[Amoxicillin-induced skin rash sparing a plaque of erythema migrans: Renbök phenomenon: Case report and literature review].

INTRODUCTION

Renbök phenomenon describes the inhibition of a lesion when a different one appears. We describe the first case of Renbök phenomenon occurring in a context of erythema migrans (EM) spared by an amoxicillin-induced skin rash and we also present a literature review.

CASE REPORT: A 60-year-old patient was treated with amoxicillin for EM on the right knee and subsequently developed generalized erythema as a result of an antibiotic-induced skin rash, with sparing of the area previously affected by EM. Renbök phenomenon was diagnosed.

DISCUSSION: In 1981, Cochran et al. first described a maculopapular drug reaction, which spared the sites of previous X irradiation for a tumor. Since then, nearly 40 cases have been reported, mostly describing patient with alopecia areata of the scalp with hair growth within plaques of psoriasis. One of the mechanisms suggested is a role played by cytokine cross-regulation in competition among distinct immune responses.

CONCLUSION

We report the first case of Renbök phenomenon involving EM spared by a drug reaction. This phenomenon provides an insight into inflammatory response competition within a single patient.