Lichen planus occurring in narrow lines, although comparatively rare, has been recognized for a number of years. The condition was known to Cazenave and Devergie as "lichen en ruban" as early as 1843. In most of the cases, since reported, the eruption has apparently followed the course of a cutaneous nerve, especially the small sciatic. Examples of this distribution have been presented to the London Dermatological Society by Crocker, Morris, Pringle and Galloway.
A few cases, however, have been reported in which the eruption followed the courses of other nerves. In one of Mackenzie's cases it followed that of the left ulnar and internal cutaneous nerves and in another it began in the course of some of the intercostal nerves, subsequently becoming general.
More rarely the linear eruption has not apparently followed a nerve, as in Meyer's case in which it was supposed to have followed Voight's lines and in