When it comes to solving mysteries, a super sleuth like Sherlock Holmes has nothing on a good dermatologist.
Consider the case of the woman whose 21-year-long bout of eczema of the right palm was traced by her dermatologist to a carving knife she received as a wedding present 21 years before. The knife's wooden handle was the culprit causing her allergic rash.
Or the lady who had eczema of the palms for six years. The dermatologist deduced that the guilty party was the car she had bought six years earlier--the steering wheel contained a compound to which she was allergic.
Or the recent widower who suddenly developed an itchy rash on his hands. His dermatologist determined that it was not a psychosomatic disorder brought on by grief, but a sensitivity to oils in the skin of oranges, which he was squeezing for himself for the first time.
Allergies
The red, raw hands that tormented these people resulted from the skin's reaction to a substance (allergen) to which they had become sensitized, or allergic. This type of eczema, or superficial skin inflammation, is called allergic contact dermatitis. Normally, the skin doesn't react the first time it meets up with an allergen. Sometimes it occurs with the second exposure. But in other cases, it takes years and many exposures for hypersensitivity to a particular substance to develop. Once sensitized, the skin will usually become inflamed within hours or days after contact.
Irritants
Unlike allergic contact dermatitis, irritant contact dermatitis--a more common type--is a nonallergic inflammatory skin reaction caused by exposure to irritating substances that actually damage the skin. Not everyone develops allergies, but everybody's skin can become irritated if abused. Contact with strong irritants, such as acid or lye, can result in blisters, erosion and ulcers within minutes or hours. For weaker irritants, such as soaps or detergents, exposure over days or weeks may be necessary before eczema develops. Any substance can act as an irritant if it is concentrated enough and if the skin is exposed to it long enough.
The eczema usually starts with a red, itchy rash and progresses to tiny blisters that ooze.
Doctors can usually distinguish contact dermatitis from other types of dermatitis by its unusual pattern. The eruption often appears with clear-cut margins, acute angles, and geometric outlines, although poison ivy and other poison plants cause lines or groups of blisters.
Though the configuration of the rash aids in diagnosis, it's not so easy to determine whether an allergy or irritant is involved. The skin reaction produced by either, especially when mild, frequently looks the same. Redness or an itchy rash may be the first sign. However, blisters that weep or form a crust, along with swelling, are more likely to appear in allergic dermatitis, such as poison ivy. As the inflammation lessens, the skin may scale and become temporarily thickened. When the dermatitis becomes chronic, the skin becomes dry, thickened and cracking.
Sometimes, if the inflammation with mild irritants continues for a long time, the original irritation disappears because the skin becomes hardened.
Finding the Source
A person may know what caused the inflammation--for example, recent hand contact with a corrosive, such as an oven cleaner--or may not have a clue. The patient's hobbies, diet, occupation, sports activities, clothing and cosmetics, as well as medications that are taken internally--all come under suspicion.
An irritant or allergen at home or at work may be responsible. In one particularly puzzling case, Walter B. Shelley, M.D., Professor of Dermatology, Medical College of Ohio in Toledo, decided to visit the home of a patient who had been hospitalized twice for severe contact dermatitis. All tests had been negative, but after seeing her stainless steel kitchen, the cause of the dermatitis was apparent--the stainless steel polish she used to keep her kitchen shiny.
The location of the rash will sometimes tell the tale--except for hands, which are into everything. Anything on the scalp, face and neck suggests cosmetics such as hair sprays, shampoos, makeup, sunscreens, perfumes, shaving cream, acne medications--the list is endless. Eyelid dermatitis is often traced to nail polish, which can cause an allergic reaction if nails touch the eye area before the polish dries completely, a two-hour process. Lips can become sensitive to ingredients in lipsticks, toothpastes or chapped lip medications. Armpits can become allergic to or irritated by ingredients in deodorants or antiperspirants.
Dyes, elastic materials, fabric finishes such as sizing and permanent press, laundry detergents, and fabric softeners can cause dermatitis on the torso and arms and legs. "Some of those antistatic laundry products are really mean," says Shelley. "They can cause terrible problems. They set off itching, and people scratch, of course, which only makes things worse. It takes a lot of laundering to get that stuff out of the clothes." The feet can be affected by dyes, rubber compounds, and leather-tanning products in shoes, or elastic fibers in hosiery. Nickel--used in jewelry, bra fasteners, eyelash curlers, metallic eyeglass frames, and many other products--can produce inflammation wherever it touches the body. People may become sensitized to nickel from ear-piercing instruments and from nickel-plated earrings inserted after piercing.
