Contact Dermatitis
Filed under: 3.5 - Contact DermatitisI am writing especially for pediatricians. I will therefore start this section by suggesting to them that it would be best if they discarded the idea that all eczematous skin eruptions in infants and children are caused by what they eat and cured by removing some food from the diet.
Contact dermatitis is the most common eczema of adults. It is not so common in infants and children because they are not exposed to the multiplicity of skin sensitizers that adults are. In 156 consecutive cases of eczema from my office records, in patients between the ages of 1 and 17 years, I made the diagnosis of contact eczema thirty-one times. I have no figures for young babies. I doubt if the percentage would be so high; however, it is common enough so that the possibility of it should always be borne in mind.
Contact dermatitis may be caused by irritation of the skin by substances which cause irritation in all persons (primary irritants) or by substances which irritate only when the patient has become allergically sensitized to them. The epidermis is the seat of sensitization-there are, so far as is known, no circulating antibodies, no hereditary predisposition as there is in atopic dermatitis, and no association, except fortuitously, with asthma or hay fever. Contact dermatitis is an episode, atopic dermatitis a disease ; the episode is not uncommonly superimposed upon the disease and a contact dermatitis may be added to
an existing atopic dermatitis. I think it is probable that those who have atopic dermatitis are somewhat more likely to develop contact dermatitis than are those who do not have it. Not all would agree with this.
The causes are innumerable: metals, dyes, essential oils, plastics, cosmetics, turpentine, plant oils, drugs-indeed, chemicals of almost any sort, organic or inorganic, which come into contact with the skin.
The most important things in the treatment of contact dermatitis are:
(1) To be on the lookout for it, and to realize that it occurs at any age. To decide whether or not you are dealing with a contact dermatitis.
(2) To get at the cause, if possible, and remove it.
(3) To keep the skin entirely protected from contact with anything which might do it harm.
(4) Local treatment with various lotions, pastes, or ointments: the same as for atopic dermatitis. (See atopic dermatitis.)
The appearance of the skin in acute contact dermatitis varies all the way from simple erythema, with slight scaling, to the most intense vesicula-tion, or even bullae. If such eczema appears rather suddenly on a previously healthy skin, particularly if it appears in one place on an exposed surface, contact dermatitis should always be considered. In chronic cases there is a good deal of thickening and even lichenification, so that the appearance may closely resemble that of atopic dermatitis. The borders are not sharp, and the trouble may, in a short time, spread from the point of original contact, sometimes by transfer with the fingers, probably sometimes through the blood stream.
Fig. 20.-Contact dermatitis from Metaphen nose drops. Patch test to mercury strongly positive. (From Lirennemann’s Practice of Pediatrics.)
Fig. 21.-Contact dermatitis from ammoniated mercury ointment. Local treatment: zinc oxide paste (U.S.P.). (From Brennemann’s Practice of Pediatrics.)
It is usually not hard to be reasonably sure from the history and from the appearance and location of the eruption that a contact eczema is present, but determination of the cause is quite another matter. All too commonly it is never determined. I have done a great many patch tests in children when I knew that the eczema was of external origin, and have seen few positive tests. I think the probable reason is that in many of these children the degree of sensitization is not great enough to cause dermatitis unless the contact is prolonged and there is a certain amount of trauma of the skin as well (rubbing). The extreme degree of sensitivity that is so often seen in adults is not so commonly seen in children, although I see no reason why, if they were sensitized to some of the things that cause so much trouble in adults (such as paraphenylenediamine or various metallic salts), they should not give as well-marked patch tests as the adults do. The children shown in Figs. 20 and 21, who were sensitive to mercury, gave well-marked positive patch tests.
Some of the things to suspect are as follows: “baby oils,” most of which contain essential oils (aromatic amines), salves or lotions which have been used in treatment, toilet water or other cosmetics, shampoos, turpentine, detergents or bleaching powders, dyes or “finishers” in clothes (very important), plastics, lacquered toilet seats, plants, and toys. I have never seen contact dermatitis from soap,* although it undoubtedly does occur. I have seen proved contact dermatitis in children from the following things: dyes, mother’s cosmetics, primrose, ivy, the leaves of the white mulberry bush, plastics, toilet seat lacquer, ammoniated mercury, tar, sulfur, Sopronol, a proprietary shampoo, furniture polish, hair tonic, turpentine, creosote, and tincture of green soap.
*Except from tincture of green soap, due to the lavender it contains.
Note: I have used the words “eczema” and “dermatitis” interchangeably.
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