A simple but yet novel stain in the diagnosis of onychomycosis

Abstract

Background: Onychomycosis can resemble other nail dystrophies and hence the clinical diagnosis should be supplemented with a laboratory diagnosis. Rapid diagnosis of onychomycosis is the necessary to initiate early therapy. In this study, the efficacy of Chicago Sky Blue (CSB) stain in comparison with that of routine potassium hydroxide (KOH) preparation in the diagnosis of onychomycosis was evaluated. Methods: A prospective study of 42 nails with a clinical diagnosis of distal lateral subungual onychomycosis. KOH mount followed by direct microscopic examination of the subungual debris was performed. This was followed by microscopic examination after addition of 1% CSB. Results were interpreted by two experienced dermatologists. Results: 18 (42.9%) nails showed KOH positivity and 37 (88.1%) were positive for CSB stain. Conclusions: CSB staining was more sensitive and was more accurate in the rapid diagnosis of onychomycosis. Colour contrast provided by the CSB made it easier identification of fungal elements.