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Allergy/ Immunology Board Review

Allergy/ Immunology Board Review. December 17, 2007. Overview of Topics. 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

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Allergy/ Immunology Board Review

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  1. Allergy/ ImmunologyBoard Review December 17, 2007

  2. Overview of Topics • 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

  3. Allergic ReactionsTypes 1-4 • 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

  4. Well circumscribed, raised, palpable wheals that blanch with applied pressure Usually erythematous but may be pale or white with red halos Urticaria

  5. Allergic Rhinitis • 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

  6. 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

  7. Systemic Anaphylaxis • 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

  8. 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. Stings

  9. Immune Mediated Reactions IgE Mediated (Hypersensitivity)— Symptoms: Shortly after exposure Skin, Respiratory or GI manifestations Symptoms >2 hrs post exposure uncommon Food Allergy

  10. Food Allergy Anaphylaxis • 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

  11. Serum Sickness • 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, Non-humanized monoclonal antibodies

  12. Anaphylaxis Therapy • Epinephrine is primary • Antihistamines are secondary • For severe event steroids may prevent late phase reaction.

  13. Hereditary Angioedema: Autosomal Dominant Disorder characterized by the absence or abnormal function of the C1 Esterase Inhibitor which results in increased vascular permeability. Angioedema related to allergic reaction: Self limiting, episodic, commonly triggered by minor trauma. Angioedema

  14. Allergic Reaction to Contrast Media • 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.

  15. Latex Allergy • 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

  16. Common Indoor and Outdoor Allergens • Indoor: Cat, Dog, Dust Mites, Cockroach, Molds • Outdoor: Pollens, Molds • Seasonality-- Spring: Trees, Some Molds Summer: Grasses, Molds, Weeds Late Summer: Ragweed, Mold

  17. Skin Testing • 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

  18. RAST • RAST is done in vitro. • Is not impacted by antihistamine treatment like skin testing • No risk for anaphylactic reaction unlike skin testing

  19. Allergy Therapy • Avoidance of Allergen • Medication • Allergen Immunotherapy • Anti-IgE • Prevention of Sensitization

  20. Allergy Medications • 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

  21. Allergy Immunotherapy • Proven benefit for allergic rhinitis • Mixed studies with asthma • Not indicated for atopic dermatitis • Not indicated for food allergy

  22. 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 Allergy-Physical Exam

  23. Ocular Allergies • My involve eyelid or conjunctiva • Occur when exposed to triggering agent

  24. Allergic Conjunctivitis Acute or Chronic, Seasonal or Perennial Itching and Excessive tearing Physical Finding: Allergic Cobblestoning with fine granular appearance of the conjunctiva Allergic Conjunctivitis

  25. 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 Vernal Conjunctivitis

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