Accurate diagnosis of onychomycosis is important since misdiagnosis can lead to inappropriate therapy, delayed diagnosis of other nail conditions, and antifungal resistance. Dermoscopy is an emerging diagnostic tool, particularly valuable in the resource-poor settings.

The study aimed to evaluate the accuracy of dermoscopy as a point-of-care tool in diagnosing distal subungual onychomycosis (DSO) at a tertiary hospital.

An observational, prospective, and cross-sectional study was conducted among 22 clinically diagnosed DSO patients using convenience sampling at a tertiary hospital from November 2019 to September 2021.

Participants underwent gross nail examination, dermoscopy, potassium hydroxide (KOH), and periodic acid-Schiff (PAS) examinations.

Sensitivity, specificity, predictive value, and likelihood ratios (LRs) of the dermoscopic patterns were obtained using KOH and PAS results as the reference standard.

Fifty-one nails were submitted but 2 were lost during the processing, leaving 49 nails for analysis. The most common pattern was jagged edge with spikes (65.3%). Individual patterns yielded only low-to-moderate sensitivity (32.4%–73.5%). However, combining all patterns increased sensitivity to 91.2% (95% confidence interval: 76.3–98.1). Ruin appearance showed the highest specificity (100%) and positive predictive value (100%). LRs were not significant enough to draw the conclusions.

Dermoscopy may serve as an on-site, adjunct tool in the diagnosis of DSO, especially when the combination of patterns is considered. Ruin appearance maybe particularly useful in ruling in DSO. However, confirmation using mycological and histopathological tests remains essential.