Contact allergy patch testing

Local problems can occur, including hypersensitivity reactions (1). In one case of contact allergy, patch-testing was positive with clotrimazole (5% in petroleum), itraconazole (1% in ether), and croconazole (1% in ether) (7). The authors reviewed the possible cross-reactions between the subgroups of imidazoles. 

Reports of contact allergy to topical medicaments containing sodium metabisulfite are rare (9). In two cases, a topical corticosteroid formulation that contained sodium metabisulfite (Trimovate cream) caused contact allergy patch tests were positive with both sodium metabisulfite and Trimovate cream (10). 

True IgE-mediated anaphylactic reactions to LAs are extremely rare [11-13]. Only single cases have been reported in the literature with positive prick tests [ 14,15]. A case of a positive open patch test in a patient suffering from contact urticaria after topical application of lidocaine, pilocaine mixture (Emla cream) might represent a true IgE-mediated allergy [16]. The maj ority of immediate-type reactions are non-immune in nature. 

Breit S, Rueff F, PrzybiUa B Deep impact contact allergy after subcutaneous injection of local anesthetics. Contact Dermatitis 2001 45 296-297. Orasch CE, Helbling A, Zanni MP, Yawalkar N. Hari Y Pichler WJ T-cell reaction to local anaesthetics relationship to angioedema and urticaria after subcutaneous application-patch testing and LTT in patients with adverse reaction to local anaesthetics. Clin Exp Allergy 1999 29 1549-1554. 

A retrospective study was performed of 3851 patients who presented at a clinic with suspected allergic contact dermatitis over a 5-year period. Workup of each case included standard patch tests for delayed-type sensitivity. Of the 3851 patients, 145 had type IV allergies to one or more rubber constituents. Five of the 145 were positive to MBT. 

A 57-year old Caucasian man with inflammatory bowel disease was given prednisolone metasulfobenzoate sodium enemas twice daily and oral mesalazine 800 mg tds for about 5 months, without improvement. He stopped using the prednisolone enemas but continued to take mesalazine. Within 48 hours of stopping prednisolone his symptoms resolved completely. The theoretical possibility of contact allergy was entertained. Patch tests with a standard battery of contact allergens, including tixocortol pivalate and budesonide, were ++ positive with budesonide. At follow up 3 months later he was symptom free. 

Tixocortol pivalate is a marker for glucocorticoid contact allergy, as a positive patch test suggests established contact allergy to hydrocortisone, prednisolone, and their derivatives (95). A literature search via Medline from 1966 to May 2000 revealed only one patient hypersensitive to tixocortol pivalate and budesonide in a pilot study in 34 patients (10 with asthma, 13 with rhinitis, 11 with both) (96). From case reports, the prevalence of glucocorticoid-induced contact allergy has been estimated at 2.9-5%. 

Contact allergy to glucocorticoids is not rare in patients with atopic dermatitis. In patients with known contact allergy to budesonide, allergic skin reactions can also occur when inhaled forms of the drug are used, as shown by a randomized, double-bhnd, placebo-controlled study in 15 non-asthmatic patients with budesonide hypersensitivity on patch testing (101). In four of seven patients who used inhaled budesonide, there was reactivation of the 6-week-old patch test sites and they had new distant skin lesions. No flare-up reactions were observed in the other 11 patients (three had used inhaled budesonide and eight placebo for 1 week). None of the patients developed respiratory symptoms spirometry and peak expiratory flow rates remained normal. 

There have been only a few reports of contact allergy to povidone-iodine, despite its widespread use. In two cases there were positive patch test reactions on days 2, 3, and 7 to povidone-iodine (5% aqueous) and iodine (0.5% in petrolatum), but negative reactions to povidone itself (34). 

Patch test and photopatch test — to rule out contact and photocontact allergy Immediate-type testing — to rule out contact urticaria... 

Taking the history of the patient and noting the clinical symptoms and localization of the lesions are critical. Allergen identification for a patient with a possible contact allergy to cosmetics is performed by means of patch testing with the standard series, specific cosmetic-test series, the product itself, and all of its ingredients. We can only find the allergens we look for. For skin tests with cosmetic products... 

In a 44-year-old woman who used topical aciclovir for genital herpes, aciclovir contact allergy was associated with a systemic contact allergic reaction with an erythematous vesiculobullous eruption in the labial and perioral skin and a rash on the upper trunk and extremities (25). Patch tests were positive to aciclovir, valaciclovir, and ganciclovir, but not to famciclovir. 

Pre-existing vesicular edematous cheilitis (probably due to contact allergy to the protecting lip salve) was aggravated after application of Zovirax cream (26). Patch tests to the lip salve were positive, but in addition there were positive photopatch tests to Zovirax cream, but not to its separate constituents. 

Contact allergy to topically applied aluminium compounds is rare but skin sensitization has been described (54). In one case the use of a cream for acne and hyperpigmentation was followed by dermatitis, and patch tests were positive to both aluminium sulfate and aluminium chloride. A more typical antecedent of sensitization is the injection of aluminium-adsorbed vaccines, and such patients may present with a granulomatous nodule at the site. Mixed contact sensitivity to nickel and aluminium has been reported to respond to antihistamine therapy (55). 

Fowler JF, Fowler LM, Hunter JE. Allergy to cocamidopropyl betaine may be due to amidoamine a patch test and product use test study. Contact Dermatitis 1997 37(6) 276-81. 

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