Background: Erythrasma is an uncommon vulvar infection, best diagnosed by its fluorescence under the Wood lamp. This report shows that despite a negative Wood lamp examination, the diagnosis can be made histologically.
Case: A 42-year-old woman was referred to our clinic with a persistent candidal infection. Evaluation included a Wood lamp examination, wet mount, and potassium hydroxide test of the affected skin, all of which were negative. A biopsy of the area demonstrated rods and filamentous organisms in the keratotic layer consistent with a Corynebacterium minutissimum infection. The patient was diagnosed as having erythrasma, and she responded to oral erythromycin.
Conclusion: Persistent vulvar diseases may be caused by erythrasma despite a negative Wood lamp examination. The diagnosis can be made by biopsy of the lesion.