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BACKGROUND:Studies assessing patch testing (PT) in allergy practices are limited. OBJECTIVES/OBJECTIVE:To determine whether PT results using a limited panel of allergens such as in the Thin-Layer Rapid-Use Epicutaneous Test (TT) as compared with an expanded panel, such as the addition of supplemental allergens (North American Contact Dermatitis [NACD] Panel, Dormer Cosmetics, hairdressing series, corticosteroid series, and personal products) will miss a significant number of positive PTs. To compare our PT results with published data from dermatology practices. METHODS:This is a 5-year multicenter retrospective chart review of PT at 3 separate allergy practices. RESULTS:Four hundred twenty-seven patients (mean age, 49.8 years) were patch tested. Eighty-two percent were female; 54% reported an atopic history. Of the standardized allergens, the 5 most common positives were nickel sulfate, fragrance mix I, p-phenylenediamine (PPD), thimerosal, and cobalt chloride. Two hundred eighteen (56.9%; 95% CI = 51.9-61.8%) patients were positive to at least 1 TT allergen. Ninety-eight (25.6%; 95% CI = 21.5-30.2%) patients were positive to both a TT and a supplemental allergen. Forty-eight (12.5%; 95% CI = 9.6-16.2%) patients were negative to a TT allergen but positive to a supplemental allergen. CONCLUSION/CONCLUSIONS:Positive allergens would have been missed in 12.5% of patients when evaluating with TT allergens alone, whereas 25.6% would be partially evaluated. Patch test performance characteristics for these allergy practices appear to parallel that seen for dermatology. The TT remains an adequate screening tool in an allergy practice, but a more comprehensive panel may be needed to fully evaluate contact dermatitis.

Although allergic contact dermatitis (CD) was previously thought to occur less frequently in patients with atopic dermatitis (AD), more recent studies show that it is at least as common in patients with AD as in the general population, if not more so. Thus, patients with AD should be considered for patch testing (PT). Although conflicting data exist, the severity of the AD may impact the PT results. Furthermore, younger patients may yield more positive PT results. Hand eczema and compositae allergy are more common in atopic patients. Reassuringly, PT is positive for topical antiseptic and corticosteroids in only a small subset of patients. When personal products are patch tested, emollients should be included in the series.

Chronic urticaria is a common disease characterized by recurrent pruritic wheals with surrounding erythema for >6 weeks. It is associated with a significant health care burden and affects patient quality of life. The etiology of chronic urticaria is often difficult to elucidate; however, known etiologies include autoimmune urticaria, physical urticarias (eg, cold, cholinergic, and delayed pressure urticaria), and idiopathic urticaria. The etiology is unknown in many patients, leading to a diagnosis of chronic idiopathic urticaria. The diagnosis of chronic idiopathic urticaria can be challenging for the primary care physician because of the disease's chronic symptoms. Diagnosis requires a detailed patient history and comprehensive physical examination, with additional testing tailored to the patient's history. Effective treatments include antihistamines, leukotriene receptor antagonists in combination with antihistamines, and oral immunomodulatory drugs, including corticosteroids, cyclosporine, dapsone, hydroxychloroquine, and sulfasalazine. Newer experimental therapies include intravenous immunoglobulin and omalizumab. This article reviews the pathophysiology, diagnosis, and treatment of chronic urticaria.

The skin is one of the largest immunologic organs and is affected by both external and internal factors, as well as innate and adaptive immune responses. Many skin disorders, such as atopic dermatitis, contact dermatitis, urticaria, angioedema, psoriasis, and autoimmune blistering disorders, are immune mediated. Most of these diseases are chronic, inflammatory, and proliferative, in which both genetic and environmental factors play important roles. These immunologic mechanisms might have implications for potential targets of future therapeutic interventions.