Pitfalls in patch testing

Abstract

Patch testing is an invaluable diagnostic tool in the evaluation of allergic contact dermatitis. While TrueTest has simplified the technique for many practitioners, there remains potential for error. We asked 4 experts to describe their approach to several dilemmas encountered in patch testing. Their responses will be helpful to both the veteran and tyro.

Allergic contact dermatitis

“…Pooling of data and objective comparisons are limited by the current lack of standardization, which includes the source and amount of allergens, variation in materials (chambers, vehicles), variation in the type of occlusion, the duration of application, reading times and finally the score grading of patch test reactions. antihistamines is paused while testing [31]. Finally, immunomodulators as a whole could alter the results [32] and whenever possible, they should be avoided during testing.…”

Pitfalls in patch testing

“…This is obviously not always possible. A dose lower than 20 mg a day of prednisone or 3 mg/kg/day of cyclosporine does not seem to inhibit a positive reaction [8]. On the other hand, it is always preferable not to test on skin treated with topical corticosteroids.…”

“…Antihistamines do not seem to have a clinically significant effect on patch test results. Tanning does not normally suppress significant reactions, while severe burns may suppress them; extreme tanning may interfere with interpretation of a reaction [8].…”

Vascular endothelium express CS‐1 fibronectin in allergic contact dermatitis

“…According to the mechanism of elicitation, the following types of CD may be distinguished: 1) immediate type contact reactions, 2) phototoxic and photoallergic CD, 3) irritant CD and 4) allergic CD (ACD). The clinical hallmarks, traditional and new diagnostic tools of the contact sensitivity reaction have been reviewed elsewhere 1–3 …”