By Gary M. White, MD
Note the redness and scale in the T-zone.
Seborrheic dermatitis (SD) is akin to bad dandruff. It is common with a peak in men 20-50 years of age. It appears to be caused by an immune response to the overgrowth of the fungus Malassezia.
While the hair is normal, the scalp is scaly and mildly red. Many people not only have seborrheic dermatitis of the scalp, but have it on the face as well. It particularly likes the eyebrows and along the sides of the nose and the ears. A red, scaly rash of the mid chest in a hairy man may occur. Occasionally, the folds of the axilla may become involved. The patient commonly complains, "My scalp itches." A mild, diffuse loss of hair may occur. Darkening of the seborrheic areas has been termed seborrheic melanosis.
For many patients who shampoo infrequently, shampooing more frequently, e.g., daily, is sufficient. For those who need more, shampooing with a medicated shampoo ("medicated" means "kills fungus") is needed. Options include 2% ketoconazole (by prescription) or OTC shampoos zinc pyrithione, selenium sulfide, or tar depending upon patient preference. Lather the scalp, face, and any other involved areas daily or every other day initially. Once control is achieved, use may be tapered to 1-3 times per week.
Specific instructions for ketoconazole shampoo, which may be followed for all medicated shampoos, is as follows:
"The infected parts of the skin should be washed with NIZORAL Shampoo 2%, allowing the product to soak in for 3 to 5 minutes before rinsing. The skin itself should be thoroughly washed, not just the hair." [source Package Insert].
Although the usual recommendation is to use ketoconazole 2% shampoo 2-4 times a week, it may be safely used daily, as has been reported as an adjunctive treatment for tinea capitis [Int J Dermatol. 2000 Apr;39(4):302-4].
Patients with darker skin may need to shampoo less often because of their hair. They may, for example, only be able to shampoo once a week.
Most patients--especially those with pruritus--need a topical steroid, usually liquid for the scalp and cream for the face. Typical choices are clobetasol solution QD-BID to affected areas of the scalp and desonide cream QD-BID to the face. Hydrocortisone OTC may be sufficient for the face.
Pimecrolimus cream or tacrolimus ointment QD-BID to the face is an alternative to a topical steroid. For example, tacrolimus ointment daily to the face for 2 weeks to clear and then twice-a-week maintenance is usually successful.
Although rarely needed, itraconazole 200 mg/day x 7 days or fluconazole 300 mg weekly has been shown to be effective [Dermatol Res Pract. 2014;2014]. Oral ketoconazole should NOT be given due to the risk of liver toxicity.
For seborrheic dermatitis of the ear canal, a mild to moderate topical steroid lotion or cream (e.g., desonide, triamcinolone) may be used daily initially and then 2-3 times a week as needed.
A topical steroid liquid, e.g., triamcinolone lotion/solution, is helpful.
Pimecrolimus cream is very nice here as there is no concern about atrophy. Otherwise a low-potency topical steroid, e.g., desonide cream, may be given.
Oral isotretinoin 10 mg every other day significantly reduced the signs and symptoms of SD in one study [Online, Oct. 25 in the International Journal of Dermatology]. Women of childbearing potential should not be considered for this therapy because of the teratogenicity of isotretinoin.
Typical SD of the chest.
Petaloid seborrheic dermatitis of the chest.
Annular rings in a darker skinned patient.
Note the significant postinflammatory hypopigmentation in this darker-skinned patient.
Seborrheic dermatitis of the folds of the neck.
Seborrheic dermatitis of the forehead and eyebrows and a basal cell carcinoma.
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