Contact Allergy: alternatives for the 2007 North American contact dermatitis group (NACDG) Standard Screening Tray.

ost primary care physicians see a large number of patients each year ith eczematous skin diseases. Although many of these patients have topic eczema, another extremely common cause of eczema is contact llergy. This subgroup of eczema patients is notably resistant to treatment nless the causative allergens can be identified and eliminated. It is stimated that allergic contact dermatitis (ACD) to topical products alone ccurs in 1% to 3% of the general population. Unlike respiratory and ood allergies, ACD is not histamine-mediated but is instead a T-cellediated delayed-type hypersensitivity reaction. The basic pathophysilogic process behind ACD is primary skin contact with an allergenic hemical which triggers an immune cascade and results in an eczematous eaction at the site of contact. On first exposure to low molecular weight chemical substances (haptens 500 Da), there is generally no skin reaction. During this first phase, hese haptens enter the epidermis and are recognized by antigen presentng cells, which in turn create signals that transform naïve T cells into emory T cells, a process which typically takes 5 to 25 days. ubsequent reactions due to “challenge” with the same chemical subtance generally occur between 24 and 48 hours after exposure; however, eports of reactions occurring as early as 8 hours after exposure and as ong as 1 week after exposure are not uncommon.