Lichen Striatus and Lines of Blaschko
A 3-year-old boy presented with a 3-week history of a V-shaped rash on his back (Panel A). On the basis of the acute appearance and typical blaschkoid distribution of the rash, lichen striatus was diagnosed. Lichen striatus is a benign, self-limited, linear inflammatory skin condition that follows the lines of Blaschko. Usually diagnosed clinically, lichen striatus may require a biopsy in cases of uncertainty. Histologic findings show lichenoid, lymphocytic infiltrate with overlying epidermal acanthosis, dyskeratosis, hyperkeratosis, occasional parakeratosis, and lymphocytic exocytosis. Although most physicians are skilled at recognizing dermatomal borders, few are aware of the lines of Blaschko. These lines represent pathways of epidermal-cell migration and proliferation during fetal development and reflect the existence of cutaneous mosaicism (Panel B). Many skin eruptions, including certain epidermal nevi, linear psoriasis, linear morphea, and linear cutaneous lupus erythematosus, may follow the lines of Blaschko. Given the self-limited course of lichen striatus, the family decided to observe the child. At a 4-month follow-up visit, the rash was still unresolved.
Application of high potentially steroids locally have some benefit.