Fragrances in cosmetics are frequent offenders. Redness under the ears may be caused by perfume dermatitis. Some components of fragrances may interact with sunlight or other sources of ultraviolet light to produce dermatitis by a process called photosensitization. When dermatitis occurs on the left side of a man's face and neck--the side exposed to the sun while driving a car--photosensitization caused by aftershave lotion fragrances should be suspected.
Betrayed by Medications
And the unkindest cut of all--people can become sensitized to the very medications that they're using to relieve a skin problem, such as acne. If a skin product does not seem to be working, if things are getting worse instead of better, there's a chance that an allergy to some ingredient in the medication has developed, especially if puffiness, redness and itching appear.
Dermatitis may be caused by topical (externally applied) medications, such as anesthetics containing benzocaine, dibucaine and other chemicals that end in "caine," topical antibiotics such as neomycin and streptomycin, topical antihistamines such as diphenhydramine and promethazine, and topical mercury compounds such as mercurochrome and merthiolate.
Some drugs delivered to the individual by skin patches (transdermal therapeutic systems)--such as scopolamine for motion sickness, and clonidine and nitroglycerin for treatment of cardiovascular disease--can cause either irritant or allergic dermatitis, due either to the drug itself, a patch component, or the adhesive.
In addition, people who've been contact-sensitized by certain topical drugs may develop fever, feel unwell, or have excessive thirst when they take the drug orally as a tablet or capsule, or by injection.
Even inhaling the vapor can cause problems. One example of inhalation-related dermatitis is the "baboon syndrome" (named after the red-bottomed baboon), a curious type of red, spreading rash that develops on the buttocks and upper thighs. Japanese doctors have reported a number of cases in which mercury-allergic people, previously sensitized by the use of mercurochrome on the skin, developed the syndrome after inhaling the vapor from crushed thermometers. This ailment points out the importance of never allowing mercury to touch the skin. Alexander Fisher, M.D., one of the world's leading dermatologists, advises in Current Dermatologic Therapy (ed. Stuart Maddin, M.D.) that if a thermometer breaks, a "shiny copper object, such as a penny," should be used to pick up the mercury.
Allergy Testing
If the physician suspects an allergy, patch testing may identify the responsible agent. However, to prevent the condition from worsening, these tests are not done until the inflammation has subsided.
The dermatologist uses a series of medicines, metals, preservatives, rubber compounds, and various chemicals that go by the name North American Contact Dermatitis Group Standard Patch Test Series. A small amount of the suspected allergen(s) is applied to the patient's back, covered with a nonabsorbent adhesive patch, and left on for 48 hours. (The patch is removed if itching or burning develops before that time.) If redness, some hardness, or blistering occurs, the test is considered positive, indicating probable allergy to the substance. Since some reactions do not occur until after the patches are removed, the doctor will take another look at the patch sites in 72 hours.
Other patch test series are available if the tests are negative.
Occupational Contact
Sometimes, the offending allergen can't be easily identified. But dermatologists don't like to give up.
"When the allergen is not found, you just keep looking. So many of these cases are due to occupational contact," says Shelley. "While you're looking, treatment is directed at relieving the inflammation. It's rare that you can't do something for the patient."
Industrial statistics show that contact dermatitis accounts for more than 50 percent of all occupational illness, excluding injury, and results in about a fourth of the time lost from work. About one in every thousand workers in the United States suffers from contact dermatitis, costing millions of dollars each year.
Occupational dermatitis is common among hairdressers, workers who handle animal intestines in slaughterhouses, shrimp peelers, furniture makers working with woods like teak and African mahogany, bakers in contact with cinnamon, and many others. People with hay fever and asthma or other allergies are well advised to stay away from occupations in which they would be exposed to chemicals, water and soil, because their skin is more susceptible to dermatitis. In the workplace, about 70 percent of contact dermatitis cases are irritant and 30 percent are allergic.
A Lifelong Problem
Contact dermatitis can make its appearance as early as infancy. Acute skin problems account for one-third of visits to the pediatrician, with irritant dermatitis the most frequent type in children. A baby's thin delicate skin can become irritated from urine and bowel movements, or it can become allergic to a chemical in the diaper or medicines used to treat diaper rash.
