An exaggerated or inappropriate immune response caus-
What is the medical definition of hypersensitivity? ing tissue injury after antigen exposure such as an aller-
gen, medication, or infection
What immunological mechanism characterizes a Type I
IgE-mediated mast cell activation.
hypersensitivity reaction?
What is the typical timeframe for the onset of a Type I
Minutes.
hypersensitivity reaction?
List three clinical examples of Type I hypersensitivity reac-
Anaphylaxis, urticaria, and angioedema.
tions.
What is the primary mechanism of tissue injury in Type II
Antibody-mediated cytotoxicity.
hypersensitivity?
What is the expected onset timing for a Type II hypersen-
Hours to days.
sitivity reaction?
Identify two dermatologic examples of Type II hypersen-
Pemphigus vulgaris and bullous pemphigoid.
sitivity reactions.
painful lesions that rupture easily, + Nikolsky sign, has oral
Pemphigus vulgaris
lesions. ‘Risk of dehydration and secondary infection
Big tense blisters (fluid filled) and involve the basement
Bullous pemphigoid
membrane. Better prognosis. - Nikolsky sign
What is the fundamental mechanism of a Type III hyper-
Immune complex deposition.
sensitivity reaction?
What is the typical timing associated with Type III hyper-
Days.
sensitivity reactions?
Name two clinical examples of Type III hypersensitivity
Serum sickness and cutaneous vasculitis.
reactions.
What immunological mechanism defines a Type IV hyper-
T-cell mediated (delayed) response.
sensitivity reaction?
,What is the standard onset window for a Type IV hyper-
48 to 72 hours.
sensitivity reaction?
List conditions that are classified as Type IV hypersensitiv- Allergic contact dermatitis, morbilliform drug eruption,
ity reactions. SJS, TEN, DRESS, AGEP
What type of hypersensitivity reaction is morbilliform drug
Type IV.
eruption?
What is the clinical term for transient, pruritic wheals me-
Urticaria.
diated by mast cells?
Describe the classic physical appearance of an individual transient, pruritic (itchy) wheals with pale centers and
urticarial lesion. surrounding erythema.
Are hives blanchable? yes
Urticaria is common with which other symptom? Angioedema (commonly attecting the eyes and lips)
Urticaria occurs in what pattern? migration pattern, meaning they come and go
What is the maximum duration an individual urticarial
24 hours.
lesion should last before resolving?
In the pathophysiology of urticaria, what process occurs
Mast cell activation and degranulation.
after allergen cross-links IgE on mast cells?
What is the secondary step in the process of urticaria
Histamine release into the tissue.
following degranulation?
How does histamine release attect the vasculature during
It increases vascular permeability and causes vasodilation.
an urticarial reaction?
What is the end-stage dermal change that results in the Superficial dermal edema - Fluid leaks into the superficial
formation of hives? dermis, resulting in transient wheals and itching.
What is the most common etiology for urticaria? Idiopathic.
Identify two common classes of medications that trigger
NSAIDs and antibiotics.
urticaria.
, List other triggers that can induce urticaria but are not the Foods, viral infections, insect bites, and physical triggers
most common. (heat, cold, pressure).
What is the first-line pharmacologic treatment for ur- Second-generation H1 antihistamines - Cetirizine & Lo-
ticaria? ratadine
What is the recommended management step if first-line
Increase the dose (escalation).
antihistamines are insuflcient for urticaria?
When is a short course of oral steroids indicated in the
During severe flares.
management of urticaria?
Identify three systemic red flags in a patient presenting Tongue/throat swelling, dyspnea/wheezing, and hy-
with urticaria. potension.
What is the definitive treatment for urticaria when sys-
Epinephrine.
temic symptoms of anaphylaxis are present?
Define angioedema in terms of the specific skin layers
Deeper swelling of the dermis and subcutaneous tissue.
involved.
Name four anatomical sites commonly attected by an-
Lips, eyelids, tongue, and airway.
gioedema.
Which physiological mediator is typically responsible for
Histamine.
angioedema that occurs with hives?
Which physiological mediator is typically responsible for
Bradykinin.
angioedema that occurs without hives?
List four common triggers for histamine-mediated an- Foods (nuts/shellfish/eggs/milk), insect stings, medica-
gioedema. tions, and latex.
What class of antihypertensive medications is a common
ACE inhibitors.
cause of bradykinin-mediated angioedema?
Which demographic group is at a higher risk for ACE
Individuals of African descent.
inhibitor-induced angioedema?
