Section 1: Allergy and Immunology

Question 1

Anaphylaxis is defined as the worst form of allergic condition or acute event. It is synonymous with the term immediate hypersensitivity. The patient must
already have been sensitized to the antigen.

Describe the pathogenesis of anaphylactic reaction

Answer 1

IgE binds to mast cells, leading to the release of their granules (e.g., histamine, prostaglandins, and leukotrienes), which results in the abnormalities that essentially define anaphylaxis.

Anaphylactoid reactions are non-IgE related, are clinically identical and treated the same way, and do not need preceding sensitization to the antigen.

Presentations basically involves the Respiratory and Hemodynamic systems

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 41). Kaplan Medical Test Prep. Kindle Edition.

Question 2

True or False:

1. Anaphylaxis is defined by the severity, not the cause, of the reaction
2. Latex is a very important cause of anaphylaxis in healthcare workers
3. Urticaria is considered part of anaphylaxis, not just an allergy

Answer 2

1. True
2. True
3. True

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 41). Kaplan Medical Test Prep. Kindle Edition.

Question 3

Causes of anaphylaxis

Answer 3

1. Insect bites and stings
2. Medications:
   
   • Penicillin
   • Phenytoin
   • Lamotrigine
   • Quinidine
   • Rifampin
   • Sulfa drugs
3. Foods

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 41). Kaplan Medical Test Prep. Kindle Edition.

Question 4

CF of anaphylaxis

Answer 4

1. Hypotension, tachycardia
2. Respiratory: shortness of breath; wheezing; swelling of the lips, tongue, or face; stridor

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 41). Kaplan Medical Test Prep. Kindle Edition.

Question 5

Best initial therapy for anaphylaxis

Answer 5

• Epinephrine
• Antihistamines such as diphenhydramine (H1-blocker) and ranitidine (H2-blocker)
• Glucocorticoids such as methylprednisolone or hydrocortisone
• Emergent airway protection if needed: intubation or cricothyroidotomy

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 42). Kaplan Medical Test Prep. Kindle Edition.

Question 6

Define angioedema

Answer 6

Angioedema is sudden swelling of the:

• Face
• Tongue
• Eyes
• Airway

This can be from deficiency of C1 esterase inhibitor. There is a characteristic association with the onset with minor physical trauma

Angioedema often has an idiopathic origin

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 42). Kaplan Medical Test Prep. Kindle Edition.

Question 7

True or False:

1. There is no specific test to define anaphylaxis
2. Use of ACE infhbitors may preceed symptoms of angioedema
3. Hereditary angioedema is characterized by sudden facial swelling and stridor with the absence of pruritus and urticaria
4. Hereditary angioedema responds to glucocorticoids.

Answer 7

1. True
2. True
3. True
4. False

Question 8

Best initial test for angioedema

Answer 8

Decreased levels of C2 and C4 in the complement
pathway as well as deficiency of C1 esterase inhibitor

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 43). Kaplan Medical Test Prep. Kindle Edition.

Question 9

Outline the Rx of angioedema

Answer 9

1. Acute therapy with fresh frozen plasma or ecallantide
2. Long-term management with androgens: danazol and stanazol
3. Ensure airway protection first; can be a rapidly evolving process

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 43). Kaplan Medical Test Prep. Kindle Edition.

Question 10

Urticaria
This is a form of allergic reaction that causes sudden swelling of the superficial layers of the skin. In addition to being caused by insects and medications, urticaria can also be caused by physical agents.

List examples of physical agents causing angiodema

Answer 10

• Pressure (dermatographism)
• Cold
• Vibration

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 43). Kaplan Medical Test Prep. Kindle Edition.

Question 11

Rx for urticaria

Answer 11

1. Antihistamines:
   
   • hydroxyzine
   • diphenhydramine
   • fexofenadine
   • loratidine, or cetirizine: ranitidine
2. Leukotriene receptor antagonists: montelukast or zafirlukast

Allergic Rhinitis
Etiology
Seasonal allergies such as “hay fever” are common. This is an IgE-dependent
triggering of mast cells.
Presentation
Allergic rhinitis presents with recurrent episodes of:
· Watery eyes, sneezing, itchy nose, and itchy eyes
· Inflamed, boggy nasal mucosa
· Pale or violaceous turbinates
· Nasal polyps
Diagnostic Tests
Allergic rhinitis is most often a clinical diagnosis with recurrent episodes of
the presentation previously described. Skin testing and blood testing for reactions to antigens may be useful to identify a specific etiology. Allergen-specific
IgE levels may be elevated.
Treatment
1. Prevention with avoidance of the precipitating allergen:
· Close the windows and use air conditioning to avoid pollen.
· Get rid of animals to which the patient is allergic.
· Cover mattresses and pillows.
· Use air purifiers and dust filters.
2. Intranasal corticosteroid sprays
3. Antihistamines: loratidine, clemastine, fexofenadine, brompheniramine
4. Intranasal anticholinergic medications: ipratropium
5. Desensitization to allergens that cannot be avoided

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 44). Kaplan Medical Test Prep. Kindle Edition.

