Isomorphic response after saphenectomy in a patient with granuloma annulare.

Physical trauma has been reported as an etiologic factor of granuloma annulare, resembling a Koebner phenomenon. Moreover, granuloma annulare frequently arises at the same location of a previously healed, unrelated skin disease, mainly herpetic infection. These data seem to suggest that granuloma annulare might be a peculiar pattern of skin reaction to different stimuli, either physical or biologic, in predisposed subjects. In the case reported herein, the onset of a typical lesion of granuloma annulare at the site of saphenectomy might be explained as the result of an aberrant wound healing process, with release, by keratinocytes and/or Langerhans cells, of lymphocyte-derived chemotactic cytokines, capable of promoting the development of the granulomatous lesion.