The Study on Incidence of Pityrosporosis of the External Ear Canal between Normal Persons and Patients with Seborrheic Dermatitis

Kim, Cheon Gi; Kwon, Kyung Sool; Jang, Ho Sun; Chung, Tae Ahn

Abstract

BACKGROUND: Pityrosporum yeast is a resident microflora of the normal skin and abundant in seborrheic dermatitis. In pathologic conditions, pityrosporum yeast is converted into hyphal form. Previous studies showed that this hyphal form could be found on clinically normal skin too.
OBJECTIVES
We compared the incidence of Pityrosporum infection of the external ear canal in normal controls with that in patients with seborrheic dermatitis.
METHODS
Seborrheic dermatitis, 258 subjects and normal person, 362 subjects were studied. Ear wax specimens were stained with 20% Parker ink-KOH(P-KOH) solution. The number of pityrosporal hyphae were graded according to hyphal index(1+ to 3+).
RESULTS
The incidence of Pityrosporum infection of the external ear canal is 28.7% in patients with seborrheic dermatitis and 24.6% in normal controls, Amounts of pityrosporal hyphae are similar between two groups too. According to age group, incidence of PV of the external ear canal in patients with seborrheic dermatitis is statistically significantly higher than in normal controls. Female with seborrheic dermatitis have more Pityrosporum infection of the external ear canal than normal female controls. Pityrosporum infection of the external ear canal in patients with seborrheic dermatitis is prevalent in summer and spring in contrast to normal controls who have high incidence in spring. Among patients with Pityrosporum infection of the external ear canal, asymtomatic cases amount up to 70%.
CONCLUSION
The results of this study showed that the incidence of Pityrosporum infection of the external ear canal in patients with seborrheic dermatitis and normal person is similar, but according to the age, sex and season, there were some differences between two groups.