Chapter 4: Contact Dermatitis and Patch Testing

Question 1

What is contact dermatitis

Answer 1

And eczematous dermatitis caused by exposure to substances in the environment

– May cause acute, subacute, or chronic eczematous inflammation

Question 2

What is the most common cause of contact dermatitis

Answer 2

Irritation of the skin

– Repeated use of strong alkaline soap or industrial exposure to organic solvents extract lipids from the skin.

Question 3

How do you manage irritant contact dermatitis

Answer 3

1. Avoid exposure to irritants
2. Topical steroids are used initially
3. Moisturizers used generously and frequently
4. Barrier creams
5. Cold compresses a use for acute inflammation.
6. Hands should be washed in cool or tepid water
7. Repeated low-level UV exposure may be effective for long-term persistent cases.
8. Even after the skin appears normal it takes approximate four months or more for barrier function to normalize

Question 4

What are the two phases associated with allergic contact dermatitis

Answer 4

1. Sensitization phase

2. Elicitation phase

Question 5

What is the sensitization phase of allergic contact dermatitis

Answer 5

Antigen is applied to the skin surface, penetrates the epidermal barrier, it is taken up by the Langerhans cells in the epidermal basal layer
– the Langerhans cell migrates to the regional lymph nodes and presents the antigen to the T lymphocyte.

Question 6

What is the elicitation phase of allergic contact dermatitis

Answer 6

Occurs in sensitized patients with re-exposure to the antigen.

– This interaction results in cytokine induced activation and proliferation of the antigen specific T lymphocytes and the release of inflammatory mediators

Question 7

What is cross sensitization

Answer 7

An allergen, the chemical structure of which is similar to that of the original sensitizing antigen, may cause inflammation because the immune system is unable to differentiate between the original and the chemically related antigen

Question 8

What is systemic contact dermatitis

Answer 8

Results from the exposure to an allergen by ingestion, inhalation, ingestion or percutaneous penetration in a person previously sensitized to the allergen by cutaneous contact

Question 9

What is the most important clue to the cause of an allergen

Answer 9

The shape and location of the rash

– The scalp, palms, and soles are resistant to allergic contact dermatitis and may show only minimal inflammation despite contact with an allergen that produces dermatitis and adjacent areas.

Question 10

The failure of an eczematous dermatitis to respond to standard treatments suggest what

Answer 10

Suggests that the dermatitis is allergic and not irritant

Question 11

How can you determine the intensity of the inflammation and degree of sensitivity

Answer 11

The location and duration of inflammation

– Acute inflammation appears as macular erythema, edema, vesicles, bullae

– Chronic inflammation is characterized by lichenification, scaling, or fissures.

Question 12

How prevalent is allergic contact dermatitis in children

Answer 12

Allergic contact dermatitis may account for as many as 20% of all cases of dermatitis in children

Question 13

What is the management of allergic contact dermatitis

Answer 13

1. Minimize products for topical use.
2. Use ointments instead of creams (creams contain preservatives and are complex mixtures of chemicals)
3. Botanical extracts may be used in “fragrance free” products
4. When patch testing, also test the patient’s consumer products.
5. Read product labels carefully.

Question 14

What is rhus dermatitis

Answer 14

Allergens responsible for poison ivy and poison oak allergic contact dermatitis are contained within the resinous sap material terms urushiol

urushiol is composed of a mixture of catechols

Question 15

What are the characteristic lesions of a rhusdermatitis

Answer 15

Linear lesions created when part of the plant is drawn across the skin or from streaking the oleoresin while scratching

– Quickly as eight hours after contact or may be delayed for one week or more

Question 16

Do blister fluids contain the oleoresin and a rhusdermatitis

Answer 16

No, furthermore blistered Fluid can not spread the inflammation

Question 17

What can be done to prevent the spread of a rhusdermatitis

Answer 17

Washing the skin with any type of soap and inactivates and removes all surface oleoresin

After 10 minutes, only 50% of the urushiol can be removed; after 30 minutes, only 10% can be removed; and after 60 minutes none can be removed

Question 18

What is the treatment of acute inflammation with rhus dermatitis?

