Seborrheic Dermatitis

Filed under: 2.1 - Seborrheic Dermatitis

Seborrheic dermatitis is more common in babies under 4 months of age than it is in older children. It is most frequently seen in fat babies, and in looking over the records from my office files of twenty-six babies in whom I had made this diagnosis, on sixteen of the records I had put down a special note that the baby was thriv­ing and very fat. In another consecu­tive series of 100 eczematous babies under 2 years of age, the diagnosis of seborrheic dermatitis had been made in eighteen.

Seborrheic dermatitis often begins with cradle cap, a superficial scaly eruption on the cheeks and intertrigo of the axillae, groins, and neck, and sometimes around the umbilicus. In many patients the trouble goes no further than this. In some, lesions develop on the trunk-the arms and legs are not likely to be involved. Seborrheic dermatitis is essentially a disease of scaling on an inflammatory base; vesiculation is not present, nor is oozing, unless there has been a good deal of rubbing. The lesions on the trunk begin as small, light pink spots, which are covered with yellowish scales. The scales may or may not be greasy. These spots enlarge and coalesce to form still larger areas, which may sometimes be sheetlike in character. There is often clearing in the center, and the margins are sharp. In some cases there may be a more severe degree of inflammatory reac­tion, and the entire skin surface may be covered with large plaquelike scales; seborrheic dermatitis has taken on the characteristics of Leiner’s disease (see below).

In older children intertrigo and cradle cap are not so prominent as in babies, and Leiner’s disease does not occur. As a rule, seborrheic dermati­tis itches but little, there is no eosinophilia, skin tests are negative, and un­less complicated by atopic dermatitis it is not associated with asthma or hay fever. It does, however, in infancy bear some poorly understood relation­ship to atopic dermatitis, and often precedes it. Some babies who have seborrheic dermatitis at the third or fourth month are cured of it with proper treatment-there is no recur­rence and they develop no atopic dermatitis, hay fever, or asthma. In others, characteristic atopic dermatitis, with vesiculation, severe itching, and positive skin tests gradually develop, so seborrheic dermatitis, although not primarily an allergic disease, can and does occur in allergic infants.

Fig. 1.–Seborrheic dermatitis. The lesions are “nummular” in shape, but very different in color and appearance from those seen in nummular eczema. Note piling up of scales and clearing in centers of some lesions.

Fig.   2.-Seborrheic   dermatitis. Fig.  3.-Same    patient    as    in after   treatment.

The cause of seborrheic dermatitis is not well understood. Some have thought that it is due to infection with a yeastlike organism (pityrosporon of Malassez), others that it is from over-activity of the sebaceous glands, others that it has nothing to do with the se­baceous glands, but that it is caused by a deposition of too much fat in the skin from eating too much fat, still others that the cause is lack of a spe­cial dietary factor which is contained in liver, casein, and some vegetables, particularly carrots. It seems possible that all these factors may be opera­tive. The sharply margined lesions certainly suggest infection with a yeastlike fungus, and they respond well to ammoniated mercury or sulfur ointment; in adults seborrheic derma­titis often occurs in places where there are abundant sebaceous glands (the sides of the nose and front of the chest), and in infancy it is undoubt­edly most likely to occur in fat babies who are overfed with milk fat, and a diet low in fat and high in casein is efficient therapeutically.

Treatment is efficient: it is com­bined local and dietetic.

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