The term covers at least three common patterns of eczema, mainly affecting hairy areas, and often show-ing characteristic greasy yellowish scales. These pat-terns may merge together (Fig. 7.19).
1. A red scaly or exudative eruption of the scalp, ears (Fig. 7.20), face (Fig. 7.21) and eyebrows. May be associated with chronic blepharitis and otitis externa.
2. Dry scaly ‘petaloid’ lesions of the presternal(Fig. 7.22) and interscapular areas. There may also be extensive follicular papules or pustules on the trunk (seborrhoeic folliculitis or pityrosporum folliculitis).
3 Intertriginous lesions of the armpits, umbilicus or groins, or under spectacles or hearing aids.
This condition is not obviously related to seborrhoea. It may run in some families, often affecting those with a tendency to dandruff. The success of treatments directed against yeasts has suggested that overgrowth of the pityrosporum yeast skin commensals plays an important part in the development of seborrhoeic eczema. This fits well with the fact that seborrhoeic eczema is often an early sign of AIDS, and that it responds to antiyeast agents such as topical ketocona-zole shampoo or cream.
Seborrhoeic eczema may affect infants (Fig. 7.23) but is most common in adult males. In infants it clears quickly but in adults its course is unpredictable and may be chronic or recurrent. Some particularly severe cases have occurred in patients with AIDS (Fig. 14.35).
May be associated with furunculosis. In the intertriginous type, superadded Candida infection is common.
None are usually needed, but bear possible HIV infection and Parkinson’s disease in mind.
Therapy is suppressive rather than curative and patients should be told this. Topical imidazoles are perhaps the first line of treatment. Two per cent sulphur and 2% salicylic acid in aqueous cream is often helpful and avoids the problem of topical steroids. It may be used on the scalp overnight and removed by a medicated shampoo, which may con-tain ketoconazole, tar, salicylic acid, sulphur, zinc or selenium sulphide. A topical lithium preparation may help the facial rash. For intertriginous lesions a weak steroid–antiseptic or steroid–antifungal combination is often effective. For severe and unresponsive cases a short course of oral itraconazole may be helpful.