Failure of flat warts to recur in electrosurgically altered skin.

Two men with recurring flat warts in the beard area have been observed for five and ten years, respectively. Both have depigmented patches at sites where flat warts had been removed by electrosurgical destruction. Crops of new warts appear periodically. These develop always on the normally pigmented skin and have never been found in the leukodermic areas. Flat warts have been observed repeatedly at the margin of depigmented and normal skin; these invariably enlarge toward the normal skin and never encroach on leukodermic skin. The failure of flat warts to develop in electrosurgically treated skin, if substantiated, would indicate that local tissue factors influence resistance to development of flat warts. Perhaps this phenomenon is similar to that reported in Darier's disease, where partial-thickness excision of involved skin has resulted in resistance to recurrent disease.