Retrospective single-center study evaluating clinical and dermoscopic features of longitudinal melanonychia, ABCDEF criteria, and risk of malignancy.

In the cases of LM in which biopsy was performed, SUM usually presented with a wider band and greater width percentage than benign LM did. The number of ABCDEF criteria met was not different between the groups. Because many of the clinical and dermoscopic signs were less consistent, biopsy should be performed in cases with any concerning band, especially in those with width percentage higher than 40%.