Elvira Silva

Allergic contact dermatitis to Aloe vera

We present the case of a 72‐year‐old woman observed for dermatitis on the legs followed by apperance of erythema on the eyelids. She had a past history of peripheral venous insufficiency and had been using self home‐made Aloe vera juice over the legs for relief from pain. Patch tests showed positive reactions to the leaf of Aloe, the macerated Aloe jelly, and nickel sulfate. Although most manufacturers process Aloe products avoiding its irritant extracts, and probably as a consequence reports of allergic reactions are rare, one must remember that the growing popularity on the use of Aloe products may stimulate its use ‘as is’ by the patients. Furthermore, it is important to specifically ask patients about the use of these products, because they consider it as innocuous and thus would not spontaneously provide such information.

Contact allergy to gold sodium thiosulfate: A comparative study

During 1995, we added gold sodium thiosulfate and potassium dicyanoaurate to the patch test standard series. Our purpose was to compare the reactivity of the gold salts, to determine the frequency of contact allergy to gold in our country, to compare our results with those of the Malmö group and, finally, to try to clarify the clinical relevance. 2853 patients were routinely tested and 168 patients answered a questionnaire similar to that used by the Malmö group. Contact allergy to gold was found in 23 patients; all women: 22 to gold sodium thiosulfate (0.78%). only 1 to potassium dicyanoaurate and 2 to both salts. All reactors had their ears pierced and were exposed to gold jewellery (mainly earrings). Simultaneous allergies to nickel and cobalt were statistically significant in patients with positive patch tests to gold sodium thiosulfate. Atopy was no more common among these patients.

Immediate and Delayed Hypersensitivity to Mite Antigens in Atopic Dermatitis

Atopic dermatitis (AD) is a common disorder and appears to be on the increase, especially among children. It was thought at first to be a manifestation of immediate hypersensitivity, but it is now known that delayed hypersensitivity also plays an important role. Sensitivity to mite antigens is found in 20% to 60% of patients when immediate hypersensitivity is evaluated by the detection of specific IgE antibodies and prick tests, and in 30% to 50% of patients when delayed hypersensitivity is studied by patch testing. A prospective randomized study was carried out in the pediatric dermatology clinic on a sample of 51 children under 15 years of age. A prevalence of immediate and delayed hypersensitivity to mites, like that described for other populations, was found. It was further found that there was a positive association, not described in the literature, between the younger age groups and delayed hypersensitivity to mite antigens, while the opposite was true for immediate hypersensitivity. We believe that patch tests with airborne allergens, specifically mites, should be part of the protocol for assessing children with AD, particularly in the younger age groups.

Severe contact allergy to footwear in a young child

A 5-year-old female patient, with plantar juvenil dermatitis and family and personal history of atopic dermatitis, presented with bilateral and symmetrical diffuse erythema, vesicles, bullae and exulcerations on the dorsum of her feet and toes as well as on the plantar surfaces, with severe itching (Figs 1 and 2). The lesions evolved for 1 year and aggravated whenever she wore shoes, especially in summer. The severity of the clinical picture kept her away from school causing a significant impact in her psychosocial development. Patch tests with standard series of Portuguese Contact Dermatitis Group (GPEDC) and shoe series (Chemotechnique) resulted in the reactions summarized in Table 1. We advised the parents to use chromium-free tanned leather footwear over 2 pair of cotton socks. We also stressed the need of having 2 pairs of shoes to alternate day-byday, allowing them to dry. Although not sensitized, the use of rubber shoes was not recommended. Occlusion and moist environment would worsen juvenile plantar dermatitis and could promote new sensitizations. The use of topics containing Balsam of Peru was forbidden. With these strategies and topical corticosteroids, the lesions improved gradually and disappeared in 3 weeks with no recurrence in a 6-month follow-up.

Piroxicam-β-cyclodextrin and photosensitivity reactions

Piroxicam is one of the more frequently prescribed nonsteroidal anti-inflammatory drugs (NSAIDs) in Portugal, due to its efficacy and once-daily dosage (1). A new piroxicam formulation has recently been marketed in Portugal: piroxicam-b-cyclodextrine (PBCD; BrexinA), the result of supermolecular encapsulation of piroxicam with the cyclic oligosaccharide b-ciclodextrine, which results in increased bioavailibility (2). Piroxicam photosensitivity reactions are well-known (3). Their proximate cause is a photoproduct, induced by the UVA radiation, which cross-reacts with thimerosal (4, 5). In 1996, thimerosal accounted for 15.4% of patch test reactions in the grouped data of the GPEDC (6).