The Study on the Incidence of Pityriasis Versicolor of the Scalp in a Normal Person and Patients with Seborrheic Dermatitis / 대한피부과학회지

ABSTRACT

BACKGROUND: Pityrosporum yeast is a normal resident flora of the skin. Its hyphal form can be found on the lesions of pityriasis versicolor. Our previous studies showed that pathogenic pityrosporal hyphae coulc be found on a clinically normal scalp. We called it pityriasis versicolor of the scalp. This species may be involved in the pathogenesis of seborrheic dermatitis. OBJECTIVE: We investigated the incidence of pityrosporal hyphae on the scalp of patients with seborrheic dermatitis and normal persons, and compared the results between the two groups. METHODS: 202 patients with seborrheic dermatitis, 350 normal persons were studied. Scalp scrapings were stained with 20% Parker ink-KOH(P-KOH) solution. The number of pityrosporal hyphae per high power field(x 400) were counted according to a grading method(1+ to 3+). RESULTS: The incidence of pityriasis versicolor of the scalp was 28.7% in patients with seborrheic dermatitis, and 21.7% in normal persons. However the incidence of pityriasis versicolor of the scalp in seborrheic dermatitis in the age group of the second and sixth decades was two fold higher, 43.3%, 40.9%, respectively than in the normal control groups, from 9.5% to 25.0%. In the case of sex distribution, the incidence of pityriasis versicolor of the scalp in female patients of seborrheic dermatitis was two fold higher, 34.8%, than in the normal control, 18.8%. According to seasonal variation, the incidence was higher in spring(21.7%) and summer(34.3%) in the control group, and higher in spring, fall and summer, 31.2, 31.4 and 39.2%, respectively, in people with seborrheic dermatitis. CONCLUSION: The results of this study showed that the incidence of pityriasis versicolor of the scalp in patients with seborrheic dermatitis and normal person is similar, There were, however some differences between them according to age, sex and season.