Introduction
Seborrhoeic dermatitis in adults is a chronic dermatitis thought to be caused by an inflammatory reaction related to a proliferation of a normal skin inhabitant, a fungus called Malassezia furfur (formerly known as Pityrosporum ovale). It is common, affecting around 2% of the general population.
Epidemiology
- Incidence: 500.00 cases per 100,000 person-years
- Peak incidence: 30-40 years
- Sex ratio: more common in males 2:1
| Condition | Relative incidence |
|---|---|
| Seborrhoeic dermatitis in adults | 1 |
| Periorificial dermatitis | 0.40 |
| Rosacea | 0.33 |
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Aetiology
Associated conditions include
- HIV
- Parkinson's disease
Clinical features
Features
- eczematous lesions on the sebum-rich areas: scalp (may cause dandruff), periorbital, auricular and nasolabial folds
- otitis externa and blepharitis may develop
Management
Scalp disease management
Face and body management
- over the counter preparations containing zinc pyrithione ('Head & Shoulders') and tar ('Neutrogena T/Gel') are first-line
- the preferred second-line agent is ketoconazole
- selenium sulphide and topical corticosteroid may also be useful
Face and body management
- topical antifungals: e.g. ketoconazole
- topical steroids: best used for short periods
- difficult to treat - recurrences are common