Answer 18

blisters and intense erythema are treated with cold, wet compresses, and they are highly effective during the acute blistering stage.

Calamine lotion controls itching but prolonged use causes excessive drying.

Question 19

How is severe poison ivy treated

Answer 19

Prednisone, administered in a dosage of 20 mg twice each day for at least seven days

Question 20

What are the three types of reactions to natural rubber latex (NRL)

Answer 20

irritant contact dermatitis

Allergic contact dermatitis

immediate-type hypersensitivity reaction

Question 21

What is irritant contact dermatitis from natural rubber latex

Answer 21

A non immune eczematous reaction caused by moisture, heat, and friction under gloves

Question 22

What is allergic contact dermatitis (type IV hypersensitivity)

Answer 22

Latex allergy occurs in up to 10% of operating room nurses.

Delayed type hypersensitivity (type IV) is a T-cell-mediated sensitization to rubber accelerators and antioxidants and latex gloves causes an allergic contact dermatitis usually limited to the sites of the direct contact

-Once sensitized, subsequent challenges from the same allergen will cause eczematous dermatitis.

Type IV allergy accounts for about 80% of occupationally acquired rubber allergy.

Question 23

What is immediate-type hypersensitivity (type I allergy)

Answer 23

IgE mediated reaction requires previous sensitization.

Skin skin exposure causes contact urticaria

Exposure to latex in the air elicits allergic rhinitis, conjunctivitis, asthma, anaphylaxis, and death

Question 24

Patients with type I NRL allergy can have a cross reaction to certain foods; what are the foods

Answer 24

Banana
avocado
tomato
Kiwi

Or local irritation when working with such food

Question 25

What is the RAST test

Answer 25

Used to detect specific IgE, such as those with the latex specific allergy

Question 26

If the patient does not respond to treatment for dermatitis or should be the next step in consideration

Answer 26

Treatment should be patch test to exclude allergy

Question 27

What is the leading cause of allergic contact dermatitis worldwide

Answer 27

Sensitization to nickel

Question 28

Just cooking with stainless steel pans provide a source of nickel ingestion

Answer 28

Nope

Question 29

What is baboon syndrome

Answer 29

Intertriginous drug eruptions

Symmetric eczematous eruptions involving the elbows, axilla, eyelids, and sides of the neck accompanied by bright red anogenital lesions.

Question 30

What is the most common synthesizer for men in industrialized countries

Answer 30

Chromate

Sources are cemented, photographic processes, metal and dyes

Question 31

What is cement dermatitis

Answer 31

Severe deep cutaneous alkaline (pH 12) Burns may occur in the lower legs of men whose skin is in direct contact with wet cement.

Question 32

What is the most common cosmetic allergen

Answer 32

Fragrance

Question 33

Is it possible to be allergic to topical steroids

Answer 33

Yes

Question 34

When is patch testing warranted

Answer 34

Cases in which inflammation persist despite avoidance of the offending agent and appropriate topical therapy.

Question 35

What is an open patch test

Answer 35

The suspected allergen is applied to the skin of the upper outer arm and left uncovered. Application is repeated twice daily for two days

Question 36

What is the use patch test

Answer 36

Suspected cream or cosmetic is used on a site distant from the original eruption.
the material is applied twice daily for at least seven days. The test is stopped if a reaction occurs

Question 37

What is a closed patch test

Answer 37

the material is applied to the skin and covered with adhesive bandage. The adhesive bandage is removed in48 hours for the initial interpretation

A negative patch test with this direct technique does not rule out the diagnosis of allergy

Question 38

How’s a patch test graded

Answer 38

Test reactions are graded:
\+ = weak (nonvesicular)
\+ + = strong (edematous or vesicular)
\+ + + = extreme (spreading, bolus, ulcerative)
- = negative reaction
IR - irritant reaction

Question 39

What is the concern with using steroids with patch testing

Answer 39

Corticosteroids such as prednisone in dosages of 15 mg per day or the equivalent may inhibit patch test reaction.

If a patient has been treated with systemic corticosteroids, patch testing should be delayed for at least two weeks

Question 40

What is excited skin syndrome

Answer 40

(Eczema creates eczema)

Excited skin syndrome is a major cause of false-positive patch test reactions.