What is the medical definition of hypersensitivity? ing tissue injury after antigen exposure such as an aller-
gen, medication, or infection
What immunological mechanism characterizes a Type I
IgE-mediated mast cell activation.
hypersensitivity reaction?
What is the typical timeframe for the onset of a Type I
Minutes.
hypersensitivity reaction?
List three clinical examples of Type I hypersensitivity reac-
Anaphylaxis, urticaria, and angioedema.
tions.
What is the primary mechanism of tissue injury in Type II
Antibody-mediated cytotoxicity.
hypersensitivity?
What is the expected onset timing for a Type II hypersen-
Hours to days.
sitivity reaction?
Identify two dermatologic examples of Type II hypersen-
Pemphigus vulgaris and bullous pemphigoid.
sitivity reactions.
painful lesions that rupture easily, + Nikolsky sign, has oral
Pemphigus vulgaris
lesions. ‘Risk of dehydration and secondary infection
Big tense blisters (fluid filled) and involve the basement
Bullous pemphigoid
membrane. Better prognosis. - Nikolsky sign
What is the fundamental mechanism of a Type III hyper-
Immune complex deposition.
sensitivity reaction?
What is the typical timing associated with Type III hyper-
Days.
sensitivity reactions?
Name two clinical examples of Type III hypersensitivity
Serum sickness and cutaneous vasculitis.
reactions.
What immunological mechanism defines a Type IV hyper-
T-cell mediated (delayed) response.
sensitivity reaction?
,What is the standard onset window for a Type IV hyper-
48 to 72 hours.
sensitivity reaction?
List conditions that are classified as Type IV hypersensitiv- Allergic contact dermatitis, morbilliform drug eruption,
ity reactions. SJS, TEN, DRESS, AGEP
What type of hypersensitivity reaction is morbilliform drug
Type IV.
eruption?
What is the clinical term for transient, pruritic wheals me-
Urticaria.
diated by mast cells?
Describe the classic physical appearance of an individual transient, pruritic (itchy) wheals with pale centers and
urticarial lesion. surrounding erythema.
Are hives blanchable? yes
Urticaria is common with which other symptom? Angioedema (commonly attecting the eyes and lips)
Urticaria occurs in what pattern? migration pattern, meaning they come and go
What is the maximum duration an individual urticarial
24 hours.
lesion should last before resolving?
In the pathophysiology of urticaria, what process occurs
Mast cell activation and degranulation.
after allergen cross-links IgE on mast cells?
What is the secondary step in the process of urticaria
Histamine release into the tissue.
following degranulation?
How does histamine release attect the vasculature during
It increases vascular permeability and causes vasodilation.
an urticarial reaction?
What is the end-stage dermal change that results in the Superficial dermal edema - Fluid leaks into the superficial
formation of hives? dermis, resulting in transient wheals and itching.
What is the most common etiology for urticaria? Idiopathic.
Identify two common classes of medications that trigger
NSAIDs and antibiotics.
urticaria.
, List other triggers that can induce urticaria but are not the Foods, viral infections, insect bites, and physical triggers
most common. (heat, cold, pressure).
What is the first-line pharmacologic treatment for ur- Second-generation H1 antihistamines - Cetirizine & Lo-
ticaria? ratadine
What is the recommended management step if first-line
Increase the dose (escalation).
antihistamines are insuflcient for urticaria?
When is a short course of oral steroids indicated in the
During severe flares.
management of urticaria?
Identify three systemic red flags in a patient presenting Tongue/throat swelling, dyspnea/wheezing, and hy-
with urticaria. potension.
What is the definitive treatment for urticaria when sys-
Epinephrine.
temic symptoms of anaphylaxis are present?
Define angioedema in terms of the specific skin layers
Deeper swelling of the dermis and subcutaneous tissue.
involved.
Name four anatomical sites commonly attected by an-
Lips, eyelids, tongue, and airway.
gioedema.
Which physiological mediator is typically responsible for
Histamine.
angioedema that occurs with hives?
Which physiological mediator is typically responsible for
Bradykinin.
angioedema that occurs without hives?
List four common triggers for histamine-mediated an- Foods (nuts/shellfish/eggs/milk), insect stings, medica-
gioedema. tions, and latex.
What class of antihypertensive medications is a common
ACE inhibitors.
cause of bradykinin-mediated angioedema?
Which demographic group is at a higher risk for ACE
Individuals of African descent.
inhibitor-induced angioedema?
