Abstract: | Mucin‐producing cholangiocarcinoma, which excretes excessive amounts of mucin into the biliary tract and causes obstructive jaundice and cholangitis due to the mucin retention, is rare. In this paper, we report two cases of this disease, which were demonstrated by peroral cholangioscopy (POCS). The radiologic features of these tumors show the diffuse dilatation of the bile ducts demonstrated by computed tomography (CT) and ultrasonography (US), the amorphous filling defects in the dilated bile ducts revealed by cholangiography. Their endoscopic features are mucin flowing out from the papilla of Vater during endoscopic retrograde cholangiography (ERC), and the papillary tumor with contiguous superficial spread in the bile ducts observed by cholangioscopy, although removal of mucin in the biliary tract is sometimes necessary before cholangioscopy in order to examine the lesion sufficiently. According to the previous reports, prognosis after curative resection of these tumors is better than that of ordinary type of cholangiocarcinoma. Therefore, it is important to examine the tumor extension in the bile ducts by cholangioscopy, although a selection of route inserting cholangioscope is controversial. |