Allergy

Question 1

Type 1 hypersensitivity?

Answer 1

Immediate
IgE mediated - allergen binds to IgE on basophils/mast cells causing degranulation and inflammation
Anaphylaxis, Urticaria, angioedema, asthma, rhinitis

Question 2

Type 2 hypersensitivity?

Answer 2

Sub-acute
Antibody-dependant cytotoxic - IgG/M/A attacks antigen on cell surface and complement pathway activated
Haemolytic anaemia, Goodpasture, blood transfusion reaction, myasthenia, graves

Question 3

Type 3 hypersensitivity?

Answer 3

Sub-acute
Immune complex - Ag-Ab complexes deposit in tissues and activate complement/inflammation
SERUM SICKNESS LIKE REACTION
SLE, GN, HSP

Question 4

Type 4 hypersensitivity?

Answer 4

Cell mediated
Lymphocyte - cytokine release
Contact dermatitis, transplant rejection, TEN/SJS

Question 5

When is an IgE specific allergen test indicated?

Answer 5

Confirmation of IgE mediated food allergy

Determine if safe to proceed to oral food challenge

Question 6

When is IgE specific food allergen test NOT indicated?

Answer 6

If tolerating the food without an IgE reaction (eg eczema)
Food “intolerance”
Non-IgE mediated reaction (FPIES)
Chronic idiopathic urticaria

Question 7

What medication to withhold prior to skin prick testing?

Answer 7

No antihistamines for 3-5 days

No tricyclic antidepressants or antipsychotics for 7 days

Question 8

Factors influencing skin prick result?

Answer 8

Certain medications - antihistamines, amitriptyline, olanzapine
Dermatographism
Recent episode of anaphylaxis

Question 9

Positive skin prick test and positive hx?

Answer 9

Confirmation of food allergy

Question 10

Negative skin prick test and positive hx?

Answer 10

Proceed to food challenge

Question 11

What is most common use of CRD test? When not to do?

Answer 11

Peanut

Don’t do if high ARA H 2

Question 12

Definition of anaphylaxis?

Answer 12

Skin features AND resp/cardio/GI sx OR hypotension

Can still consider anaphylaxis if hx suggestive if skin features not present

Question 13

Insect bite anaphylaxis?

Answer 13

GI sx alone is sufficient for adrenaline

Question 14

Most common food allergy?

Answer 14

Egg

Question 15

Most common anaphylactic allergy?

Answer 15

Peanut, tree-nut, milk

Question 16

Risk factors for fatal anaphylaxis?

Answer 16

Adolescent age
Nut/shellfish trigger
Poorly controlled asthma
Treatment delay

Question 17

What not to do when child has anaphylaxis?

Answer 17

Let them stand or walk -> HIGH RISK OF DEATH

Question 18

Which allergens is child likely to outgrow or not outgrow?

Answer 18

Nuts and seafood - tends to persist

Egg, wheat, milk - vast majority outgrow

Question 19

Risk factors for allergic rhinitis?

Answer 19

FHx
Smokers in family
High IgE
Indoor allergens
LUSCS

Question 20

Severe allergic rhinitis?

Answer 20

Sleep disturbance or school interruption

Question 21

Prevalence of eczema?

Answer 21

10-30% worldwide; 80% outgrow by age 5

Question 22

Pathophys of eczema?

Answer 22

Defective barrier
- keratinocytes induce cytokines
- filaggrin mutation in 50% of severe eczema
- SPINK5 mutation in netherton (severe eczema syndrome)
Immune dysregulation
- Increased Th2 cytokines

Question 23

Environmental factors influencing eczema?

Answer 23

1 Environmental irritants (all pts)
2 Infections (all patients)
 - staph colonisation producing superantigen TH2 response
3 Airborne (some pts)
 - dustmites
4 Food (some pts)
 - 40% have co-existing food allergy

Question 24

Eczema treatment pillars?

Answer 24

Manage triggers
Reduce inflammation
Treat super-infections

Question 25

AEs of topical corticosteroids in eczema treatment?

Answer 25

Peri-oral dermatitis Striae if used in striae prone areas Theoretical suppression of HPA

Question 26

YEs of topical pimecrolimus in eczema?

Answer 26

Application area burning Irritation, pruritus, erythema Skin infections Desquamation (rare)

Question 27

Peri-oral dermatitis VS eczema?

Answer 27

Peri-oral dermatitis: - zone of sparing around lips - occurs as rebound following corticosteroids - treated with erythropoietin/tetracycline - is a variant of rosacea

Question 28

Treatment of large local reaction to insect bite/sting?

Answer 28

``` Cold compress Oral prednisolone NSAID for analgesia Antihistamine for pruritis RISK OF SYSTEMIC REACTION IN FUTURE IS 7% ```

Question 29

Most common conjunctivitis and is assoc w allergic rhinitis?

Answer 29

Allergic conjunctivitis?

Question 30

Conjunctivitis of upper tarsal plate, long eyelashes and worse in spring/summer?

Answer 30

Vernal conjunctivitis

Question 31

Conjunctivitis of lower tarsal plate in late adolescent with atopic dermatitis?

Answer 31

Atopic conjunctivitis

Question 32

Giant papillae in contact lens wearer?

Answer 32

Giant papillary conjunctivitis

Question 33

Serum sickness pathophysiology?

Answer 33

Type 3 hypersensitivity reaction | Ag-Ab complexes, intermediate size deposit in vessels

Question 34

Signs/symptoms of serum sickness/serum sickness like reaction?

Answer 34

Fever, rash, poly arthritis/arthralgia

Question 35

Most common drug cause of serum sickness like reaction?

Answer 35

Cefaclor

Question 36

Investigation findings in serum sickness/SSLR?

Answer 36

Low plts and neuts High ESR and CRP Urinanlysis - proteinuria, haematuria Low C3 and C4 and low total haemolytic complement (CH50)