SEBORRHEIC DERMATITIS (SEBORRHEIC ECZEMA, DERMATITIS SEBORRHEICA)

Synonyms.   Seborrheic eczema, dermatitis seborrheica.

Seborrheic dermatitis is an inflammatory disease of the skin that usually begins on the scalp from which it spreads to the face, neck, and body. The disease is characterized by dry, moist, or greasy scales, and by crusted, pinkish-yellow or yellowish patches of various shapes and sizes; by remis­sions and exacerbations, and by more or less itching. The sites of predilec­tion are areas in which sebaceous and sweat glands are present in large numbers. Parts commonly affected are the scalp, supraorbital region, lids, nasolabial crease, lips, ears, sternal area, axillae, submammary folds, um­bilicus, groins and gluteal crease. The disease usually runs a chronic course.

For the sake of clarity the different expressions of seborrheic dermatitis will be considered topographically.

On the scalp the least severe phase—pityriasis sicca—manifests itself as a dry flaky branny desquamation, beginning in small patches and rapidly involving the entire surface, with a profuse amount of fine powdery scales. An oily type of dandruff, pityriasis steatoides, at times accompanied by erythema and an accumulation of thick crusts, is also encountered. There is a tendency for the hair in the affected areas to fall out, characteristically beginning on the vertex and frontal regions and progressively receding. It is commonly associated with premature baldness in men. Other types of seborrheic dermatitis on the scalp are more severe and are manifested by greasy, scaling configurate patches or psoriasiform eruptions, exudation, and thick crusting. The disease frequently spreads beyond the hairy scalp to the forehead, ears, postauricular regions and neck. On these areas, the patches have convex borders and a reddish-yellow or yellowish color that is quite characteristic. In extreme cases the entire scalp is covered by a greasy, dirty crust which has an offensive odor. In infancy, yellow or brown scaling lesions on the scalp and accumulated epithelial debris is called cradle cap.

On the supraorbital regions, dandruff is seen in the eyebrows, and the underlying skin is erythematous and pruritic, or may show definite yel­lowish scaling patches. The edges of the lids may be erythematous and granular (marginal blepharitis). The conjunctivae are injected. The lids may be involved by yellowish-pink, finely scaly patches, the borders of which are usually indistinct. More or less pruritus may be present. If the glabella is involved, there may be cracks in the skin in the wrinkles at the inner end of the eyebrow. In the nasolabial creases and on the alae nasi, there is a yellowish or reddish-yellow scaling, sometimes with fissures. In men, folliculitis of the upper lip may occur. There is characteristic scaling

in the aural canals and when the disease is more advanced, there are scaly pruritic patches around the auditory meatus and in the postauricular region, or under the lobe. In these areas the skin often becomes red, fis­sured and swollen. Serous exudation, puffiness of the ears and surrounding parts, and regional adenopathy occur less frequently. In other cases a papular type of eruption is present on the cheeks, nose and forehead, the papules being scaly, greasy, yellowish or yellow-red in color, and 1 to 3 mm. in diameter.

The lips and mucosae are not usually involved but sometimes the changes on the lips are pronounced, resulting in cheilitis exfoliativa. The vermilion surfaces are persistently dry, red, scaly, exfoliative and fissured.

In the axillae, the eruption begins in the folds of skin at the apex and later progresses to neighboring skin. The involvement may vary from simple yellowish erythema and scaling, to more pronounced petaloid or discoid patches with fissures.

Seborrheic dermatitis is common in the groins and gluteal crease whert its appearance may simulate ringworm. The patches, however, are more finely scaly with less definite borders, and are more likely to be bilateral and symmetrical and of the typical color. In these locations, fissures occur and there may be psoriasiform patches with thick scales in the more severe cases.

On the upper and lower extremities the patches are more eczematoid, often lacking the characteristic color and fineness of scale. Vesicular exu­dative and crusted patches are not uncommon. The palms and soles may show a pompholyx-like vesicular eruption or may be diffusely thickened and scaly. Even the nails may be involved, showing longitudinal and trans­verse ridges, brittleness and grayish discoloration.

The lesions may be widely distributed or generalized, with erythema, scaling, oozing, and more or less pruritus. Often for months or years the eruption remains localized to one area, such as the scalp, ears, sternal region or umbilicus. Less frequently subacute or acute types are seen. In the acute stages the inflammation may be intense with profuse swelling of the eyelids and face, moist exudation from the scalp and ears, and papulovesicles on the palms and soles. Secondary infections causing fur-unculosis frequently ensue. On the extremities the cubital and popliteal regions often become lichenified from scratching and the friction of cloth­ing. Generalized eruptions may be accompanied by adenopathy and may simulate mycosis fungoides and leukemic erythroderma.