The role of dermoscopy in the diagnosis of distal lateral subungual onychomycosis

Recently dermoscopic patterns, that can be useful in the diagnosis of distal and lateral subungual onychomycosis, were identified. In this study, we aimed to determine the frequency of the defined patterns so far and additionally to identify other patterns that were observed and to investigate the place of these patterns in the diagnosis of Distal Lateral Subungual Onychomycosis (DLSO) in the dermoscopic examination of the patients with pre-diagnosis of DLSO. Patients admitted dermatology outpatient clinic of Haydarpasa Numune Training and Research Hospital with the complaint of nail disturbance suspicious for DLSO (97 patients) between the August 2015 and February 2016. Clinical and dermoscopic photographs of the cases with a pre-diagnosis of DLSO were taken and their nails were cut for pathological examination and culture. In hematoxylin and eosin, and periodic acid schiff examination, hyphe and/or spore were observed in 134 (65.4%) and fungal growth was detected in 99 (48.3%) of the nail samples. As a result of logistic regression model analysis, the p values of the ‘ruin appearance’, ‘homogeneous leukonychia’, ‘punctate leukonychia’, and ‘black discoloration’ patterns preserved their statistical significance (p = 0.015, p = 0.009, p = 0.026, p = 0.040, respectively). We believe that in nail disorders clinically resembling DLSO patients, the presence of dermoscopic patterns of ruin appearance, homogenous leuconychia, punctate leuconychia, and black discoloration strongly supports the clinical diagnosis of DLSO.