Lichen planus occurring on radiotherapy site: a case report

Abstract

Lichen planus (LP) is an inflammatory skin condition characterized by the presence of pruritic, polygonal, purple flattopped papules and plaques typically symmetrically distributed. The occurrence of these lesions could be attributed to the isomorphic response of koebner occuring regularly in LP. A 38-year-old woman developed pruritic purplish papules spread on a brown lichenoid patch over the left chest area 3 months after radiation therapy for an invasive carcinoma of the left breast. These lesions were confined to the radiation therapy site. Almost any type of irritant can provoke the isomorphic response including traumatisms, friction, infection and ultraviolet light. Only few cases of LP confined to radiation site have been described so far.