Background and Aim: Cholangiocarcinoma (CCA) is an aggressive biliary malignancy with poor prognosis, largely due to delayed diagnosis. In endemic regions, abdominal ultrasonography is a rapid, inexpensive, and widely available surveillance tool that may support earlier detection. However, some lesions are missed at initial screening and detected only on follow-up. This study aimed to characterize the sonographic features and anatomical distribution of previously undetected or newly identified CCAs detected through an ultrasound-based surveillance program. Methods: We retrospectively reviewed patients diagnosed with CCA through an abdominal ultrasound surveillance program in Nan Province, Thailand, between 2011 and 2017. Ultrasound findings and lesion locations were analyzed. All patients underwent confirmatory computed tomography or magnetic resonance imaging at Chulabhorn Hospital, with pathological confirmation of CCA. Descriptive and comparative analyses were performed. Results: Thirty-nine patients with 41 lesions were identified after a negative ultrasound examination 6 months earlier. Sonographic patterns included isolated hepatic masses, hepatic masses with bile duct dilatation, focal segmental bile duct dilatation, diffuse bile duct dilatation, and intraductal nodules. The most common presentations were isolated liver masses, liver masses with bile duct dilatation, and focal peripheral bile duct dilatation. Lesions were predominantly located in the peripheral intrahepatic bile ducts, especially second-order branches in hepatic segments VI and VII. Conclusions: Previously undetected or newly identified CCAs during ultrasound surveillance most commonly appear as small hepatic nodules or focal bile duct abnormalities arising from peripheral and second-order intrahepatic bile ducts, particularly in posterior right hepatic segments VI-VII. These patterns may reflect both liver fluke-associated cholangiocarcinogenesis and technical limitations of ultrasonography in hepatic blind areas. Careful evaluation of these high-risk regions and awareness of subtle signs, including small hyperechoic nodules and focal ductal dilatation, may improve early detection and optimize surveillance in endemic populations.
Promrach, N. , Nuangchamnong, N. , Chonyuen, S. , Seetasarn, J. , Hiranrat, P. , Waongenngarm, P. and Siripongsakun, S. (2026). Characteristics of Previously Undetected or Newly Emerging Cholangiocarcinoma Detected by Ultrasound Surveillance in an Endemic Area. Asian Pacific Journal of Cancer Prevention, 27(8), 3037-3044. doi: 10.31557/APJCP.2026.27.8.3037
MLA
Promrach, N. , , Nuangchamnong, N. , , Chonyuen, S. , , Seetasarn, J. , , Hiranrat, P. , , Waongenngarm, P. , and Siripongsakun, S. . "Characteristics of Previously Undetected or Newly Emerging Cholangiocarcinoma Detected by Ultrasound Surveillance in an Endemic Area", Asian Pacific Journal of Cancer Prevention, 27, 8, 2026, 3037-3044. doi: 10.31557/APJCP.2026.27.8.3037
HARVARD
Promrach, N., Nuangchamnong, N., Chonyuen, S., Seetasarn, J., Hiranrat, P., Waongenngarm, P., Siripongsakun, S. (2026). 'Characteristics of Previously Undetected or Newly Emerging Cholangiocarcinoma Detected by Ultrasound Surveillance in an Endemic Area', Asian Pacific Journal of Cancer Prevention, 27(8), pp. 3037-3044. doi: 10.31557/APJCP.2026.27.8.3037
CHICAGO
N. Promrach , N. Nuangchamnong , S. Chonyuen , J. Seetasarn , P. Hiranrat , P. Waongenngarm and S. Siripongsakun, "Characteristics of Previously Undetected or Newly Emerging Cholangiocarcinoma Detected by Ultrasound Surveillance in an Endemic Area," Asian Pacific Journal of Cancer Prevention, 27 8 (2026): 3037-3044, doi: 10.31557/APJCP.2026.27.8.3037
VANCOUVER
Promrach, N., Nuangchamnong, N., Chonyuen, S., Seetasarn, J., Hiranrat, P., Waongenngarm, P., Siripongsakun, S. Characteristics of Previously Undetected or Newly Emerging Cholangiocarcinoma Detected by Ultrasound Surveillance in an Endemic Area. Asian Pacific Journal of Cancer Prevention, 2026; 27(8): 3037-3044. doi: 10.31557/APJCP.2026.27.8.3037
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