer to specialist if faltering growth with >/=1 GI sx of allergy, >/=1 acute systemic or severe delayed reactions, multiple allergies, severe atopic eczema or persisting suspicion
- MDT - dietician advice to prevent deficiencies
- Avoid relevant foods
- Education on how to manage an allergic attack (allergy action plan!) - leaflet, explain what an allergy is, and that some children grow out of them e.g. CMPA, mild attacks use antihistamines e.g. loratadine and severe use epipen (IM adrenaline)
How can allergic rhinitis be classified and how does it present?
Intermittent vs Persistent, mild vs severe and seasonal vs perennial
Sx:
- Coryza, chronically blocked nose
- Conjunctivitis
- Sleep disturbance, impaired behaviour/concentration in day
How would you manage (Ix and Mx) allergic rhinitis?
Ix:
[Exclude other causes]
- exclude asthma or atopy symptoms/hx
- examine nose for polyps, deviated septum, mucosal swelling to depressed/widened nasal bridge
Mx:
- Occasional symptomatic relief give intranasal Azelastine at any age, or 2-5y give oral/liquid antihistamine e.g. cetrizine/loratidine as required
- Frequent symptomatic relief - avoid causative allergen and depending on the main issue give either intranasal CS (beclomethasone - nasal blockage/polyps) or intranasal CS/oral antihistamine (sneezing/discharge)
- SCIT = sub-cut immunotherapies
What is SCIT?
Specific allergen immunotherapy -> sub cutaneous immunotherapy (SCIT)
- used to treat allergic rhinitis and conjunctivitis, anaphylaxis, asthma, insect stings
- solutions of allergen are injected/sublingually introduced on a regular basis for 3-5y
- can provide years of protection but has a risk of anaphylaxis so requires specialist supervision
What is CMPA and who does it often present in?
Cows milk protein allergy can be either immediate (IgE mediated) or delayed - usually presenting in the first 3m of life in formula fed children
- common (5-15%)
- breast-fed babies can still get a reaction from proteins that mother eats but less common
How does CMPA present?
Sx (same as of food allergy)
- IgE mediated = urticaria, angioedema, rash/erythema, D&V, colicky pain, wheeze/tightness, cough and congestion –> anaphylaxis in 10-15 mins
- non-IgE mediated = erythema, atopic eczema, GORD, GI sx …
common Hx = “ 3-month old baby that vomits and has diarrhoea with every feed, failure to thrive”
How would you investigate suspected CMPA?
Ix: [same as food]
- Allergy focussed clinical history -> classify the reaction (speed, age on onset, severity, location, reproducibility/history), atopic Hx, any food avoidance, feeding history
- Test 1 = skin prick allergy testing
- Test 2 = measure specific IgE antibodies (RAST)
How would you manage CMPA (+PACES counselling!)
Mx:
- Specialist referral if multiple allergies, severe atopic eczema, >/=1 severe delayed or acute systemic reaction, faltering growth with >/=1 GI sx and persistent suspicion
1st step = trial cows milk elimination from diet for 2-6w
- -> Breast fed babies: mother excludes cows milk from her diet and consider prescribing daily 1g Ca supplement and 10mcg VitD (nb. it takes 2-3w to fully eliminate cows milk from breast milk)
- -> FF babies: replace cows milk-based formula with hypoallergenic infant formula e.g. extensively hydrolysed formula/amino acid formula (use latter if severe also)
- -> Weaned infants/older kids: exclude cows milk from diet
2nd –> regular monitoring of growth and nutritional counselling with paediatric dietician
3rd - re-evaluate tolerance to CMP every 6-12m by reintroducing the protein into the diet - if tolerance established then greater exposure of less processed milk is advised (using the ‘milk ladder’)
PACES counselling:
- Explain Dx - allergic reaction to one of the proteins in cows milk
- common, affects 5-15% of infants
- Simple treatment - just need to avoid it by either mum avoidance or using another, hypoallergenic formula
- many children grow out of it, so we will review it in 6-12m and try reintroducing milk slowly by using something called a ‘milk ladder’
- during this well also monitor his growth and get you to meet with the paediatric dieticians - advise parents to also monitor growth
- SUPPORT = British dietetic association (BDA) has a useful fact sheet - tips on avoiding products and common queries
What is Acne Vulgaris and who does it affect? What are the different levels of acne? What bacteria is involved?
Acne Vulgaris = disorder of the pilosebaceous follicles found in the face and upper trunk Affects adolescents (20% have moderate-severe) - at puberty, there is increased sebum which then blocks the glands (bacterium = propionibacterium acnes)
Levels:
- Comedones (follicles impacted and distended by incompletely desquamated keratinocytes and sebum) -> open (blackheads) or closed (whiteheads)
- Papules and pustules
- Nodulocystic and scarring
How would acne present?
Sx:
- Greasy face
- Comedones, papules, pustules, nodules
- Psychological impact, low-self esteem
How would you manage acne (12yo+)?
Mx:
- Advice -> avoid over-cleaning the skin (2x/daily with gentle soap is fine), use emollients and cleansers and non-comedogenic makeup if needed, and avoid picking and squeezing scars to reduce risk of scarring
Medications - stepwise approach (may take 8w to begin working, review each step at 8-12w)
- > Mild-Moderate acne = topical retinoid (Adapalene) +/- benzoyl peroxide (BPO) OR topical Abx (Clindamycin 1%) + BPO OR Azelaic acid 20%
- > Moderate + not responding to topicals = Oral Abx for max 3m + BPO/retinoid (use tetracylines first line, 2nd macrolides) OR COCP + BPO/retinoid
- > Dermatologist referral = oral isotretinoin (Roaccutane)
- Referred if severe form of acne (fulminant, conglobata), nodulocystic acne/scarring, severe distress psychologically, failure to respond to other medications and Dx uncertainty
- note Roaccutane is v teratogenic so must be on 2 forms of contraception, SE = dryness, pruritus, conjunctivitis, muscle aches, teratogenicity and deranged LFTs, also associated with low mood and suicide ideation (aim for accumulated dose = body weight x 100 mg)
THEN once cleared, maintain with topical retinoids or azaelic acid (20%)
support - NHS website, British association of dermatologist
What are some dermatological vascular malformations?
NOTE: these are present at birth
Naevus flammeus (‘Port wine stain’)
seen in:
- Sturge Weber syndrome flat patch –> bumpy in trigeminal nerve distribution, caused by GNAQ mutation causing intracranial lesions –> epilepsy, contralateral hemiplegia, intellectual disability
- Parks Weber syndrome
- Kippel-Trenaunay syndrome (leg/arm patch)
- Proteus syndrome
Naevus simplex (Stork’s bite/Salmon patches/Angels kiss)
- Pink/red patch at birth
- Goes redder when the infant cries
How would you Ix these vascular malformations and manage them?
Ix:
- > Clinical diagnosis
- > 1st line = USS
- > 2nd line = MRI (Sturge-Weber)
