Pityrosporum(Malassezia) Related Diseases Especially Seborrheic Dermatitis

Sei, Yoshihiro; Oshima, Ayumu; Nakabayashi, Atuhiro; Hamaguchi, Taizo; Ninomiya, Junya; Iizuka, Takasi

Abstract

The cause of seborrheic dermatitis is unknown, although many attempts have been made to relate it to infection with bacteria or with ,Malassezia furfur. Recently, there have been many studies concerning the efficacy of anti-fungal agents against seborrheic dermatitis. In this occasion, I introduce the result of studies concerning the efficacy of antimycotic drugs against dandruff and seborrheic dermatitis in Japan and in our outpatient clinic of dermatology. I also report the results of our laboratory studies concerning the mechanism of seborrheic dermatitis. We produced the animal models of seborrheic dermatitis. Lesions in immunized guinea pigs developed faster than those of non immunized guinea pigs. The anti-Malassezia IgY seems to delay the development of the lesion. Malassezia spores were detected from lesional skin by direct light microscopy method in our outpatient clinic. Approximately 85% of the facial sites and 75% of the scalp sites were positive in total. One of our clinical studies was a double-blind, comparative study conducted at 8 institutions on the usefulness of shampoo containing 0.75% miconazole nitrate (MZS) for the treatment of dandruff. Shampoo vehicle (BSS) without the reagent served as the control. MZS was evaluated as useful in 34 of the 58, and BSS in 19 of the 50 subjects, thus MZS was significantly more useful than BSS (p=0.020). The other clinical study concerned on the efficacy of ketoconazole cream used in 168 patients for the treatment of seborrheic dermatitis. This study was done as an open trial by multiple institutes. Approximately 80% evaluated as effective, in total. In 23 valuable cases, fungus disappeared in 16 cases (69.6%). It is concluded that anti-fungal agents have potential value as a new therapeutic agent -an alterative to steroids- for the treatment of seborrheic dermatitis.