ABSTRACT
Lichen striatus is a benign, usually unilateral, linear dermatosis typically affecting children. It is a cutaneous mosaicism caused by a postzygotic somatic mutation—there is tolerance until a triggering event induces a self-limiting autoimmune T lymphocyte inflammatory reaction. When the nails are affected, typical classic lichenoid nail changes are easily detectable, more often limited to only one portion of the nail or to a single nail plate. It is common to see longitudinal fissuring, onychorrhexis, onycholysis, and subungual hyperkeratosis. Flesh-colored or slightly red flat-topped papules following Blaschko's lines may be associated. The main differential diagnoses are nail lichen planus, nail lichen nitidus, linear nail psoriasis, linear keratosis follicularis, and Inflammatory linear verrucous epidermal nevus (ILVEN). Dermoscopy is an important tool for the diagnosis, but not pathognomonic ( Figures 13.1 and 13.2 ).
