Comparison of diagnostic methods in onychomycosis

Abstract

Aim: Onychomycosis is a chronic fungal infection of the nail bed, plate, or matrix. This study aimed to compare the sensitivity of three diagnostic methods in the diagnosis of onychomycosis. Material and Method: This study included 39 patients with a clinical diagnosis of onychomycosis of the toenails, who presented to Medipol Mega University Hospital between May 2019 and August 2022. Using the nail samples taken from the patients, the results of the direct microscopic examination with standard potassium hydroxide (KOH), histopathological examination performed with periodic acid-Schiff (PAS) staining, and fungal agents that grew in fungal culture were noted. Results: Eleven (28.2%) patients were female, and 28 (71.8%) were male, with the mean age being 43.1±13.9 years. Of the patients, 53.8% had distal subungual onychomycosis and 46.2% had total subungual onychomycosis. The mean disease duration was 38.8±24.5 (12-120) months. Fungal infection was detected on direct microscopic examination with standard KOH in 66.7% of the patients, culture growth in 38.5%, and PAS staining on histopathological examination in 71.8%, and the sensitivities of these methods were determined as 74.3%, 49.2%, and 80%, respectively, with the negative predictive values being 30.8%, 16.7%, and 36.4%, respectively. Conclusion: Among the investigated methods, histopathological examination with PAS staining was found to have the highest sensitivity and negative predictive value in the diagnosis of onychomycosis.