AIM:To study the diagnosis of hepatocellular carcinoma(HCC)presenting as bile duct tumor thrombus with no detectable intrahepatic mass.METHODS:Six patients with pathologically proven bile duct HCC thrombi but no intrahepatic mass demonstrated on the preoperative imaging or palpated intrahepatic mass during operative exploration,were collected.Their clinical and imaging data were retrospectively analyzed.The major findings or signs on comprehensive imaging were correlated with the surgical and pathologic findings.RESULTS:Jaundice was the major clinical symptom of the patients.The elevated serum total bilirubin,direct bilirubin and alanine aminotransferase levels were in concordance with obstructive jaundice and the underlying liver disease.Of the 6 patients showing evidence of viral hepatitis,5 were positive for serum alpha fetoprotein and carbohydrate antigen 19-9,and 1 was positive for serum carcinoembryonic antigen.No patient was correctly diagnosed by ultrasound.The main features of patients on comprehensive imaging were filling defects with cup-shaped ends of the bile duct,with large filling defects presenting as casting moulds in the expanded bile duct,hypervascular intraluminal nodules,debris or blood clots in the bile duct.No obvious circular thickening of the bile duct walls was observed.CONCLUSION:Even with no detectable intrahepatic tumor,bile duct HCC thrombus should be considered in patients predisposed to HCC,and some imaging signs are indicative of its diagnosis. AIM: To study the diagnosis of hepatocellular carcinoma (HCC) presenting as bile duct tumor thrombus with no detectable intrahepatic mass. METHODS: Six patients with pathologically proven bile duct HCC thrombi but no intrahepatic mass demonstrated on the preoperative imaging or palpated intrahepatic mass during operative exploration, were collected. their clinical and imaging data were retrospectively analyzed. major findings or signs on comprehensive imaging were correlated with the surgical and pathologic findings. RESULTS: Jaundice was the major clinical symptom of the patients. elevated serum total bilirubin, direct bilirubin and alanine aminotransferase levels were in concordance with obstructive jaundice and the underlying liver disease. Of the 6 patients showing evidence of viral hepatitis, 5 were positive for serum alpha fetoprotein and carbohydrate antigen 19-9, and 1 was positive for serum carcinoembryonic antigen. No patient was correctly diagnosed by ultrasound. Main features of patients on comprehensive imaging were filling defects with cup-shaped ends of the bile duct, with large filling defects presenting as casting molds in the expanded bile duct, hypervascular intraluminal nodules, debris or blood clots in the bile duct. No obvious circular thickening of the bile duct walls was observed. CONCLUSION: Even with no detectable intrahepatic tumor, bile duct HCC thrombus should be considered in patients predisposed to HCC, and some imaging signs are indicative of its diagnosis.