Significance of Hair Follicle Mite Examination by Skin Surface Biopsy in Disease Associated with Hair Follicle Mite / 대한피부과학회지

ABSTRACT

BACKGROUND: The pathogenic role of the hair follicle mite in rosacea is still a matter of debate. Although the hair follicle mite may induce a pathologic condition by dermal invasion or excessive number of mites, the number of mites necessary to induce a pathologic condition has not been established in Korea. OBJECTIVE: The purpose of our study was to know the causative role of the hair follicle mite in rosacea and the threshold value between 'normal' and 'abnormal' density of the hair follicle mite on Korean facial skin. METHODS: We applied skin surface biopsy to investigate the population density and distribution of hair follicle mites in the facial skin of 50 patients with rosacea (9 with episodic erythema, 29 with stage I, 12 with stage II), 7 patients with demodicidosis and 54 control subjects. The mites were counted in measured skin surface biopsy specimens obtained from three standard facial sites(2cm on cheek and chin, 1cm on nose) with cyanoacrylate glue. RESULTS: 1. The mean mite count per 5cm was 3.4+/-0.7 in control subjects and 10.7+/-1.9 in patients with rosacea(p<0.05) The density of Demodex(mite count/ 5cm) was significantly higher in patients with demodicidosis (115+/-14.2) than in the control (p<0.001) and rosacea patients(p<0.05). 2. The highest density of mites was found on the cheek in the control and diseased subjects. The incidence of hair follicle mites was higher on the nose than on the cheek in the control subjects and rosacea patients. In demodicidosis, the incidence of the hair follicle mites was higher on the cheek than on the nose. 3. The distribution of hair follicle mite was not significantly different among the three clinical stages of rosacea. The mite counts in stage II rosacea were higher than those of control subjects (p<0.05). 4. The distribution of the hair follicle mite in the control subjects was related to a increase of age but not related to sex. The distribution of the hair flooicle mites in rosacea patients was not related to age or sex. 5. Hair follicle mites were found in 33 out of 54 control subjects(61%) and in 40 out of 50 rosacea patients (80%). The mite counts of all control subjects and all rosacea patients were less than 5/cm and 10/cm, respectively. The mite counts of all demodicidosis patients were more than 10/cm. CONCLUSION: These results suggest that the increased nomber of mites play a part in the pathogenesis of rosacea and demodicidosis is a specifio disease entity differentiated from rosacea. When the density of the hair follicle mites is above 5 /cm2, a pathologic condition of the skin, such as rosacea and demodicidosis, would have to be considered. Demodicidosis should be suspected when the density of the hair follicle mites is above 10 /cm. In addition, skin surface biopsy is recommended as the most simple and useful clinical method in search of the distribution of the distrbution of the hair follicle mites.