MONTEREY, CALIF. – “Consort dermatitis” – when a patient is allergic to his or her partner. “Lime dermatitis” – when gin and tonics are the culprit. And “sample dermatitis” – when an unprescribed drug sample turns out to be the cause of a mysterious reaction.
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Dermatologist Vincent DeLeo, MD, of the University of Southern California, Los Angeles, has seen them all. He provided insight about how to diagnose these unusual conditions at the Coastal Dermatology Symposium.
The following are a few unusual causes of dermatitis that he discussed:
- Romantic partners. A patient’s partner can be the cause of a reaction, as in the case of a 25-year-old woman who turned out to be allergic to her boyfriend’s cologne. In another case, a 50-year-old man had a 3-year history of recurrent dermatitis on his left arm and the left side of his chest. The cause was a mystery until it became clear that it was caused by exposure to hair dye, but not his. “He didn’t color his hair, but his wife did, and she always slept on that side of him,” Dr. DeLeo recalled. “When she stopped coloring her hair, his disease cleared.”
- Black henna. The dye known as “black henna,” or just “henna,” can cause reactions in adults (who use it as a hair dye or to decorate the skin) and children (who can be exposed to it with temporary tattoos). “Because henna typically produces a brown, orange-brown, or reddish-brown tint, other ingredients must be added to produce other colors, such as those marketed as ‘black henna’ and ‘blue henna,’ ” according to a Food and Drug Administration statement. “Even brown shades of products marketed as henna may contain other ingredients intended to make them darker or make the stain last longer on the skin. The problem? “The extra ingredient used to blacken henna is often a coal-tar hair dye containing p-Phenylenediamine, an ingredient that can cause dangerous skin reactions in some people,” the statement says. Dr. DeLeo said that one good rule of thumb is to consider a reaction to black henna if a patient acknowledges using a henna dye and their hair is any color but red. That’s a sign, he said, that they’re actually using black henna.
- Makeup applicators. Dr. DeLeo has seen two cases of patients with facial dermatitis who turned out to be allergic to thiuram, a component of rubber. Their skin was reacting to the rubber in some sponges used to apply makeup.
- Lime and sun exposure. Patients are impressed when Dr. DeLeo correctly guesses what they were drinking the previous weekend, because of their telltale blisters indicating a lime allergy. Noninflammatory blisters on the fingers or hyperpigmentation can be caused by touching the skin of a lime and then having subsequent exposure to ultraviolet light. It may take days for the blisters to appear, he noted. A weekend after mixing gin and tonics with lime, for example, a patient “may show up on Tuesday of the following week. The patient doesn’t always think of what they did over the weekend.”
- Liquid detergents. As a general rule, laundry detergents do not cause dermatitis, Dr. DeLeo said. “By the time that clothing is rinsed in your washer, there’s not enough left of anything on the clothing to cause a problem.” But there’s an exception: When people hand wash clothing with liquid detergents, such as Woolite. “It’s not the fragrance,” he said. “It’s the preservative in the detergent.”
- Unexpected nickel. Skin allergy to nickel is common, and the metal can lurk in unexpected places, as he discovered when he treated a Columbia University student who was “allergic to his tuba.” The tuba was made of brass, not nickel. But “the little things connecting the tubes to each other are alloy metals,” he said, including nickel.
- Drug samples. Dr. DeLeo recalled the case of a dermatology office administrator with a recurrent neck rash. Dermatologist after dermatologist failed to find the cause. Patch and photopatch testing turned up nothing. Then Dr. DeLeo asked her to bring in every skin product she was using. She returned with a large bag full of dermatologic samples, including Drithocreme (anthralin), which can be an irritant. None of the drugs were prescribed. “This is case of sample dermatitis,” which may occur among employees and family members of dermatologists, he said. “Always think of having patients bring in what they’re using,” he added, “because you can be surprised.”
The Coastal Dermatology Symposium is jointly presented by the University of Louisville and Global Academy for Medical Education. This publication and Global Academy for Medical Education are both owned by Frontline Medical Communications.
Dr. DeLeo disclosed consulting work for Estée Lauder.