2 - Topical Contact Allergens Flashcards
Topical contact allergens induces an allergic contact dermatitis in a previously unsensitised host
True
Topical contact allergens treat various dermatoses by maintaining the allergic contact dermatitis at the site of the skin disease being treated
True
The ideal contact allergen is a potent contact sensitiser
True
The ideal contact allergen should not be widely found in the environment
True
The ideal contact allergen does not cause significant adverse effects
True
The ideal contact allergen does not cross-sensitise with other substances
True
It is not completely known how topical contact allergens may improve alopecia areata or viral warts
True
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
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)
Long term treatment of alopecia areata with topical contact allergens DPCP and SADBE leads to significant non-specific systemic suppression of delayed hypersensitivity reactions
True
DPCP treatment of alopecia areata reduces the abnormal expression of Human Leukocyte Antigen (HLA) in the epithelium of lower hair follicles
True
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
True
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
True
Both DPCP and SADBE are non-mutagenic on the Ames test
True (in contrast to DNCB which is mutagenic)
The synthetic precursor of DPCP is a potential contaminant of commercially obtained samples and a potent mutagen
True (although DPCP itself is not a mutagen) - presence of the contaminant may be screened before use and periodically thereafter using liquid chromatography
DPCP is light sensitive
True
DPCP’s photolysis product (diphenylacetylene) is not mutagenic
True
Acetone is a standard solvent for DPCP and SADBE
True (acetone is a strong light absorber and dries rapidly) - DPCP is more stable in acetone than SADBE
Women of child bearing potential should have a negative pregnancy test before starting DPCP and advised to use reliable birth control during treatment
True
In alopecia areata, Eyelashes should not be treated with DPCP
True
The addition of topical minoxidil did not add a significant clinical benefit in patients treated with DPCP for alopecia areata
True
Fexofenadine hydrochloride can enhance the efficacy of DPCP or SADBE in alopecia areata
True
Oral administration of the immunomodulatory agent inosine pranobex did not enhance the efficacy of DPCP in a patient with alopecia totalis
True
Regional lymphadenopathy is a common adverse effect from topical DPCP and SADBE
True
Localised contact eczema and spread of contact eczema to distant sites (autoeczematisation) are common in topical DPCP and SADBE
True
Vitiligo and leukoderma are rare adverse events in topical DPCP and SADBE
True
Dark skin individuals should be treated with topical DPCP and SADBE with extreme caution
True (rare event of vitiligo, leukoderma dyschromia of Confetti)
Dyschromia of confetti (a pattern of hyperpigmentation and hypopigmentation) may result from topical DPCP application on treated and non-treated sites
True (unclear if this is a toxic or allergic reaction)
Erythema multiforme and erythema multiforme-like eruption are uncommon adverse effects from topical DPCP
True
Urticaria and contact urticaria are rare adverse effects from topical DPCP
True
Topical DPCP and SADBE do not cause significant blood abnormalities
True
Topical DPCP may be used in the treatment of melanoma and vitiligo
True
SADBE in acetone requires refrigeration
True (not as stable as DPCP in acetone)
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
True
Benign lymphoplasia at the treated site may occur with topical SADBE
True
DNCB is mutagenic
True
> 40% of DNCB is absorbed systemically
True (DNCB has largely been replaced by DPCP and SADBE)
Topical contact allergens (DPCP and DNCB) showed better results for bald areas > 50cm2 than intralesional injection of Triamcinolone Acetonide
True