Answer 12

Treatment
1. Antihistamines: hydroxyzine, diphenhydramine, fexofenadine, loratidine,
or cetirizine: ranitidine
2. Leukotriene receptor antagonists: montelukast or zafirlukast
Allergic Rhinitis
Etiology
Seasonal allergies such as “hay fever” are common. This is an IgE-dependent
triggering of mast cells.
Presentation
Allergic rhinitis presents with recurrent episodes of:
· Watery eyes, sneezing, itchy nose, and itchy eyes
· Inflamed, boggy nasal mucosa
· Pale or violaceous turbinates
· Nasal polyps
Diagnostic Tests
Allergic rhinitis is most often a clinical diagnosis with recurrent episodes of
the presentation previously described. Skin testing and blood testing for reactions to antigens may be useful to identify a specific etiology. Allergen-specific
IgE levels may be elevated.
Treatment
1. Prevention with avoidance of the precipitating allergen:
· Close the windows and use air conditioning to avoid pollen.
· Get rid of animals to which the patient is allergic.
· Cover mattresses and pillows.
· Use air purifiers and dust filters.
2. Intranasal corticosteroid sprays
3. Antihistamines: loratidine, clemastine, fexofenadine, brompheniramine
4. Intranasal anticholinergic medications: ipratropium
5. Desensitization to allergens that cannot be avoided

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 44). Kaplan Medical Test Prep. Kindle Edition.

Answer 13

Treatment
1. Antihistamines: hydroxyzine, diphenhydramine, fexofenadine, loratidine,
or cetirizine: ranitidine
2. Leukotriene receptor antagonists: montelukast or zafirlukast
Allergic Rhinitis
Etiology
Seasonal allergies such as “hay fever” are common. This is an IgE-dependent
triggering of mast cells.
Presentation
Allergic rhinitis presents with recurrent episodes of:
· Watery eyes, sneezing, itchy nose, and itchy eyes
· Inflamed, boggy nasal mucosa
· Pale or violaceous turbinates
· Nasal polyps
Diagnostic Tests
Allergic rhinitis is most often a clinical diagnosis with recurrent episodes of
the presentation previously described. Skin testing and blood testing for reactions to antigens may be useful to identify a specific etiology. Allergen-specific
IgE levels may be elevated.
Treatment
1. Prevention with avoidance of the precipitating allergen:
· Close the windows and use air conditioning to avoid pollen.
· Get rid of animals to which the patient is allergic.
· Cover mattresses and pillows.
· Use air purifiers and dust filters.
2. Intranasal corticosteroid sprays
3. Antihistamines: loratidine, clemastine, fexofenadine, brompheniramine
4. Intranasal anticholinergic medications: ipratropium
5. Desensitization to allergens that cannot be avoided

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 44). Kaplan Medical Test Prep. Kindle Edition.

Answer 14

Treatment
1. Antihistamines: hydroxyzine, diphenhydramine, fexofenadine, loratidine,
or cetirizine: ranitidine
2. Leukotriene receptor antagonists: montelukast or zafirlukast
Allergic Rhinitis
Etiology
Seasonal allergies such as “hay fever” are common. This is an IgE-dependent
triggering of mast cells.
Presentation
Allergic rhinitis presents with recurrent episodes of:
· Watery eyes, sneezing, itchy nose, and itchy eyes
· Inflamed, boggy nasal mucosa
· Pale or violaceous turbinates
· Nasal polyps
Diagnostic Tests
Allergic rhinitis is most often a clinical diagnosis with recurrent episodes of
the presentation previously described. Skin testing and blood testing for reactions to antigens may be useful to identify a specific etiology. Allergen-specific
IgE levels may be elevated.
Treatment
1. Prevention with avoidance of the precipitating allergen:
Close the windows and use air conditioning to avoid pollen.
Get rid of animals to which the patient is allergic.
· Cover mattresses and pillows.
· Use air purifiers and dust filters.
2. Intranasal corticosteroid sprays
3. Antihistamines: loratidine, clemastine, fexofenadine, brompheniramine
4. Intranasal anticholinergic medications: ipratropium
5. Desensitization to allergens that cannot be avoided

Fischer, Conrad (2012-11-01). Master the Boards USMLE Step 2 CK (Page 44). Kaplan Medical Test Prep. Kindle Edition.