Dermoscopic findings of fungal melanonychia

There are very few studies about dermoscopic findings of fungal melanonychia (FM) apart from the case reports.

To reveal and identify dermoscopic findings which facilitate diagnosis of the FM.

The study included a total of 42 nails from 33 patients diagnosed with FM on the basis of the clinical history, physical examination, dermoscopic findings and microbiological investigation. All of the dermoscopic images were retrospectively reviewed and the findings identified were recorded in a period of 1 year.

The most common presentation was homogenous brown pigmentation (n = 15, 35.7%). The other presentations included: homogenous black (n = 9, 21.4%), homogenous grey (n = 9, 21.4%), clumped/granular black (n = 7, 16.6%) and irregular longitudinal black (n = 4, 9.5%) pigmentation. Superficial transverse striation was observed in 11 (26.1%) nails. Twenty (47.6%) nails showed white streaks (white longitudinal striae) and 6 (14.2%) nails showed distal white jagged edge (also known as "spikes"). Twenty-two (52.3%) nails had at least one of white streaks and jagged edge findings. 4 (9.5%) nails showed pseudo Hutchinson's sign.

To the best of our knowledge, this is the most comprehensive study regarding the dermoscopic patterns of FM. Here, we also evaluated onychomycosis associated dermoscopic findings like white longitudinal striae and jagged edges. Our study, along with the previous studies, showed that dermoscopy can be a very helpful method in the diagnosis of FM. Long disease duration, homogenous pigmentation pattern, presence of white streaks and jagged edges are the main clues to FM.