Seborrhoeic dermatitis

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Seborrhoeic dermatitis

Seborrhoeic dermatitis is a common chronic disease characterised by inflammation and desquamation in skin regions with high sebum production and the large body folds. Seborrhoea, abnormal sebum composition and the commensal yeast Malassezia furfur play a role in the pathogenesis of this disorder. An infantile and an adult form of this disorder are distinguished. The adult form displays a peak in the fourth to sixth decades and is more common in men than in women

Clinical picture:

Infantile seborrhoeic dermatitis presents initially with mild, greasy scales on the scalp, often 1 week after birth. Inflammation and oozing may follow, resulting in a crusty mass covering most of the scalp, and red and scaly lesions may also cover other body parts.
In adults, pityriasis simplex capillitii, a white greasy scaling of the capillitium without signs of inflammation, is the mildest form of seborrhoeic dermatitis of the scalp. When inflammation is present, the patients display red scaly lesions on the scalp or other body parts. Adult seborrhoeic dermatitis shows a relapsing course.
The skin is usually sensitive to irritation, and exposure to sun, heat or irritative topical agents may precipitate flares. Usually there is moderate, sometimes even intense itching.

Distribution:

Up to 95% of affected patients have scalp lesions. Other predilection sites include the eyebrows, forehead, nasolabial folds, cheeks, retroauricular areas, presternal and interscapular regions as well as the intertriginous areas.

Diagnosis:

The diagnosis is based on the clinical picture and on the exclusion of other diseases.

Differential diagnoses:

In infants, atopic dermatitis should be distinguished, as well as Langerhans cell histiocytosis and Wiskott-Aldrich syndrome. Psoriasis is another possible differential diagnosis. Seborrhoeic dermatitis of the face has to be distinguished from rosacea and systemic lupus erythematosus. Lesions in the intertriginous areas may resemble erythrasma, inverse psoriasis, candidiasis and intertriginous dermatitis.
A chronic therapy-resistent course of seborrhoeic dermatitis may point to an underlying HIV-infection.