Exaggerated triple response seen in dermatographism - red line w/in 15 sec - broadening erythema - wheel with surrounding erythema replaces red line

Urticaria Flashcards by Samantha Polly

Urticaria vs angioedema

Urticaria has edema in the superficial dermis and is well demarcated. Angioedema has edema in the deep dermis or subq and is poorly demarcated

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Ddx of urticaria

BP
DH
Drug eruption
Erythema marginatum
Erythema multiforme
Papular urticaria
Pruritic urticaria papules and plaques of pregnancy
Stills disease
Urticaria pigmentosa 
Urticaria vasculitis

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Time duration of ordinary and delayed pressure urticaria

4-36 hours

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Time duration of physical urticaria

30 minutes to 2 hr

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Time duration of contact urticaria

1-2 hrs

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Time duration of urticarial vasculitis

1-7 days

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Chronic vs. acute urticaria

6 weeks

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What are the three mechanisms for histamine release leading to acute urticaria

IgE often due to foods/drugs/inhalants
Complement/immune complex mediated often due to blood products
Nonimmunologic via drugs like aspirin and NSAIDs or histamine containing foods

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What medications exacerbate chronic urticaria

Aspirin/NSAIDs, penicillin, ACE-I, opiates, EtOH, febrille illness, and stress

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What systemic illness should you screen for in chronic urticaria

Thyroid autoimmunity, especially in females (can treat even if hypo or euthyroid)

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DDx of chronic urticaria

Cutaneous lupus, urticarial vasculitis, urticaria pigmentosa, Sweets, Fixed drug eruption, BP, Muckle-Wells (urticaria, deafness, amyloidosis), Schnitzler syndrome (nonpruritic urticaria, IgM gammopathy)

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MOA of antihistamines

Do not block the release of histamine, but inhibit its vasodilation and vessel fluid loss

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Tx options in chronic urticaria

Anti-histamines, Doxepin, steroids, Leukotriene modifiers

3rd line agents: IVIG, methotrexate, and omalizumab

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Physical urticaria subtypes

Aquagenic
Cholinergic
Cold
Delayed pressure
Dermatographism
Exercise induced
Solar
Vibratory

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Timeframe of most physical urticarias

Brief. attacks lasting 30-120 minutes

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Dariers sign

Exaggerated triple response seen in dermatographism

red line w/in 15 sec
broadening erythema
wheel with surrounding erythema replaces red line

Pressure urticaria tx

Usually required prednisone, antihistamines not as effective

Presentation of cholinergic urticaria

round papular wheels that appear after exercise

How to differentiate cholinergic urticaria from exercise induced anaphylaxis

Hot water bath with induce the urticaria without the anaphylaxis

Two types of cold urticaria

Primary (children and young adults) and secondary acquired (people with previous primary cold urticaria who develop persistent wheels with vasculitis on bx)

Solar urticaria classification

Based on wavelength that induces the urticaria

Those reacting to >400gm wavelength will get hives even through glass

Aquagenic pruritus skin findings

None, just severe prickling skin discomfort
Tx with topical capsacin
Need to r/o polycythemia rubra vera

Syndromes of Angioedema

Idiopathic recurrent
Allergic
Medication induced
Hereditary (Type I,II, and III)
Acquired (Types I and II)
Episodic angioedema with eosinophilia (benign)
Thyroid autoimmune

Hereditary antioedema substypes

Type I: C1 INH protein deficiency
Type II: C1 INH protein dysfunction
Type III: coagulation factor XII gene mutation

Acquired angioedema subtypes

Type I: lymphoproliferative dz consume C1 INH Type II: auto-immune (anti C1 INH antibody) Look for anti-C1q autoantibodies

Clinical presentation of hereditary angioedema

Late childhood or adolescence, family hx as it is autosomal dominant Recurrent non-pitting, non-pruritic, non urticarial edema

W/u of suspected hereditary angioedema

measure serum complement 4, C1-INH (inhibitor)

Treatment of hereditary angioedema

Attenuated androgens: Danazol, Stanozolol, and oxandrolone

Contact urticaria syndrome types

Immmunologic (IgE mediated, can see associated rhinitis, laryngeal edema, and GI upset, can confirm dx via RAST) Nonimmunologic (more common and benign, does not require pre-sensatization)

Pemphigoid Gestationis

self-limited, autoimmune usually presenting in late pregnancy to immediate post-partum Tx with steroids and antihistamines Associated with prematurity and small for age babies

PUPPP (pruritic urticarial papules and plaques of pregnancy)

Most common in 1st pregnancy begins in late 3rd trimester or immedicately postpartum Begins on abdomen and may spread symmetrically to extremities (initial lesions may be confined to striae) No complciations

Atopic eruption of pregnancy

``` pts with atopic background variable morphology (eczematous patches, prurigo nodules, etc) ```

Intrahepatic cholestasis

Itchy without rash (skin changes may be due to scratching) Associated with increased bile acids May recur with subsequent pregnancies Increased risk of fetal demise, prematurity, fetal distress Tx: ursodeoxycholic acid

Urticarial vasculitis clinical features

Urticaria last 1-7 days (rather than <24hrs) | Not itchy but complain of burning pain

Two subtypes of urticarial vasculitis

Normocomplement (idiopathic, benign, self-limited) and hypocomplement (more likely to have systemic sx/dz)

Serum sickness etiology

Following exposure to medication, monocloncal antibody, blood products, or animal derived vaccines Type III hypersensitivity (immune complex) reaction where these complexes get trapped in vessel walls and activate complement

Serum sickness clinical presentation

Symptoms appear 8-13 days post exposure and last for 4 days | Morbilliform rash/urticaria are classically seen with fever, malaise, arthralgias, etc

Commonly implicated drugs in serum sickness

Penicillin, sulfas, Thiouracils, aminosalicylic acid, streptomycin, hydantoins, and cholecystographic dyes