[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 Immediately after regorafenib was withdrawn, the patient was treated with oral bepotastine and steroid ointment, which relieved the EM without progressing to Stevens-Johnson syndrome (SJS).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.

[Pathological complete response in a large gastric GIST that became resectable after neoadjuvant chemotherapy with imatinib mesylate].

We report a case of a large gastric gastrointestinal stromal tumor (GIST), which became resectable and achieved pathological complete response after neoadjuvant chemotherapy with imatinib mesylate. A 59-year-old man presented with left hypochondrial pain. Abdominal computed tomography (CT) revealed gastric GIST invading the spleen and the diaphragm. Administration of imatinib mesylate was initiated as neoadjuvant chemotherapy. Six months after neoadjuvant chemotherapy with imatinib mesylate, abdominal CT revealed a reduction in tumor size. We judged the tumor resectable and performed partial gastrectomy and splenectomy. Histologically, number of myofibroblasts increased, but no viable tumor cells were observed. Pathological complete response was obtained.