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A 50-year-old woman presented to the clinic with an abrupt onset of an intensely pruritic rash that extended over the dorsal aspect of both arms (Figure 199-1). The patient notes no new medicines and no recent exposures to any new chemicals. She acknowledged recent time spent outside in the sun. The plaques were photodistributed, with sparing of her watch area. A clinical diagnosis of polymorphous light eruption (PMLE) was made, and the patient was started on oral antihistamines and topical steroids. It was recommended that she minimize her sun exposure.

Figure 199-1

Polymorphous light eruption noted over dorsum of left forearm. Note absence of the lesion where the patient had been wearing her watch. (From Wenner C, Lee A. A bright red pruritic rash on the forearms. J Fam Pract. 2007;56(8):627-629. Reproduced with permission from Frontline Medical Communications.)

Photosensitivity is an abnormal skin response to ultraviolet light that occurs on sun-exposed areas of the skin. There are three common types of photodermatitis:

Figure 199-2

Polymorphous light eruption on the arm of a young man. Note the sparing of the skin under his watchband. (Courtesy of Richard P. Usatine, MD.)

Figure 199-3

Severe phototoxic drug reaction secondary to hydrochlorothiazide use. (Courtesy of Richard P. Usatine, MD.)

Figure 199-4

Phototoxic drug reaction secondary to ibuprofen. (Courtesy of Richard P. Usatine, MD.)

Figure 199-5

Phototoxic drug reaction secondary to treatment of vitiligo with oral psoralen and ultraviolet light (phytophotodermatitis). Note the bullae. (Courtesy of Richard P. Usatine, MD.)

Figure 199-6

Phytophotodermatitis in a woman, caused by lime juice and sun exposure on the beach. Note the hand print of her fiancé who had been squeezing limes into their tropical drinks. This contact occurred when they posed for a photograph. (From Darby-Stewart AL, Edwards FD, Perry KJ. Hyperpigmentation and vesicles after beach vacation. Phytophotodermatitis. J Fam Pract. 2006;55(12):1050-1053. Reproduced with permission from Frontline Medical Communications.)

Figure 199-7

Phytophotodermatitis visible on the arm, trunk, and leg caused by lime juice and sun exposure on the beach. Note the hyperpigmentation that occurs in conjunction with the erythema. (From Darby-Stewart AL, Edwards ...

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