Background: Erythrasma is a superficial skin infection caused by Corynebacterium minutissimum . Interdigital erythrasma is the most common form and is easily confused with tinea pedis. The aim of this study was to determine the prevalence of interdigital erythrasma in patients with clinically suspected tinea pedis.
Methods: This study was performed between January 1, 2011, and January 31, 2012. It included 182 patients who presented with concerns about interdigital lesions. All of the patients were examined with a Wood's lamp, and smears were stained with Gram's method. Direct examination with 20% potassium hydroxide was performed.
Results: Of 182 patients with interdigital lesions, 73 (40.1%) were diagnosed as having erythrasma. The mean ± SD age of the patients with erythrasma was 45.52 ± 10.83 years (range, 22-70 years). Most of the patients with erythrasma were women (56.2%). The most often clinical finding was desquamation. Using only Wood's lamp examination or Gram's staining resulted in 31 (42.5%) or 14 (19.2%) positive patients, respectively. Using Wood's lamp examination and Gram's staining concurrently resulted in 28 positive patients (38.4%).
Conclusions: Interdigital erythrasma is a common condition and can be difficult to differentiate from tinea pedis. Simple and rapid diagnosis can be made with Wood's lamp examination, but Gram's staining is also a useful method, especially in patients with negative Wood's lamp examination findings.