By Gary M. White, MD
Pityrosporum folliculitis (PF) is an infection of the hair follicle by the fungus Malassezia furfur, formerly known as Pityrosporum ovale. This condition is often associated with seborrheic dermatitis, which is not surprising since both are caused by Malassezia furfur. Some have called it Malassezia folliculitis. Predisposing conditions include hot, humid environments, excessive sweating, immunosuppression, corticosteroid or antibiotic use, adolescence, male gender, and transplantation. Associated diseases include steroid folliculitis, acne, and tinea versicolor.
Multiple follicular pustules and erythematous papules on the upper back and/or chest and shoulders is characteristic. Some reports have highlighted facial involvement as being present in more than half of patients. The sides of the face and chin are preferred as opposed to the central face. Some women have noted a flare with their menstrual cycle. The lesions may be intensely itchy.
PF may be misdiagnosed as acne and vice versa. Acne has comedones whereas PF does not. Some patients have developed PF after beginning a tetracycline for acne [zeit fur Haut1997;72;928]. Bacterial folliculitis will respond to oral antibiotics. Steroid acne/folliculitis probably represents PF. In the case of PF, Wood's light may show a yellow-green fluorescence in 2/3 of cases. KOH may be employed, but caution exercised as Pityrosporum is part of the normal flora.
Of course a biopsy (punch) with PAS staining to visualize the Pityrosporum species may be needed in difficult cases. A trial of an oral antifungal agent, e.g., itraconazole, which if rapidly effective, may be the easiest way to establish the diagnosis.
Oral itraconazole and fluconazole (for 3 weeks) may be given if necessary although rapid relapse is common. Itraconazole 200 mg/day x 7 days-1 month is typical. Fluconazole 400 mg po once may be used. One patient of mine has done well with itraconazole 100 mg QD for 7 days every 1-2 months.
Selenium sulfide 2.5% or ketoconazole 2% shampoo lathered on the scalp and trunk for 5-10 minutes QD initially and then tapered is usually effective. One may have the patient use a soap containing 2% zinc pyrithione (ZNP bar). Zinc pyrithione has activity against M. furfur. Topical clotrimazole cream has been employed.
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