Differential diagnosis of intrahepatic bile duct dilatation without demonstrable mass on ultrasonography or CT:: Benign versus malignancy

Background: The purpose of the present study was to define the differential diagnostic markers of benign and malignant bile duct strictures without demonstrable mass on ultrasonography (US) or computed tomography (CT) using aspects of clinical, laboratory and imaging findings. Methods: Between February 1995 and February 2001, 24 patients who underwent surgical resection for dilations of the bile duct (peripheral and hilar) without visible mass lesion on US or CT were included in our study. Hospital records, laboratory results, findings of imaging studies and pathological findings were reviewed retrospectively. Results: For laboratory results, levels of alkaline phosphatase (benign 163.9 +/- 145.1 vs malignant 407.25 +/- 481.7; p < 0.05) and CA 19-9 (benign 25.0 +/- 41.1 vs malignant 614.6 +/- 818.5; p < 0.05) levels were significantly elevated in the malignant group compared with that of the benign group. Findings such as thickening of the bile duct wall 5 mm (P < 0.05) on radiological examination, significant regional lymph node enlargement (>1 cm, p = 0.01) on CT scan and abrupt cut-off (P < 0.01), and separation of bile ducts (P < 0.05) on cholangiogram were differential diagnostic markers between the two groups. Conclusions: Preoperative laboratory data such as alkaline phosphatase and CA 19-9, and imaging findings such as significant wall thickening and regional lymph node enlargement on CT, abrupt cut-off and separation of bile duct on cholangiogram are useful differential diagnostic markers for benign and malignant bile duct strictures without demonstrable mass on US or CT. (C) 2003 Blackwell Publishing Asia Pty Ltd.