[A Resected Case of Hilar Cholangiocarcinoma Confirmed as Pathological Complete Response Following Neoadjuvant S-1 Monotherapy].

A 74-year-old man was admitted to a local hospital with liver dysfunction. Imaging modalities revealed bile duct stenosis at the bifurcation of the anterior and posterior trunk. Exfoliative cytology of the bile and brushing cytology of the bile duct both revealed Class Ⅴ, and biopsy from the stenotic bile duct showed well differentiated adenocarcinoma. We diagnosed the patient with hilar cholangiocarcinoma and performed extended right bisectionectomy and biliary reconstruction after percuta- neous transhepatic right portal vein embolization(PTPE). Preoperatively, he was administered S-1(80mg/body weight/day) orally for 19 days. Histopathological assessment of the resected specimen revealed hemosiderin-laden macrophages without viable cancer cells, confirmingpatholog ical complete response(pCR).