The role of patch testing for chemical and protein allergens in atopic dermatitis

Atopy and Sensitization to Allergens Known to Cause Systemic Contact Dermatitis

BACKGROUND

Atopic dermatitis (AD) associated with respiratory atopy may represent a form of systemic contact dermatitis (SCD), whereby AD flares after ingestion or inhalation of allergens.

OBJECTIVE

The aim of the study was to compare the prevalence of positive patch tests to allergens known to cause SCD in AD patients with and without respiratory atopy.

METHODS

This is a retrospective study of patients with AD patch tested to 23 allergens known to cause SCD. Positive patch tests were compared between AD patients with and without respiratory atopy, stratified by age and wet or dry work occupation.

CONCLUSIONS

Children and adolescents, but not adults, with AD and respiratory atopy were more likely than age-matched AD patients without respiratory atopy to have positive patch tests to these allergens (odds ratio, 2.33; 95% confidence interval, 1.13-4.79). Moreover, AD patients with respiratory atopy and engaging in wet work, but not dry work, occupations were more likely than AD patients without respiratory atopy to have positive patch tests to allergens known to cause SCD (odds ratio, 1.47; 95% confidence interval, 1.05-2.06). Thus, respiratory atopy and wet work are associated with sensitization to allergens known to cause SCD in patients with AD, and patch testing may be valuable in identifying systemic triggers of dermatitis in these patients.

Relationship between the atopy patch test and clinical expression of the disease in children with atopic eczema/dermatitis syndrome and respiratory symptoms

BACKGROUND

The atopy patch test (APT) may be the only positive skin test result in patients with either atopic eczema/ dermatitis syndrome (AEDS) or respiratory abnormalities with or without AEDS.

OBJECTIVE

To investigate the possible significance of APT to dust mite by comparing the positive result to this test with that of the skin prick test (SPT) in patients with different characteristics.

METHODS

A total of 297 individuals (178 boys and 119 girls) aged 5 to 221 months (mean [SD] age, 64.5 [42.1] months; median age, 58 months) were included in this study. Participants were divided into 4 groups: current AEDS, current AEDS and respiratory symptoms, past AEDS and respiratory symptoms, and respiratory symptoms with neither current nor past AEDS (control group). All the patients underwent SPT and APT using house dust mite extract.

RESULTS

In the study groups, the rate of positivity was significantly higher for APT, whereas in the control group, there were significantly more positive results to SPT (P < .001 for both). Multivariate analysis showed that there was a high probability of a positive APT result in patients with AEDS (odds ratio [OR], 17.4), with AEDS and respiratory disease (OR, 21.9), and with past AEDS and respiratory disease (OR, 22.8).

CONCLUSIONS

These patients with AEDS showed 2 different patterns of allergic response to allergens, one IgE mediated (as evaluated by positive SPT results) and the other cell mediated (as evaluated by positive APT results). The former seems to follow the so-called atopic march model, and the latter persists even after the disappearance of AEDS and is likely to be implicated in the pathogenesis of respiratory allergy.

Eyelid dermatitis

Cosmetic alteration of a patient's orbital skin is a common reason for professional consultation. This review presents the differential diagnosis and recommended evaluation of inflamed eyelids. To better understand the diseases, each is individually addressed clinically, pathogenetically, and therapeutically. It is critical to recognize the lesions correctly and to have full knowledge of the putative clinical disease process. An algorithm for an appropriate work-up for each disease is offered. With this background, a successful therapeutic response can be anticipated.