The clinicopathologic features of the intraductal growth (IG) type of peripheral cholangiocarcinoma (PCC) were examined retrospectively. Out of 112 patients who underwent surgery for PCC at Seoul National University Hospital, Seoul, Korea, between January 1980 and December 1997, 16 were classified as having the IG type. Thirteen were men and 3 were women. Their ages ranged from 38 to 73 years with a mean age of 55.9 years. Abdominal pain was the most common symptom and jaundice was found in 18.8%. Five patients had associated clonorchiasis and 6 patients experienced hepatolithiasis. Tumor sizes ranged from 0.5 cm to 14.0 cm with a mean of 4.3 cm. The tumor was located in the right lobe in 7 cases and the left lobe in 9 cases. Thirteen patients underwent major hepatic resection, and 3 underwent minor resection, involving a subsegmentectomy. Mucin was found in the bile in 4 cases. Pathology showed papillary adenocarcinoma with a background of adenomatous hyperplasia, and the absence of lymph node metastasis in all cases. The tumors were confined to the mucosa in 5 cases. Out of the 16 hepatic resections, 1 was palliative due to a positive margin. In 2 of the patients who underwent minor resections, recurrences developed, and 1 of these died 56 months after resection. Out of the 16 patients, 15 remain alive, ranging from 1 to 13 years, postoperatively. In conclusion, the IG type of PCC should be distinguished from other types of PCC because a favorable prognosis can be expected after complete surgical resection. (HEPATOLOGY 2000;31:12-17.)Intrahepatic or peripheral cholangiocarcinoma (PCC), a primary adenocarcinoma of the liver originating from the intrahepatic bile ducts (IHD), is the second most common primary hepatic malignancy, next to hepatocellular carcinoma. 1 Because the lesion is advanced by the time of diagnosis, 2 the possibility of surgical resection is limited and the prognosis is generally poor. [3][4][5][6][7][8][9] In 1992, Yamamoto et al. 10 classified PCC into 2 types, mass-forming (MF) and periductal-infiltrating (PI), and showed their different clinical behaviors. The MF type creates an apparent lesion in the liver, with frequent remnant hepatic recurrence after resection. The PI type causes a stricture or an obstruction of the IHD without forming a definite mass in the liver. It spreads along the Glisson' s capsule and metastasizes to the hilar lymph nodes. Later, another type, intraductal growth (IG), was added. 11 This type of tumor shows a papillary growth into the lumen of the bile duct. 12 There have been a few scattered reports about the clinical and pathological features of the IG type of PCC. 13,14 Here, we describe the clinical and pathological features of the IG type of PCC in 16 patients who underwent surgical resection at