[A case of erythema multiforme induced by regorafenib therapy for metastatic colon cancer].

A 47-year-old woman underwent colectomy for advanced colon cancer and thereafter received regorafenib therapy as fourth-line chemotherapy. On treatment day 12, the patient developed erythema multiforme (EM) induced by the regorafenib therapy. Immediately after regorafenib was withdrawn, the patient was treated with oral bepotastine and steroid ointment, which relieved the EM without progressing to Stevens-Johnson syndrome (SJS). Regorafenib is used for third- or fourth-line chemotherapy. Progression of regorafenib-induced EM to SJS may cause critical dysfunction among patients. Before administering regorafenib therapy, the patient should be made aware of this potential adverse effect and be advised to withdraw the treatment and visit the hospital immediately if symptoms of EM are observed.