Page 647 - Clinical Immunology_ Principles and Practice ( PDFDrive )

622 Part five Allergic Diseases

Symptomatic Therapy
In addition to avoidance of exposure, appropriate adjunct medical
treatment can be prescribed. First-line therapy is with topical
corticosteroids, and second-line treatment includes phototherapy,
oral retinoids, and immunosuppressant agents. The age of the
patient and the severity, location, and acuteness of the dermatitis
affect the selection of topical corticosteroids, which may be
sufficient for localized lesions. Patients with dermatitis that is
acute, extensive (particularly if involving >10% of total body
surface), or severe may benefit from systemic therapy.
Contact sensitization to the corticosteroid itself, the vehicle,
or other ingredients in the topical corticosteroid should be
suspected if symptoms worsen, initially improve but then worsen
fiG 44.6 Irritant contact dermatitis. with continued treatment, or do not respond to treatment at
all. Several topical T-cell selective inhibitors (tacrolimus and
pimecrolimus) have been used successfully in the treatment of
51
AD, but their efficacy in ACD or ICD has not been established.
tHeraPeUtiC PriNCiPLeS Other treatments, including cyclosporine, azathioprine, oral
retinoids, and phototherapy, have been used for steroid-resistant
Contact Dermatitis ACD, such as chronic hand dermatitis.
• Patch testing is the procedure of choice to confirm the diagnosis of
allergic contact dermatitis (ACD) and to identify offending contact PERSPECTIVES IN ATOPIC DERMATITIS AND
allergens.
• The interpretation of patch tests requires both experience and judgment ALLERGIC CONTACT DERMATITIS
on its relevance.
• Once identified, the key to management of ACD is prevention by Looking into the future, as we define the immune pathways that
avoiding substances containing the allergens or irritants that have cause AD, novel biologicals currently in clinical trials may provide
been identified. more targeted therapy in AD.
• Medical treatments such as topical and/or systemic corticosteroids
can be used to relieve ongoing dermatitis.
ON tHe HOriZON

• Novel biologicals currently in clinical trials may provide more targeted
Identification of the Allergen therapy in atopic dermatitis (AD).
The most widely acceptable and available method for confirming • Characterization of unique clinical phenotypes of AD may lead to a
the diagnosis of ACD is patch testing. Nickel remains the most better understanding of AD pathophysiology and a precision-medicine
approach to treatment.
common contact sensitizer and is more common in women than • Identification of “at risk” patients will facilitate preventative strategies.
in men, likely because of greater exposure to nickel in jewelry • A large number of chemicals are in everyday usage: new, rare,
and body piercing practices. In cosmetic products, fragrances, and emerging allergens should be considered in the assessment
preservatives, and emulsifiers are the most common causative of suspected ACD. Patch testing to these allergens has yet to be
allergens. In addition, paraphenylenediamine (in hair dye), standardized and irritant and elicitation concentration to patch testing
cocamidopropyl betaine (in shampoos and soaps), and medica- determined.
tions (e.g., neomycin, benzocaine, corticosteroids) are commonly • Data about contact allergen sensitization in children with AD are limited
and are continually expanding. Frequency and patterns of CD in children
reported allergens in personal hygiene and medical products. with AD and results of patch testing have yet to be determined.
The results of patch tests must be interpreted in the context of
the patient’s experience; exposure and relevance should be
established. 49
Identification of the endotypes involved in the pathogenesis
Allergen Avoidance of unique clinical phenotypes of AD will be required for a
Once the allergen or irritant has been identified, avoiding further precision-medicine approach to treatment. In the absence of a
contact with the offending agent would provide improvement low-cost cure for AD, biomarkers to identify “at-risk” patients
of the dermatitis. This requires extensive patient education on could facilitate preventative strategies.
what they are allergic to, including synonyms and cross-reactivity, In the area of ACD, a large number of chemicals are being
products they must avoid, and, most importantly, products that evaluated for their role, and new, rare, and emerging allergens
may be safe for them to use. The dimethylglyoxime test (nickel should be considered in the assessment of suspected ACD. Patch
spot test) and the cobalt spot test (based on disodium-1-nitroso- testing to these allergens has yet to be standardized; irritant and
2-naphthol-3,6-disulfonate) can be used to detect nickel or cobalt elicitation concentrations to patch testing need to be determined.
released from metal objects and dermal exposure, thus aiding Data about contact allergen sensitization in children with AD
in avoidance of contact in sensitized patients. Use of appropriate are limited but are continually expanding. Frequency and patterns
skin protection (i.e., gloves) may help with avoidance of exposure, of CD in children with AD and the results of patch testing have
especially in the occupational setting. 50 yet to be determined.