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Berloque dermatitis obtains its name from the German word berlock or the French berloque, meaning trinket or charm. Rosenthal coined the term in 1925 to describe pendantlike streaks of pigmentation on the neck, face, arms, or trunk. He suspected they were due to fluid droplets, unaware that Freund in 1916 had described hyperpigmented macules due to sun exposure after the application of eau de cologne. The phototoxic ingredient causing the pigmentation proved to be bergapten, a component of oil of bergamot, derived from the rind of Citrus bergamia, the bergamot lime. Several cases were reported in the 1950s and 1960s following increased use of perfumes containing oil of bergamot and the passion for sunbathing. Since the introduction of artificial oil of bergamot and the reduced use of the natural product in perfumes, berloque dermatitis has become rare. Note the image below.
The clinical presentation of berloque dermatitis may be classically divided into 2 phases. The initial acute inflammatory phase consists of erythema, edema, pain, pruritus, and increase in skin temperature around the area of contact with the phototoxic agent. The second stage is hyperpigmentation of the lesion. Patients usually present with small areas of redness or pigmentation of the skin, usually on sun-exposed areas, such as the neck. Pain and, sometimes, pruritus may be felt during the acute erythematous phase before the lesions become hyperpigmented. However, hyperpigmentation is the chief complaint; sometimes patients may not even recall the inflammatory phase. A careful history may reveal use of a perfume or fragrance-containing product on the skin prior to a period of sun exposure, such as sunbathing or a picnic. If untreated, the natural history of the disease also is biphasic; the inflammatory lesions resolve in days to weeks, but the pigmentation may last months or even years.
Phototoxicity testing is not carried out diagnostically, but rather for predictive purposes. It routinely is included in the safety evaluation of raw materials by the Research Institute for Fragrance Materials and several methods for identifying phototoxic compounds have been reported. Both in vitro and in vivo methods are used currently. Generally, for in vivo testing, measured amounts of fragrance material are tested, either in laboratory animals (eg, mouse, rabbit, guinea pig models), or ultimately in humans, with an artificial light source. This identifies potential phototoxic substances before they are marketed.
In an attempt to decrease animal use in predictive dermatology, the European Union, in cooperation with the European Centre for the Validation of Alternative Methods (ECVAM) and the Interagency Coordinating Committee for the Validation of Alternative Methods (ICVAM), has supported the development of in vitro alternatives.[8, 9, 10, 11] Initial trials revealed reasonable sensitivity and specificity[12, 13, 14, 15] ; false-positive results and false-negative results have already been documented.[16, 17, 18] Thus far, several cosmetic products have been examined in vitro for phototoxicity.
The primary aim of the therapeutic regime is discontinuation of the offending substance. If berloque dermatitis is the putative diagnosis, all bergamot oil-containing perfumes should be avoided. Any perfumes that are worn should be worn on covered-up areas, not on areas of sun exposure.
If the patient presents in the acute phase and is in considerable discomfort, wet compresses may be helpful in relieving the discomfort; a short course of topical corticosteroids may also be helpful. Simple analgesia may be given if the patient is in pain.
For secondary hyperpigmentation, the natural course of the dermatitis is spontaneous resolution after several months, but some lesions may persist much longer. The most important step is to minimize exposure to the sun. This may be done by avoiding strong sunlight whenever possible, avoiding the use of sunbeds and using a strong sunscreen (SPF 30 or higher) with activity in both the UVA and UVB spectra. Camouflage also may be used on exposed hyperpigmented areas, for cosmetic reasons. Dermablend and Covermark are preparations combining a water-resistant opaque base with a broad-spectrum sunscreen.
If the pigmentation is persistent, hydroquinone constitutes the mainstay of medical therapy. It usually is given twice a day, at a concentration of about 2%, for several months. At higher concentrations, the patient would be at risk of irritation. Hydroquinone sometimes is administered in conjunction with topical tretinoin (Retin-A). Kligman and Willis devised a concoction known as Kligman's formula, consisting of hydroquinone, tretinoin, dexamethasone, ethanol, and propylene glycol, which they found effective in treating hyperpigmentation.
Proceed to Medication
Medical therapy is largely unnecessary for the treatment of berloque dermatitis, except in cases with persistent hyperpigmentation. In these cases, skin-bleaching agents (eg, hydroquinone) are the mainstays of therapy.