Transcript Allergy/ Immunology Board Review

Allergy/ Immunology
Board Review
December 17, 2007
Overview of Topics
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Allergic Reactions Types 1-4
Systemic Anaphylaxis
Stings
Allergic Reactions to Foods, Contrast and Latex
Serum Sickness
Allergy Testing
Therapy
Medications
Immunotherapy
Physical Exam Findings
Allergic and Vernal Conjunctivitis
Allergic Reactions
Types 1-4
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Type 1 IgE Mediated Anaphylactic Reaction
Examples: Allergic Rhinitis, Urticaria
Type 2 Mediated by Antibodies
Examples: Autoimmune Hemolytic Anemia, Rh and
ABO Incompatibility
Type 3 Immune Complex
Examples: Serum Sickness, Immune Complex
Mediated Renal Diseases
Type 4 Delayed Hypersensitivity
Examples: Poison Ivy, PPD Reactions
Urticaria
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Well circumscribed,
raised, palpable wheals
that blanch with applied
pressure
Usually erythematous but
may be pale or white
with red halos
Allergic Rhinitis
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Eosinophilic Inflammation of Nasal Mucosa
Look for transverse nasal crease on physical exam
Eosinophils will be present in nasal secretions
Non-allergic rhinitis can be:
Vasomotor rhinitis -presents with congestion,
rhinnorhea and post nasal drainage unrelated to any
trigger or infectious agent.
Infectious rhinosinusitis -younger children worse in the
winter
Foreign body
Allergic Rhinitis Medications
Mild: Antihistamine prn or routine in season
 Moderate: Routine administration or
Leukotriene Receptor Antagonist (LTRA)
If poor response topical nasal steroid. If needed
most of the year add immunotherapy.
 Severe: Topical nasal steroid, Immunotherapy,
Antihistamine or LTRA, Rarely Brief oral
Corticosteroid
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Systemic Anaphylaxis
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Due to widespread degranulation of mast cells
after crosslinking of IgE on the mast cell
surface.
Rapid. Often after bee stings, food exposure, or
drug administration.
Severe Manifestations: Airway obstruction and
hypotension
Other signs: Urticaria, Angioedema
Stings
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Treatment: Children younger than
16 with diffuse urticaria require
epinephrine.
Children >16 are treated as adults
and require subcutaneous epi.
Any child with a systemic reaction
to a bee sting requires referral to an
allergist.
Any child with a life threatening
reaction to a bee sting requires
venom immunotherapy which is
98% effective in preventing future
reactions.
Food Allergy
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Immune Mediated
Reactions
IgE Mediated
(Hypersensitivity)—
Symptoms: Shortly after
exposure
Skin, Respiratory or GI
manifestations
Symptoms >2 hrs post
exposure uncommon
Food Allergy Anaphylaxis
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Severe systemic reaction not uncommon
Asthmatics with peanut allergy are the highest
risk group.
Likeliest allergens:
Infants and toddlers: Egg, Peanut, Milk
Older kids: Peanut, Nut, Fish, Shellfish
Therapy: Education—Avoidance
Emergency Planning– Epi Pen and a plan
Serum Sickness
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Circulating complexes of antibody and antigen
Prior exposure not necessary
Due to fairly persistent drug or hapten
If severe steroids should suppress symptoms
Classically associated with animal sera (diphtheria)
Modern settings: Anti-venom for snake bites, Nonhumanized monoclonal antibodies
Anaphylaxis Therapy
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Epinephrine is primary
Antihistamines are secondary
For severe event steroids may prevent late phase
reaction.
Angioedema
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Hereditary Angioedema:
Autosomal Dominant
Disorder characterized by the
absence or abnormal
function of the C1 Esterase
Inhibitor which results in
increased vascular
permeability.
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Angioedema related to
allergic reaction: Self limiting,
episodic, commonly triggered
by minor trauma.
Allergic Reaction to Contrast Media
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Contrast reactions are not IgE mediated. They
are an osmolality hypertonicity reaction that
triggers degranulation of mast cells and
basophils with release of mediators that then
cause the reactions.
Latex Allergy
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Significant problem in 80s 90s due to increased
latex exposure with universal precautions.
Pediatric high risk groups: Spina Bifida >40%
Any child with repeated surgery early in life
Common Indoor and Outdoor
Allergens
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Indoor: Cat, Dog, Dust Mites, Cockroach, Molds
Outdoor: Pollens, Molds
 Seasonality-Spring: Trees, Some Molds
Summer: Grasses, Molds, Weeds
Late Summer: Ragweed, Mold
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Skin Testing
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Useful to diagnose Type I Hypersensitivity Reactions
In vivo method to detect the presence of IgE
antibodies to specific allergens.
Test interpreted by measuring the maximum diameter
of the wheal and the flare and by comparison with
control site.
Contraindications: recent antihistamine use, skin disease
in testing area, during asthma exacerbation or episode
of anaphylaxis, if taking B blocker
RAST
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RAST is done in vitro.
Is not impacted by antihistamine treatment like
skin testing
No risk for anaphylactic reaction unlike skin
testing
Allergy Therapy
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Avoidance of Allergen
Medication
Allergen Immunotherapy
Anti-IgE
Prevention of Sensitization
Allergy Medications
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Antihistamines
1st generation: sedation problems
2nd generation: preferred where sedation a problem
Leukotriene receptor antagonists (LTRA)
Similar efficacy to antihistamines
Mast Cell Stabilizers
Topical Corticosteroids
Most effective, block more aspects of allergic
inflammatory response
Allergy Immunotherapy
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Proven benefit for allergic rhinitis
Mixed studies with asthma
Not indicated for atopic dermatitis
Not indicated for food allergy
Allergy-Physical Exam
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Eyes: Dennie-Morgan
(infra-orbital pleats),
Infra-orbital (allergic)
shiners
Nose: Boggy mucosa and
airway impairment,
Transverse nasal crease
Throat/Mouth:
Overbite, Lymphoid
Cobblestoning of
posterior pharyngeal wall
Lungs: Wheezing
Skin: Eczema
Ocular Allergies
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My involve eyelid or conjunctiva
Occur when exposed to triggering agent
Allergic Conjunctivitis
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Allergic Conjunctivitis
Acute or Chronic,
Seasonal or Perennial
Itching and Excessive
tearing
Physical Finding: Allergic
Cobblestoning with fine
granular appearance of
the conjunctiva
Vernal Conjunctivitis
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Uncommon and Chronic
Mostly in young atopic boys
Symptoms: Severe itching,
photophobia, blurring of
vision, and tearing
Physical Exam Finding:
White, Ropy secretions that
contain many eosinophils,
may see hypertrophic nodular
papillae that resembles
cobblestones usually on the
upper eyelid.
May be due to build up on
foreign objects being placed
in the eyes such as contacts
for long durations with
chronic exposure