It is well known that in lichen planus, as in certain other diseases, there is a tendency for lesions to develop in areas which have been subject to trauma and other insults. Thus, this isomorphic (Koebner) phenomenon in lichen planus may be manifested for example, in a scratch, burn, or in an area subjected to roentgen or thorium-X radiation.1 In addition, lichen planus has been seen in a linear or systematized form without a history of a known preceding insult, following the course of a peripheral nerve, a vein, or Langer's and Voigt's lines.2
Lichen planus occurring in the site of a previous zoster eruption has only rarely been reported. Gougerot and Filliot,3 in 1929, described a case of lichen planus which developed in a scar of zoster of 2-months' duration. In addition to the typical zosteriform lichen planus, the patient also presented lesions of lichen spinulosus