No abstract

R-(+)-Limonene is an ubiquitous allergen in our environment. It is one of the most widely used fragrance materials not only in fine fragrances but also most often incorporated in domestic and occupational products. Although the non-oxidized R-(+)-limonene itself is not allergenic, it easily forms allergenic products due to autoxidation during handling and storage. 2273 patients at 4 dermatological clinics in Europe were patch tested between 1997 and 1999 in 2 steps. First, the oxidation mixture of R-(+)-limonene and 1 selected allergen fraction of the mixture, the limonene hydroperoxides, were tested in 2 different vehicles in consecutive patients. A diverging frequency of positive patch test reactions was observed in the 4 clinics. 3.8% of the consecutive patients tested reacted to oxidized R-(+)-limonene in 2 clinics, 6.5% in the 3rd, whereas 0.3% in the 4th clinic. In 2 of the centres, different but significant concomitant positive response rates to other allergens were observed; e.g. to fragrance materials and to colophonium. However, in the total test population, 57% of the limonene-allergic subjects did not react to any of the fragrance allergy markers used in the standard series. In the 2nd step, patients showing positive reactions were retested, also including additional separate allergens of the limonene oxidation mixture (carvone and limonene oxide). 60% of the limonene-allergic patients showed positive results at retesting. The limonene hydroperoxide fraction was proved to be the most important allergen of the oxidation mixture, showing positive reactions in around 60% of the limonene-allergic patients at both test sessions. Testing limonene oxide and carvone separately resulted in very few positive reactions. 3% oxidized R-(+)-limonene in non-stabilized petrolatum is most suitable when using only 1 test preparation for diagnosis of contact allergy to oxidized limonene. Our data give clinical support to the European classification of R-(+)-limonene, containing oxidation products, as a skin sensitizer.

PXE-PDE is a rare clinicopathological entity with few cases reported. It affects more often elderly women and is characterized by asymptomatic bilateral and symmetrical yellowish papules localized predominantly on the neck and supraclavicular regions. It is clinically similar to Pseudoxanthoma Elasticum. The authors report a case of a 64-year-old woman presenting asymptomatic, yellowish, non-follicular papules, affecting the occipital and the posterior region of the neck for 1 year. The patient denied pruritic or inflammatory changes, marked solar exposition or trauma on the affected areas. Routine laboratory studies: thoracic x-ray and ophthalmologic examination were normal. The histopathologic examination of a biopsy of one of the cutaneous lesions showed an absence of elastic fibers in the papillary dermis.The diagnosis of Pseudoxanthoma Elasticum—like Papillary Dermal Elastolysis (PXE-PDE) was made. Of great importance is the differential diagnosis with Pseudoxanthoma elasticum (PXE), but we have also to consider other elastolytic disorders: mid-dermal elastolysis (MDE), linear focal elastosis (LFE) and white fibrous papulosis of the neck (WFPN). Until know, there is no effective treatment for this pathology.

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 jewelery (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.

Most rosin (colophony) used today is chemically modified. Will contact allergy to modified rosin be overlooked when testing is performed with only unmodified rosin in the standard series? 2 components from modified rosins, maleopimaric acid (MPA) and glyceryl I-monoabietate (GMA), earlier identified as contact allergens, were added to the patch test standard series. Some commonly-used modified rosin products were also tested. Positive reactions were observed to the modified components MPA and GMA. Of the patients with positive reactions to MPA and GMA, several did not react to unmodified rosin in the standard series. No reaction was observed to the modified rosin products without a concomitant reaction to unmodified rosin. The positive reactions observed to the modified rosins may be due to residual unmodified material in the product, but a possible contribution from allergenic modified rosin components cannot be disregarded. When a patient's history indicates a rosin allergy, but a negative response to unmodified rosin in the standard series is observed, additional testing with GMA and MPA or, second best, with glycerol-esterified rosin and maleic-anhydride-modified rosin is recommended. Some modified rosin products, which could be used for additional testing, are suggested.