Failure of drug rash to appear in a previously irradiated site

Leukocytoclastic vasculitis sparing a tattoo with halo effect

“…Here we report, to our knowledge, an unusual case of LCV with sparing of tattooed skin to produce a “halo.” The phenomenon of one skin disease sparing the site of a previous skin condition has been recognized since 1981, when Cochran and Wilkin 3 reported a case of a drug rash failing to appear in a previously irradiated site on a 12-year-old girl. Since then, various related terms have been used to describe this phenomenon, including the reverse Koebner phenomenon (nonappearance or disappearance of skin lesions at sites of trauma) 4 and Wolf's isotopic nonresponse (absence of a cutaneous eruption at the site of another unrelated and already healed skin disease).…”

The Sparing Phenomenon. A case series of the inverse Koebner and related phenomena

“…Failure of a drug eruption to occur in a site that had undergone irradiation was the first documented sparing reaction in the literature [2]. Since then, non-existence of various forms of drug reactions in an areas previously subjected to an insult has been reported.…”

“…Since then, non-existence of various forms of drug reactions in an areas previously subjected to an insult has been reported. Ampicillin and clotrimaxazole-trimethopim were the most noted culprits [2,3,9]. An area subjected to herpes zoster was the often resistant site for the many diseases including leprosy and CTCL [10][11][12][13].…”

“…The effect of ionizing radiation on cutaneous blood vessles that resulted in a reduced activity of blood vessles wall, a diminished vascular bed and reduced carriage of constitute agents to the affected site, and there by none existing of drug rash over the radiation portal was explained by Cochran and Bernhart et al [2].…”

“…In contrast to this well-known observation in which skin disease is produced in the site of trauma, infrequently disease may be spared in the site of trauma. Cochran and colleagues in 1981 first described a macular papular drug reaction which spared the sites of previous X-irradiation in a patient with had been treated for Wilm's tumor [2]. Bernhard et al later introduced the term "Koebner non reaction" or "Isomorphic nonresponse" to refer the absence of a drug reaction the at site of the previous x-irradiation [3].…”