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This usually commences from the teens upwards. It tends to be a chronic dermatitis which often is very itchy and is aggravated by stress and fatigue. Seasonal variations are common. It may be an early presentation of HIV. Yeast of the genus malassezia, (formerly known as, Pityrosporum ovale) is implicated by many as the contributing organism (1).
The prevalence of seborrhoeic dermatitis in immunocompetent adults is around 1-3% (1).
Scalp, periorbital, auricular and nasolabial folds are most often affected. A severe and persistent dandruff is often the presenting complaint. The presternal and interscapular areas, and especially in women, the intertriginous areas can be affected, with severe cases becoming generalised.
There is erythema and scaling which may be fine and white, or thick and yellow. Occasionally, there is crusting with weeping and infrequently, perifollicular pustules.
Seborrhoeic dermatitis is seen in two clinical subtypes on the chest. The petaloid type is the most common form, with reddish brown follicular and perifollicular papules with greasy scales. The papules can expand to form patches in the shape of flower petals or medallions. Pityriasiform type occurs rarely, resembling extensive pityriasis rosea (2).
In men with a moustache, beard or sideburns, seborrhoeic dermatitis may involve these areas, and it resolves if these areas are shaves (1).
There is often an associated blepharitis or otitis externa. Secondary infection with Candida in the intertriginous areas is common.