Allergy Cram

Question 1

When NOT to use allergen specific IgE tests?

Answer 1

Tolerating food without IgE reaction
Food “intolerance”
Chronic idiopathic urticaria

Question 2

Contraindication to oral food challenge?

Answer 2

Skin prick test >3mm positive
ssIgE >0.35
Recent hx of reaction

Question 3

What medications to withhold pre-skin prick testing?

Answer 3

Oral antihistamines - 5 days
Some antidepressants (amitriptyline, mirtazepine) - 7 days
Antipsychotics (Quetiapine, olanzepine) - 2 weeks
Anti-emetics (chlorpromazine) - 2 weeks

Question 4

Factors influencing SPT result?

Answer 4

Recent anaphylaxis

Dermatographism

Question 5

Diagnosis of anaphylaxis?

Answer 5

Skin features - rash/erythema/flushing/angioedema
AND
resp/cardio/GI sx OR hypotension

For insect bite/stings GI sx alone is enough for anaphylaxis dx

Question 6

Risk factors for fatal anaphylaxis?

Answer 6

Adolescence
Nut/shellfish allergy
Poorly controlled asthma
Delays to treatment

Question 7

Do not let children with anaphylaxis _____

Answer 7

Stand or walk suddenly - risk of death

Question 8

Who to prescribe EpiPen to?

Answer 8

Any person with food anaphylaxis

Question 9

Type 1 hypersensitivity?

Answer 9

Immediate
IgE mediated
Anaphylaxis, urticaria, atopy

Question 10

Type 2 hypersensitivity?

Answer 10

Sub-acute
Antibody dependant cytotoxic - IgM, IgG, IgA
Haemolytic anaemia, Goodpasture, Myasthenia

Question 11

Type 3 hypersensitivity?

Answer 11

Sub-acute
Immune complex
Serum-sickness like reaction, SLE, GN, HSP

Question 12

Type 4 hypersensitivity?

Answer 12

Delayed
Cell mediated - Lymphocytes
Contact dermatitis, TENS/SJS, transplant rejection, T1DM

Question 13

Risk factors for allergic rhinitis?

Answer 13

Fix atopy
Elevated IgE by age 6
Maternal heavy smoking
Indoor allergens
LUSCS

Question 14

Risk of asthma if allergic rhinitis in childhood?

Answer 14

3 fold increase in asthma at an older age

Question 15

Pathophysiology of eczema?

Answer 15

1. Defective epidermal barrier function - allows allergens to penetrate barrier. Keratinocytes induce cutaneous immune reaction.
2. Immune dysregulation cutaneous lymphocytes increase Th2 cytokine response and IL5

Question 16

Mutation in patients with severe atopic dermatitis?

Answer 16

Filaggrin gene defect in 50%

Question 17

Severe autosomal recessive eczema with SPINK5 mutation?

Answer 17

Netherton Syndrome

Question 18

Pimecrolimus mechanism and SEs?

Answer 18

Calcinuerin inhibitor
Irritation, burning, erythema, infections/folliculitis and rarely desquamation
Can result in peri-oral dermatitis

Question 19

Difference between peri-oral dermatitis and eczema?

Answer 19

Peri-oral dermatitis has zone of sparing around lips
Rebound effect of steroids/pimecrolimus on face
Treat peri-oral dermatitis with erythromycin/tetracycline

Question 20

Super infections in eczema?

Answer 20

Staph aureus - golden crust. Mx bleach baths and PO abx
HSV - vesicles. PO antivirals
Tinea - topical antifungals
Malessezia furfural yeast

Question 21

Treatment of large local reaction to insect bite/sting? Risk of future anaphylaxis follow large local reaction to insect bites/sting?

Answer 21

PO pred, antihistamine for pruritus and NSAID for pain.

7%

Question 22

Conjunctivitis of upper tarsal surface. Exacerbations in spring/summer and itching worse with light/sweat. Long eyelashes.

Answer 22

Vernal conjunctivitis

Question 23

Conjunctivitis of lower tarsal surface with associated atopic dermatitis

Answer 23

Atopic conjunctivitis

Question 24

Conjunctivitis assoc w contact lens wear

Answer 24

Giant papillary conjunctivitis

Question 25

Urticaria VS angioedema?

Answer 25

``` Urticaria = causes swelling of dermis Angioedema = swelling of dermis, submit tissues, mucus membranes ```

Question 26

Angioedema without urticaria

Answer 26

Drug induced Hereditary C1 esterase inhibitor deficiency

Question 27

Recurrent episodes of hand/feet/genital swelling lasting a few days. Sometimes assoc w severe abdominal pain, N+V/diarrhoea. Now presents with feeling of lump in throat

Answer 27

Hereditary angioedema Cutaneous, GI, laryngeal/pharyngeal 50% at some point have laryngeal/pharyngeal involvement

Question 28

Treatment of angioedema attacks?

Answer 28

NOT responsive to adrenaline, antihistamines or glucocorticoids Recombinant/plasma derived C1 concentrate

Question 29

Rash, fever, polyarthralgia 7 days after receiving snake anti-venom/MAB therapy. Bloods show low c3/c4 and low total haemolytic complement

Answer 29

Serum Sickness

Question 30

Rash, fever, poly arthritis 2 weeks after cefaclor course.

Answer 30

Serum sickness like reaction

Question 31

4 week old baby with blood speckled stool. No FTT, vomiting or frank blood. Mo breastfeeds. Dx and Mx?

Answer 31

Allergic proctocolitis Remove trigger from diet/maternal diet if BF Usually resolves by 12mths of age - can reintroduce

Question 32

Baby with chronic, non-bloody diarrhoea after introducing cow's milk/egg/wheat. Abdo distention. Fatty stool. Bloods show anaemia and low albumin. Dx and Mx?

Answer 32

Food protein enteropathy Allergen avoidance Usually outgrown by 2-3yrs old and can re-introduce then

Question 33

Intestinal biopsy findings of food protein enteropathy?

Answer 33

Villous atrophy due to T cell activation

Question 34

Baby with vomiting, diarrhoea and hypotension after introduction of rice. Previously hospitalised for 'sepsis'.

Answer 34

FPIES

Question 35

Severe FPIES blood gas findings

Answer 35

Metabolic acidosis and methaglobinaemia

Question 36

Risk of developing atopy if FPIES in infancy?

Answer 36

30%

Question 37

When is soy formula not recommended?

Answer 37

<6mths old Higher rate of concurrent soy allergy in younger infants Nutritionally suboptimal

Question 38

Flu like sx with rash beginning on torso and spreading out. Mucosa is affected. Biopsy shows full thickness epidermal necrosis. Dx?

Answer 38

Stevens-Johnson Syndrome / Toxic Epidermal Necrolysis | Consider prednisolone/cyclosporin

Question 39

Nikolsky sign?

Answer 39

Blistering where skin is rubbed/pressure point seen in SJS/TENS

Question 40

Likelihood a child will have an topic disease when a first degree relative is affected?

Answer 40

75%