2 - Topical Contact Allergens

Question 1

Topical contact allergens induces an allergic contact dermatitis in a previously unsensitised host

Answer 1

True

Question 2

Topical contact allergens treat various dermatoses by maintaining the allergic contact dermatitis at the site of the skin disease being treated

Answer 2

True

Question 3

The ideal contact allergen is a potent contact sensitiser

Answer 3

True

Question 4

The ideal contact allergen should not be widely found in the environment

Answer 4

True

Question 5

The ideal contact allergen does not cause significant adverse effects

Answer 5

True

Question 6

The ideal contact allergen does not cross-sensitise with other substances

Answer 6

True

Question 7

It is not completely known how topical contact allergens may improve alopecia areata or viral warts

Answer 7

True

Question 8

The ‘antigenic competition’ theory has been postulated in the mechanism of action of topical contact allergens in alopecia areata, in that an immunoreaction to one antigen may inhibit the development of the immune response to another unrelated antigen

Answer 8

True (the ratio of CD4:CD8 peribulbar T cell infiltrate changes to 1:1 from 4:1 to reflect a relative increase in peribulbar CD8 T cells)

Question 9

Long term treatment of alopecia areata with topical contact allergens DPCP and SADBE leads to significant non-specific systemic suppression of delayed hypersensitivity reactions

Answer 9

True

Question 10

DPCP treatment of alopecia areata reduces the abnormal expression of Human Leukocyte Antigen (HLA) in the epithelium of lower hair follicles

Answer 10

True

Question 11

Long term treatment of alopecia areata with DPCP leads to recovery of hair follicles by driving auto reactive T cells into activation-induced cell death

Answer 11

True

Question 12

The mechanism of action of topical contact allergens in warts may be a result of a non-specific cell-mediated immune response that triggers virus-infected cell lysis and death

Answer 12

True

Question 13

Both DPCP and SADBE are non-mutagenic on the Ames test

Answer 13

True (in contrast to DNCB which is mutagenic)

Question 14

The synthetic precursor of DPCP is a potential contaminant of commercially obtained samples and a potent mutagen

Answer 14

True (although DPCP itself is not a mutagen) - presence of the contaminant may be screened before use and periodically thereafter using liquid chromatography

Question 15

DPCP is light sensitive

Answer 15

True

Question 16

DPCP’s photolysis product (diphenylacetylene) is not mutagenic

Answer 16

True

Question 17

Acetone is a standard solvent for DPCP and SADBE

Answer 17

True (acetone is a strong light absorber and dries rapidly) - DPCP is more stable in acetone than SADBE

Question 18

Women of child bearing potential should have a negative pregnancy test before starting DPCP and advised to use reliable birth control during treatment

Answer 18

True

Question 19

In alopecia areata, Eyelashes should not be treated with DPCP

Answer 19

True

Question 20

The addition of topical minoxidil did not add a significant clinical benefit in patients treated with DPCP for alopecia areata

Answer 20

True

Question 21

Fexofenadine hydrochloride can enhance the efficacy of DPCP or SADBE in alopecia areata

Answer 21

True

Question 22

Oral administration of the immunomodulatory agent inosine pranobex did not enhance the efficacy of DPCP in a patient with alopecia totalis

Answer 22

True

Question 23

Regional lymphadenopathy is a common adverse effect from topical DPCP and SADBE

Answer 23

True

Question 24

Localised contact eczema and spread of contact eczema to distant sites (autoeczematisation) are common in topical DPCP and SADBE

Answer 24

True

Question 25

Vitiligo and leukoderma are rare adverse events in topical DPCP and SADBE

Answer 25

True

Question 26

Dark skin individuals should be treated with topical DPCP and SADBE with extreme caution

Answer 26

True (rare event of vitiligo, leukoderma dyschromia of Confetti)

Question 27

Dyschromia of confetti (a pattern of hyperpigmentation and hypopigmentation) may result from topical DPCP application on treated and non-treated sites

Answer 27

True (unclear if this is a toxic or allergic reaction)

Question 28

Erythema multiforme and erythema multiforme-like eruption are uncommon adverse effects from topical DPCP

Answer 28

True

Question 29

Urticaria and contact urticaria are rare adverse effects from topical DPCP

Answer 29

True

Question 30

Topical DPCP and SADBE do not cause significant blood abnormalities

Answer 30

True

Question 31

Topical DPCP may be used in the treatment of melanoma and vitiligo

Answer 31

True

Question 32

SADBE in acetone requires refrigeration

Answer 32

True (not as stable as DPCP in acetone)

Question 33

The castling phenomenon (hair regrowth at sites distant from the site of SADBE application, or denser and faster regrowth on the untreated site than on the treated site) has been noted in alopecia areata patients treated with both topical DPCP and SADBE

Answer 33

True

Question 34

Benign lymphoplasia at the treated site may occur with topical SADBE

Answer 34

True

Question 35

DNCB is mutagenic

Answer 35

True

Question 36

> 40% of DNCB is absorbed systemically

Answer 36

True (DNCB has largely been replaced by DPCP and SADBE)

Question 37

Topical contact allergens (DPCP and DNCB) showed better results for bald areas > 50cm2 than intralesional injection of Triamcinolone Acetonide

Answer 37

True