Lack of differentiation of allergic and irritant reactions by skin autofluorescence

Diagnostic utility of skin autofluorescence when patch test results are doubtful

BACKGROUND

The standard diagnostic test for allergic contact dermatitis is the patch test, which can also be used to identify irritant contact dermatitis. Doubtful reactions (?+) can be often clinically relevant to individuals and can require additional tests.

OBJECTIVES

The purpose of this study was to examine whether autofluorescence (AF) measurements in patients with doubtful reactions are helpful in diagnosing contact dermatitis.

METHODS

Patients with a history of contact dermatitis were patch tested on the upper back for 48-hours of occlusion using aqueous solutions of 5% sodium lauryl sulfate. Reaction intensity was scored, and AF was measured on reactive lesions and non-lesions. Three dermatologists classified the results as positive or negative using the fluorescence photographs of patients with a doubtful reaction.

RESULTS

Among doubtful reactions, the R/G% values were significantly higher in the AF- based positive group than in the negative group (P = .0086). On the other hand, the heterogeneity values of R, G, and B (HR, HG, HB) were significantly lower in the AF-based positive group (P = .0026, .0046, .0004 respectively).

CONCLUSIONS

Measuring AF along with the clinical readings can help confirm doubtful patch test reactions.