5-Fluorouracil-induced erythema multiforme

Erythema multiforme is an immunologically mediated skin reaction to a forei gn antigen and can occur with many drugs. We report the first two cases of erythema multiforme induced by 5-fluorouracil (5-FU). The first case was in a man with inoperable gastric carcinoma being treated by continual infusio n who developed the classic rash involving the neck and upper chest, along with mouth ulceration and plantar-palmar erythrodysaesthesia. Histological confirmation was made by skin biopsy and the lesions resolved spontaneously . They recurred on restarting 5-FU. The second case was in a woman being gi ven adjuvant bolus 5-FU and folinic acid for Duke's C colon cancer who deve loped the rash during the first cycle. Again, the lesions settled spontaneo usly but recurred more severely on the second cycle. When treatment was cha nged to the specific thymidylate synthase inhibitor, raltitrexed, the cours e was completed uneventfully.