Dermatoscopic Features of Onychomycosis and its Correlation with Nail Plate Potassium Hydroxide Mount (KOH), Culture, and Periodic Acid Schiff Stain (PAS) in North East India

CONTEXT: Dermatoscopy has been used recently for identifying the specific features of onychomycosis. Very few studies have used it as a diagnostic tool. Our study highlights the specific patterns in different clinical types of onychomycosis and the novel features that have never been reported previously. AIMS: To study the dermatoscopic patterns in patients with onychomycosis and determine the sensitivity, specificity, positive, and negative predictive values of the different features. STUDY DESIGN: A cross-sectional study. MATERIALS AND METHOD: Dermatoscopic picture using dinolite video dermatoscope was taken in patients diagnosed with onychomycosis either with a positive KOH, culture, and/or PAS. RESULT: A total of 80 patients were included. Onychomycosis was identified in 68 individuals. Clinically, 73.52% presented with distal lateral subungual onychomycosis (DLSO) and 26.47% had total dystrophic (TD). PAS was positive in 85.29% of patients, KOH in 75%, and culture in 66.17%. Trichophyton species were isolated in 53.33%, whereas Candida species in 40% of patients. Dermatoscopic features were seen in all 68 patients (100%). The most common finding in decreasing order includes spike pattern, ruin appearance, distal irregular terminations (DIT), longitudinal striations, chromonychia, focal homogeneous opacities, microsplitting, and uniform homogeneous pattern. Three novel patterns were observed: homogeneous opacity with a-z pattern border, microsplitting in a Christmas tree pattern, and focal homogeneous opacities. CONCLUSION: To our knowledge, this is the first study conducted in northeast India where dermatoscopy was used as a diagnostic tool and it was found to have the highest sensitivity. New features that have not been described before have been identified.