Dermatitis of the cheeks and around the mouth can occur as a result of irritation by drooling, water, juices, food, and dry air. A rash all over the body and in the folds of a baby's skin may result from contact with detergents, soaps, fabric softeners, and bleach.
Problems can continue throughout adulthood. The problem of "dishpan" hands is common in those whose hands are constantly in contact with water, soaps or detergents. Sun lovers may develop an itchy rash following too much of a good thing, especially after the first exposure in the spring or summer. Ski enthusiasts are familiar with dermatitis and chapped skin from exposure to cold, dry air.
Frictional irritant dermatitis can result from improperly fitted shoes. Handling golf clubs and tennis rackets may produce inflamed skin, blisters and calluses. Tattooing has its dangers--people who've been sensitized to mercury, chromium, cobalt, and cadmium can develop rashes and roughened skin when tattooed with the salts of these metals.
Neither do the elderly escape. Topical medications should be used with care by older people, because changes in the skin make it more susceptible to dermatitis, and it generally takes longer to clear up than in younger patients.
Treatment
For self-treatment of mild contact dermatitis, a .5 percent hydrocortisone topical preparation (ointment, cream or lotion) can be applied to the skin to relieve the itchiness, redness, scaling, and swelling. Because these formerly prescription-only medications had a good safety record, FDA approved them for over-the-counter sale in 1979 on the recommendation of the Advisory Review Panel on OTC Topical Analgesic, Antirheumatic, Otic, Burn and Sunburn Prevention Treatment Drug Products. A petition to make 1 percent topical hydrocortisone drug products available for over-the-counter sale is currently being evaluated by the agency.
The labeling of the OTC products states that if symptoms worsen or persist longer than seven days, a doctor should be consulted. (Occasionally, bacterial or fungal infections superimpose themselves on the dermatitis.) The labeling also cautions against internal use and use on children under 2 years. Lubricating creams or lotions, preferably preservative- and lanolin-free, can be used to prevent cracking and dryness, especially of the hands, and the irritating factor or allergen should be avoided whenever possible.
Severe cases should be seen by a doctor. Stronger concentrations of topical corticosteroid preparations or oral corticosteroids, such as prednisone, may be prescribed. If there's a secondary infection, an oral antibiotic may be necessary.
When inflammation has gone on for a long time, an extended period of convalescence is often necessary. "I tell my patients it's like skin that's been burned after sitting on a hot stove," comments dermatologist Shelley. "You've got to allow time for the skin to heal itself."
Evelyn Zamula is a free-lance writer in Potomac, Md.
Preventing Skin Inflammation
Sensitive-skinned people--and even those with tougher hides--would do well to follow a number of measures to prevent contact dermatitis:
--E.Z.
Common Sensitizers
Among common sensitizers, poison ivy leads the pack. Estimates of Americans with poison ivy allergy range from 50 to 70 percent. Most of the rest of the population would develop poison ivy dermatitis on further exposures, though some people will never get it. Cross-sensitization to other members of the poison ivy family occurs, so that allergy can develop to poison oak, poison sumac, the oil in cashew nutshells, mango fruit peel and leaves, and the fruit of gingko trees. A severe airborne dermatitis can result from contact with the smoke from burning plants on exposed skin.
In mild cases, topical corticosteroids are used to relieve the itching, while severe cases are treated with oral or injected corticosteroids. In severe cases, hospitalization is sometimes necessary. Unfortunately, shots or medicines for desensitization to poison ivy have not been very effective and, in fact, can make poison ivy dermatitis worse.
Some common house and garden plants are not completely innocuous, either. Primroses and philodendrons cause allergic dermatitis in some people. Handling tulip bulbs may result in a sensitivity known as "tulip fingers." Asters, chrysanthemums, English ivy, castor beans, oleanders, geraniums, poinsettias, magnolias, lilacs, narcissus, and other bulb plants can be sensitizers, as can ragweed, some pollens, such as birch pollen (which can cross-sensitize to apples, carrots and celery), and the timber and sawdust of some trees.
Some vegetables may also cause a problem. Dermatitis can result from handling parsnips, garlic, onions, tomatoes, carrots, and ginger.
Nickel, the most common metallic sensitizer, produces more allergic dermatitis than all other metals combined. Other common sensitizers are permanent hair dyes containing the chemical paraphenylenediamine, rubber compounds, and the chemical ethylenediamine, found in dyes, insecticides, synthetic waxes, and used as a preservative in some medicines.
--E.Z.