Unilateral linear lichen planus with mucous membrane involvement.

Linear lichen planus is a rare distinctive variant of lichen planus (LP) characterized by a pruritic eruption of lichenoid, violaceous papules in a linear distribution that sometimes assume a Blaschko line pattern. We describe a 33-year-old woman who presented with a 4-month history of a slightly pruritic unilateral linear array of papular lesions on the left side of her neck that were clinically and histologically consistent with linear LP. Two months after the onset of her skin disease she developed typical lesions with a lacy white pattern on the left lateral aspect of her tongue and the left buccal mucosa with a striking predominance for the left side. Clinically the lesions on the patient's neck were similar to lichen striatus or lichenoid epidermal naevus, a variant of linear verrucous epidermal naevus. However, the histological features and the fact that later in the course of her disease the patient developed typical LP of the oral mucosa suggest that this patient has the rare condition of linear LP with unilateral restriction.