[A Case of Local Resection for Rectal GIST Following Neoadjuvant Imatinib Mesylate Treatment].

A 67-year-old woman presented with bloody stools and constipation. A rectal digital examination revealed a smooth and elastic hard tumor in the posterior wall of the rectum. We diagnosed the tumor as rectal GIST measuring 5 cm in diameter. Because the patient desired anal preservation, neoadjuvant imatinib mesylate(IM)(400mg/day)treatment was administered. Although the diameter of the tumor reduced to 2 cm in the third week of administration, the patient experienced erythema-type drug eruption(Grade 3). We discontinued the IM treatment and initiated steroid therapy. After the eruption had disappeared, IM treatment was resumed, initially with half doses. Local transanal resection was performed 36days after the neoadjuvant IM treatment. Currently, the indication and the administration period of IM for preoperative treatment is not clear. It may be necessary to accumulate cases to evaluate neoadjuvant IM therapy.