Evaluation of wood s light and direct smear for diagnosis of pityriasis versicolor and erythrasma
Maleki, M.; Fata, A.
Saudi Medical Journal 26(9): 1483-1484
2005
ISSN/ISBN: 0379-5284 PMID: 16155681 Document Number: 588256
215 individuals with skin lesions suspected to be pityriasis versicolor (n=88) or erythrasma (n=127) were examined at the Departments of Mycology and Dermatology, Emam Reza Hospital, Mashhad, Iran, over a 16-month period (September 2003-December 2004). All patients were tested by Wood's light in a dark room. Fresh smear by potassium hydroxide was prepared for diagnosis of pityriasis versicolor, and direct stained smear by methylene blue for erythrasma. Among 88 patients suspected to have pityriasis versicolor, 55 (62.5%) showed positive golden yellow fluorescence under Wood's light, while 59 (67%) had positive direct smear for Malassezia furfur. Among 127 patients suspected to have erythrasma, 38 (29.9%) showed positive orange-red fluorescence under Wood's light, while 40 (31.5%) had positive direct stained smear for Corynebacterium minutissimum. Statistical chi-square test showed no significant difference between Wood's light and the other methods. It is concluded that the Wood's light test is a valuable method for diagnosis of pityriasis versicolor and erythrasma.