Nail lichen striatus: is dermoscopy useful for the diagnosis?

Background/objectives: Lichen striatus is a unilateral inflammatory dermatosis that rarely affects the nail unit. When the inflammation involves the nail unit, classic lichenoid nail changes are easily detectable, more often limited to only one portion of the nail. Usually the nail dystrophy coexists with periungual skin papules following Blaschko's lines, but it could also be an isolated feature. Because a nail unit biopsy presents difficulties in execution, especially in a child, the aim of our study has been to describe the nail unit dermoscopy features of lichen striatus hoping to provide a valid aid to clinicians in the diagnosing this rare disorder. Methods: We reviewed the images of five pediatric patients with a clinical diagnosis of lichen striatus. Data about sex, age, localization, predisposing/triggering factors, and associated disorders are reported. Results: The diagnosis of lichen striatus can be challenging as there are clinically overlapping features with related dermatoses. A common diagnostic pitfall occurs with inflammatory linear verrucous epidermal nevus and lichen planus. Involvement of only one part of the nail plate with linear longitudinal fissuring, ridging, and distal splitting, especially if seen with perionychial skin lesions, is characteristic of lichen striatus. Conclusions: Nail lichen striatus is rare, and there is sparse published literature on it. When the changes in lichen striatus are limited to the nail, the diagnosis may easily be missed. We therefore believe that dermoscopy is an important diagnostic maneuver, which should be integrated into the evaluation of patients with potential lichen striatus, and in particular is helpful for clinicians unwilling or unable to perform a nail unit biopsy.